Research Interests: Geology and Paleontology
Constraining the timing and style of subduction initiation in the Aleutian system is critical to model the Cenozoic geodynamic evolution of the Pacific. Until now, the oldest ages for the Aleutian arc suggest a subduction inception at... more
Constraining the timing and style of subduction initiation in the Aleutian system is critical to model the Cenozoic geodynamic evolution of the Pacific. Until now, the oldest ages for the Aleutian arc suggest a subduction inception at c.a. 46-47 Ma. However, the compositions of these samples (arc tholeiites and calc-alkaline rocks) are different from those of typical early-arc sequences found at extensively studied subduction systems (Izu-Bonin-Mariana), dominated by FABs and boninites. Thus, if the FAB/boninite model applies to the Aleutian, the oldest units might not have been recovered yet and the arc inception could have occurred earlier than 47 Ma. To test this hypothesis, we have sampled the lowermost submarine Aleutian sequences at ten forearc and rear-arc localities during the R/V SONNE Cruise 249. We present preliminary whole-rock major and trace element concentrations, Sr-Nd-Hf-Pb isotopes as well as U-Pb zircon dating on the recovered igneous rocks.
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New trace-element, radiogenic Sr-Nd-Pb isotopic and geochronological data from Middle-Late Cretaceous Zagros ophiolites of Iran give new insights into the tectono-magmatic history of these supra-subduction zone (SSZ)-type ophiolites. The... more
New trace-element, radiogenic Sr-Nd-Pb isotopic and geochronological data from Middle-Late Cretaceous Zagros ophiolites of Iran give new insights into the tectono-magmatic history of these supra-subduction zone (SSZ)-type ophiolites. The distribution of Middle-Late Cretaceous SSZ-type ophiolites in Iran comprises two parallel belts: (1) the outer Zagros ophiolitic belt and (2) the inner Zagros ophiolitic belt. These Middle-Late Cretaceous ophiolites were generated by seafloor spreading in what became the fore-arc and back-arc during the subduction initiation event and now define a ~3000-km-long belt from Cyprus to Turkey, Syria, Iran, the UAE, and Oman. The Zagros ophiolites contain complete (if disrupted) mantle and crustal sequences. Mantle sequences from both outer-belt and inner-belt ophiolites are dominated by dunites, harzburgites, and lherzolites with minor chromitite lenses. Peridotites are also intruded by gabbros and a variety of mafic to minor felsic (plagiogranite and da...
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ABSTRACT The Galapagos islands are built on young ocean crust close to the Galapagos Spreading Center (GSC), with coeval volcanism dispersed across more than 500 km of the archipelago. This dispersion has been interpreted to result from... more
ABSTRACT The Galapagos islands are built on young ocean crust close to the Galapagos Spreading Center (GSC), with coeval volcanism dispersed across more than 500 km of the archipelago. This dispersion has been interpreted to result from shearing of a mantle plume by rapid motion of the Nazca plate. Spatial variation in the composition of Galapagos and GSC lavas therefore provides basic information on plume structure, mantle flow patterns from the plume to the ridge, and the extent to which the plume influences melting and segmentation along the GSC. Lavas from the western and southern limbs of the Galapagos archipelago have very high 3He/4He, up to 30 RA (RA is the isotopic ratio in air, used as a reference), indicating the presence of a relatively undegassed plume source similar to that beneath Hawaii and Iceland. Other areas of the archipelago, such as the Wolf-Darwin lineament and the northern Galapagos islands, have relatively low 3He/4He, between ~6 and 8 RA. These areas also have systematically different Sr, Nd, Pb and Hf isotope characteristics. More than 75 basalts, collected at moderately high resolution along the GSC (10-20 km spacing), have been analyzed for helium isotope composition. Along the GSC 3He/4He ranges from 5.9 to 8.5 RA. High 3He/4He ratios resembling those of the western and southern Galapagos islands are not observed anywhere along the ridge axis. The most striking feature of the 3He/4He variations along the GSC is a large gradient from 89° to 93°W, where 3He/4He decreases westward from 8.4 to 6.8 RA. The GSC between 89° and 93°W has the shallowest axial depth and "axial high" morphology; both to its east and west the ridge is deeper and has "axial rift" morphology due to a decreased magma budget resulting from reduced thermal and material input from the nearby hotspot. Superposed on the helium isotope gradient from 89° to 93°W are small excursions in 3He/4He, near intersections of the GSC with the volcanic lineaments that radiate northward from the archipelago, possibly due to the presence of relatively narrow flow channels. The along-axis 3He/4He gradient also shows no significant inflection across the large transform fault at 90.7°W, suggesting that any component of mantle flow along the ridge axis, if it exists, is sufficiently deep that it is not influenced by the presence of the transform fault. Collectively, the helium isotope results suggest that (1) extraction of helium during partial melting beneath the archipelago may have caused helium to be a relatively ineffective downstream tracer of plume material at the GSC, and/or (2) mantle transported from beneath the islands toward the GSC is primarily derived from outer (northern) portions of the heterogeneous mantle plume where low 3He/4He ratios are prevalent.
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Preliminary U-series (230Th-238U, 231Pa-235U, 226Ra-230Th) disequilibria data are presented for young MORB glasses dredged at the Galapagos Spreading Center (GSC) between 85.20o W and 92.19o W. The GSC is situated north of the Galapagos... more
Preliminary U-series (230Th-238U, 231Pa-235U, 226Ra-230Th) disequilibria data are presented for young MORB glasses dredged at the Galapagos Spreading Center (GSC) between 85.20o W and 92.19o W. The GSC is situated north of the Galapagos hotspot and the application of U-series isotopes in this region allows us to address fundamental questions about melting dynamics and melt transport related to plume-ridge interaction.
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Research Interests: Geology and Peridotite
A major objective of the MEGAPRINT expedition of R/V Sonne was to locate and sample seamounts between the Galapagos Platform and the nearby Galapagos Spreading Center (GSC) in order to document bathymetric and geochemical effects of... more
A major objective of the MEGAPRINT expedition of R/V Sonne was to locate and sample seamounts between the Galapagos Platform and the nearby Galapagos Spreading Center (GSC) in order to document bathymetric and geochemical effects of plume-ridge interaction. Numerous previously undocumented seamounts were located and sampled. Their distribution and morphology varies systematically around the northern and eastern edges of the platform. Four distinct provinces are recognized: The Wolf-Darwin Triangle is bounded by the Wolf-Darwin lineament in the west, the GSC in the north and the 91oW transform in the east. It is characterized by large individual volcanic cones, many of which have summit craters, which appear to be aligned along three NW trending lineaments (including the Wolf-Darwin lineament). These trends are sub-parallel, perhaps suggesting that they have formed at slightly different times in an evolving stress regime. Several of the larger seamounts have prominent terraces at app...
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Research Interests: Geology and Geochemistry
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Widespread hardrock sampling of the Manihiki Plateau has been carried out in 2007 during the SO193 cruise with the German Research Vessel" Sonne" and thus far achieved the densest igneous sample coverage amongst insitu oceanic... more
Widespread hardrock sampling of the Manihiki Plateau has been carried out in 2007 during the SO193 cruise with the German Research Vessel" Sonne" and thus far achieved the densest igneous sample coverage amongst insitu oceanic LIP's. Here we ...
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Variations in age and composition of the subduction input, slab dip, crustal thickness and crustal composition are likely to be the major controls on spatial and temporal variations along the Central American Volcanic Arc (CAVA). Our... more
Variations in age and composition of the subduction input, slab dip, crustal thickness and crustal composition are likely to be the major controls on spatial and temporal variations along the Central American Volcanic Arc (CAVA). Our extensive new ...
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Abstract The Hikurangi and Manihiki Plateaus, extensively sampled on the SONNE 168 and 193 cruises, have a similar temporal and geochemical evolution. The two plateaus began with a main tholeiitic plateau stage (c. 126-116 Ma) followed by... more
Abstract The Hikurangi and Manihiki Plateaus, extensively sampled on the SONNE 168 and 193 cruises, have a similar temporal and geochemical evolution. The two plateaus began with a main tholeiitic plateau stage (c. 126-116 Ma) followed by a later (seamount-forming) ...
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Prior attempts to understand nitrogen geochemistry of volcanic arcs have generally been limited to study of active fumaroles. Here we analyze whole-rock N concentration and delta 15N for active (Central American) and older (Alboran)... more
Prior attempts to understand nitrogen geochemistry of volcanic arcs have generally been limited to study of active fumaroles. Here we analyze whole-rock N concentration and delta 15N for active (Central American) and older (Alboran) volcanic systems using sealed-tube combustion methods. Whole-rock N-isotope studies can sample N present in quenched glass, fluid inclusions, plagioclase, or potassic minerals from a range of volcanic systems. Six basaltic samples from the volcanic front of Nicaragua have delta 15Nair from-3.3 to+ ...
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Hoernle, Kaj, Hauff, Folkmar, Werner, Reinhard, van den Bogaard, Paul, Timm, C., Michael, P., Coffin, M., Mortimer, N. and Davy, B. (2009) The Largest Preserved Magmatic Event (LIP) on our Planet: More Pieces to the Puzzle [Invited talk]... more
Hoernle, Kaj, Hauff, Folkmar, Werner, Reinhard, van den Bogaard, Paul, Timm, C., Michael, P., Coffin, M., Mortimer, N. and Davy, B. (2009) The Largest Preserved Magmatic Event (LIP) on our Planet: More Pieces to the Puzzle [Invited talk] In: Earth and Ocean Sciences Seminar Series, University of South Carolina, 10.09.2009, Columbia, USA. ... Full text not available from this repository.
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Hoernle, Kaj, Hauff, Folkmar, Werner, Reinhard, van den Bogaard, Paul, Timm, Christian, Michael, P., Coffin, M., Mortimer, N. and Davy, B. (2010) A common multi-stage evolution for the Manihiki, Hikurangi and Ontong Java Plateaus: Is... more
Hoernle, Kaj, Hauff, Folkmar, Werner, Reinhard, van den Bogaard, Paul, Timm, Christian, Michael, P., Coffin, M., Mortimer, N. and Davy, B. (2010) A common multi-stage evolution for the Manihiki, Hikurangi and Ontong Java Plateaus: Is there a link between the Greater Ontong Java Event and the South Pacific Superswell? [Invited talk] In: Geodynamics Seminar, Lamont Doherty Earth Observatory, 10.05. 2010, Palisades, NY, USA.
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Research Interests: Earth Sciences, Geology, Geochemistry, Physical sciences, Mantle plumes, and 13 morePb isotopes, Rare Earth Element Mineralization, First record, Hot Spot, Rare Earth, Large Igneous Province, Mantle Sources, Mantle plume, Low Temperature, Volcanic Rock, Trace element, Caribbean Plate Tectonic Evolution, and Hf isotopes
Leibniz Institute of Marine Sciences, IFM-GEOMAR, Wischhofstr. 1-3, 24114 Kiel, Germany; email: mportnyagin@ifm-geomar.de V.I.Vernadsky Institute of Geochemistry and Analytical Chemistry RAN, Kosygin St. 19, 119991 Moscow, Russia... more
Leibniz Institute of Marine Sciences, IFM-GEOMAR, Wischhofstr. 1-3, 24114 Kiel, Germany; email: mportnyagin@ifm-geomar.de V.I.Vernadsky Institute of Geochemistry and Analytical Chemistry RAN, Kosygin St. 19, 119991 Moscow, Russia Department of Earth & Ocean Sciences, University of South Carolina, 701 Sumter St., EWSC617, Columbia SC 29208, USA P.P.Shirshov Institute of Oceanology, Nakhimovski Prospekt 36, 117997 Moscow, Russia 5 Institute of volcanology and seismology, Piip 9, 683006 Petropavlovsk-Kamchatsky, Russia
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The accretion mechanisms forming oceanic crust at fast spreading ridges are still under controversial discussion. Thermal, petrological, and geochemical observations predict different end-member models, i.e., the gabbro glacier and the... more
The accretion mechanisms forming oceanic crust at fast spreading ridges are still under controversial discussion. Thermal, petrological, and geochemical observations predict different end-member models, i.e., the gabbro glacier and the sheeted sill model. They all bear implications for heat transport, temperature distribution, mode of crystallization and hydrothermal heat removal over crustal depth. In a typical MOR setting, temperature is the key factor driving partitioning of incompatible elements during crystallization.
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Splitting of the Vitiaz arc formed the Tonga-Kermadec and Lau-Colville Ridges (southwestern Pacific Ocean), separated by the Lau Basin in the north and Havre Trough in the south. We present new trace element and Sr-Nd-Hf-Pb isotope... more
Splitting of the Vitiaz arc formed the Tonga-Kermadec and Lau-Colville Ridges (southwestern Pacific Ocean), separated by the Lau Basin in the north and Havre Trough in the south. We present new trace element and Sr-Nd-Hf-Pb isotope geochemistry for the Kermadec and Colville Ridges extending ∼900 km north of New Zealand (36°S–28°S) in order to (1) compare the composition of the arc remnants with Quaternary Kermadec arc volcanism, (2) constrain spatial geochemical variations in the arc remnants, (3) evaluate the effect of Hikurangi igneous plateau subduction on the geochemistry of the older arc lavas, and (4) elucidate what may have caused arc splitting. Compared to the Kermadec Ridge, the Colville Ridge has higher more-incompatible to less-incompatible immobile element ratios and largely overlapping isotope ratios, consistent with an origin through lower degrees of melting of more enriched upper mantle in the Vitiaz rear arc. Between ca. 8 and 3 Ma, both halves of the arc (∼36°S–29°S...
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Volcanic sequences on ocean islands record the temporal evolution of underlying magmatic systems and provide insights into how silicic crust is produced away from convergent margins. Assimilation has often been suspected to contribute,... more
Volcanic sequences on ocean islands record the temporal evolution of underlying magmatic systems and provide insights into how silicic crust is produced away from convergent margins. Assimilation has often been suspected to contribute, but the detection of such a process and its evolving maturity during migration across a mantle plume is less well documented. Here we present new major and trace element and Sr-Nd-Pb-U-Th-Ra-Pa isotope data that facilitate comparison of basanite to phonolite evolution on Tenerife (Canary Islands) with that shown by published data from La Palma. On both islands, (230Th/238U) ratios decrease with differentiation from parental magmas with 230Th excess toward different, silicic contaminants in secular equilibrium. On La Palma, this is inferred to reflect assimilation of small amounts of mafic wall rock. On Tenerife, both (230Th/238U) and (231Pa/235U) ratios decrease toward 1 with increasing differentiation, and this is accompanied by a subtle increase in Pb isotope ratios. At the same time, (226Ra/230Th) ratios change from 1 (a hitherto unreported magnitude). The Tenerife assimilant is thus constrained to be a partial melt of syenite formed in equilibrium with residual feldspar. The differences reflect a primarily deeper, more mafic magma system beneath La Palma during its late shield-building stage, whereas recent magmatic evolution at Tenerife occurs primarily at lower temperatures in small, shallower magma systems formed during its post–basaltic shield stage. Differentiation takes millennia or less.
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The ~120Ma Manihiki Plateau basement consists of high-Ti tholeiitic basalts with EM-I type isotopic signatures, similar to the Singgalo basalts at Ontong Java, and low-Ti tholeiitic basalts with FOZO (Kwaimbaita/Kroenke) to HIMU-type... more
The ~120Ma Manihiki Plateau basement consists of high-Ti tholeiitic basalts with EM-I type isotopic signatures, similar to the Singgalo basalts at Ontong Java, and low-Ti tholeiitic basalts with FOZO (Kwaimbaita/Kroenke) to HIMU-type isotopic compositions, similar to late stage volcanism on Hikurangi and Manihiki Plateaus (Hoernle et al. 2010; Timm et al. 2011). The low-Ti basalts have affinities to boninites and have been interpreted to be derived from residual mantle wedge mantle (Ingle et al. 2007). New major, volatile and trace element and radiogenic isotope data have been generated from fresh low-Ti glass samples recovered during R/V Sonne cruises SO193 and SO225. The low-Ti samples have distinctly lower Ti/V ratios compared to lavas from Ontong Java Plateau (Kwaimbaita-Kroenke and Singgalo), but similar to boninitic rocks. Glasses and melt inclusions in olivine have low volatile contents (0.12-0.25 wt% H2O). Olivine chemistry points to derivation from peridotite source. Therefore we interpret the low-Ti lavas to have formed through melting of dry and depleted peridotite at high temperatures, consistent with Timm et al (2011). The low-Ti group is characterized by U-shaped trace element patterns. The glass samples form linear mixing arrays on radiogenic isotope diagrams, pointing to the involvement of two components: 1) a component ultra-depleted in highly incompatible elements (UDC) but with intermediate Pb, Sr and Nd isotopic compositions, being similar to Kwaimbaita/Kroenke lavas from Ontong Java, and 2) an enriched component with HIMU-type incompatible element and isotopic characteristics, similar to late-stage volcanism on Manihiki, Hikurangi and Ontong Java (e.g. Hoernle et al. 2010). The ultra-depleted, FOZO-like mantle component could represent second stage melting of FOZO type mantle or re-melting of young recycled oceanic lithosphere within the plume head. Enrichment with HIMU type melts is required to explain the enrichment in the most incompatible elements and distinct U-shaped patterns of these melts. The presence of dry, boninite-like second stage melts in the Manihiki Plateau basement shows direct geochemical/petrological evidence for anomalously high temperatures in the upper mantle caused by a mantle plume.
The Canary Islands, built on the continental rise and slope (Figs. 1,2), are one of the major volcanic island chains in the oceans. There is hardly another group of volcanic islands in the world, neither the Azores nor the Hawaiian... more
The Canary Islands, built on the continental rise and slope (Figs. 1,2), are one of the major volcanic island chains in the oceans. There is hardly another group of volcanic islands in the world, neither the Azores nor the Hawaiian islands, with such long histories of eruptions (Fig. 3) — spanning 20 or more Ma2 on some individual islands — and such an enormous variety of volcanic and plutonic rocks. Moreover, the magnificent outcrops on the leeward sides of the islands, due to low rainfall, scant or absent vegetation, and deep canyons, make the islands especially appealing to the earth scientist.
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The Bowers and Shirshov Ridges (hereafter BR and SR, respectively) are two prominent submarine structures of unknown age and provenance in the Bering Sea. So far only a few geochemical data exist on the composition of basement rocks from... more
The Bowers and Shirshov Ridges (hereafter BR and SR, respectively) are two prominent submarine structures of unknown age and provenance in the Bering Sea. So far only a few geochemical data exist on the composition of basement rocks from the SR (Silantyev et al. ...
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The Hikurangi oceanic plateau or large igneous province (LIP), located east of the North Island of New Zealand, covers an area of 350,000 km3 and is located at a depth of 2,500-3,500 b.s.l. The Hikurangi plateau was possibly connected to... more
The Hikurangi oceanic plateau or large igneous province (LIP), located east of the North Island of New Zealand, covers an area of 350,000 km3 and is located at a depth of 2,500-3,500 b.s.l. The Hikurangi plateau was possibly connected to the Manihiki LIP (now located 3000 km to the north) but may have been separated by Cretaceous seafloor spreading at the Osbourn Trough (Billen and Stock, 2000, J. Geophys. Res., 106, 13481-13489). Therefore it may have formed part of the "greater Ontong Java Plateau event" (Coffin and Eldholm, Geology, 21, 515-51), the largest magmatic event preserved on Earth. During the R/V Sonne SO168 ZEALANDIA cruise, 77 dredge hauls containing igneous samples were recovered from the Hikurangi Plateau. Volcanic rocks were obtained from 1) the plateau basement along the 1 km high Rapuhia Scarp, 2) large guyot-type seamounts within the plateau, and 3) ridge-type seamounts associated with rifting of the NE plateau margin (Hoernle et al., 2004, EOS). The r...
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U-Th-Ra disequilibria of basanites, tephrites, and phonolites from the A.D. 1585 eruption on La Palma, Canary Islands, constrain magma differentiation times in an ocean-island rift zone. The insignificant difference in (230Th)/(232Th)... more
U-Th-Ra disequilibria of basanites, tephrites, and phonolites from the A.D. 1585 eruption on La Palma, Canary Islands, constrain magma differentiation times in an ocean-island rift zone. The insignificant difference in (230Th)/(232Th) implies differentiation from basanite to phonolite in <15 k.y. 226Ra has a half-life of 1600 yr, however, and permits higher temporal resolution; (226Ra)/(230Th) disequilibria are highest in the phonolites
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Here we present the first radiometric age data and a comprehensive geochemical data set (including major and trace element and SrNdPbHf isotope ratios) for samples from the Hikurangi Plateau basement and seamounts on and adjacent to... more
Here we present the first radiometric age data and a comprehensive geochemical data set (including major and trace element and SrNdPbHf isotope ratios) for samples from the Hikurangi Plateau basement and seamounts on and adjacent to the plateau obtained ...
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ABSTRACT a b s t r a c t Silicic Icelandic magmas are widely believed to contain low to moderate H 2 O content prior to degassing, and that their high explosivity mostly results from the interaction of the magmas with ice or meteoric... more
ABSTRACT a b s t r a c t Silicic Icelandic magmas are widely believed to contain low to moderate H 2 O content prior to degassing, and that their high explosivity mostly results from the interaction of the magmas with ice or meteoric water. Here we report the compositions of glass inclusions (SiO 2 ¼ 57–72 wt%, K 2 O ¼ 1.3– 2.6 wt%) in Fe-rich olivines (Fo 2–42) from the largest Holocene eruptions of Hekla volcano (H3 and H4) on Iceland, which preserved quenched melts with very high primary H 2 O contents (3.3–6.2 wt%). The silicic Hekla melts originate primarily by extensive ($ 90%) crystal fractionation of H 2 O-poor ($ 0.6 wt%) basalts and represent an end member in the systematics of terrestrial magmas because they originate at low fO 2 (DQFM $ À0.1 to À 0.4) and have as high H 2 O contents as significantly more oxidized island-arc magmas (DQFM Z1). This demonstrates that H 2 O and DQFM do not correlate in silicic magmas from different tectonic settings, and that fO 2 , not H 2 O content, shows a major difference between silicic ocean-island (e.g., Icelandic) and island-arc magmas. Analysis of available experimental data suggests that high H 2 O activity and low fO 2 expand the field of olivine stability in silicic melts. Low fO 2 and low MgO content could also suppress crystallization of amphibole. On the basis of these results we propose that an anhydrous mineral assemblage bearing Fe-rich olivine in evolved volcanic and Skaergaard-type intrusive rocks does not imply low H 2 O in magmas prior to degassing but, in contrast to the commonly held view, is an indicator of H 2 O-rich silicic parental magmas crystallized at low fO 2 . Finally, the high H 2 O content in magma was a major driving force of the largest explosive eruptions of Hekla volcano and must be at least as important for driving silicic explosive volcanism on Iceland as magma–ice interaction. & 2012 Elsevier B.V. All rights reserved.
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Here we present the first radiometric age data and a comprehensive geochemical data set (including major and trace element and SrNdPbHf isotope ratios) for samples from the Hikurangi Plateau basement and seamounts on and adjacent to... more
Here we present the first radiometric age data and a comprehensive geochemical data set (including major and trace element and SrNdPbHf isotope ratios) for samples from the Hikurangi Plateau basement and seamounts on and adjacent to the plateau obtained ...
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Volcanic pebbles in gravels from Sites 977 and 978 in the Alboran Sea (western Mediterranean) were dated (using the 40Ar/39Ar single-crystal laser technique) and analyzed for their major-and trace-element compositions (determined by X-ray... more
Volcanic pebbles in gravels from Sites 977 and 978 in the Alboran Sea (western Mediterranean) were dated (using the 40Ar/39Ar single-crystal laser technique) and analyzed for their major-and trace-element compositions (determined by X-ray ...
... These segments of the subduction zone provide starkly contrasting situations with differing oceanic crustal input (East Pacific Rise vs. ... In Nicaragua H 2 O shows a general increase with decreasing Fo of the host olivine,... more
... These segments of the subduction zone provide starkly contrasting situations with differing oceanic crustal input (East Pacific Rise vs. ... In Nicaragua H 2 O shows a general increase with decreasing Fo of the host olivine, reflecting incompatible behavior during ... in samples from Fo ...
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We present geochronological and geochemical data for eight plutonic rocks from five locations in the Pine Island Bay area of West Antarctica, collected during RV Polarstern expedition ANT-XXIII/4. Ar-Ar laser method dating yielded closure... more
We present geochronological and geochemical data for eight plutonic rocks from five locations in the Pine Island Bay area of West Antarctica, collected during RV Polarstern expedition ANT-XXIII/4. Ar-Ar laser method dating yielded closure temperatures ages of c. 147–98 Ma for dioritic and granitic plutonic rocks and an age range of c. 97–95 Ma for granitoid and trachyandesitic dykes. Major and trace element compositions indicate that all rocks have an I-type subduction-related chemistry. There are no A-type granitic rocks in our dataset, and none are yet reported from the Pine Island Bay area. Our results confirm earlier models of post 100 Ma subduction on this part of the Gondwana margin.
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Most Central American magmas have a typical arc geochemical signature, however magmas in southern Central America (central Costa Rica and Panama) have isotopic and trace element compositions with an OIB affinity, similar to the... more
Most Central American magmas have a typical arc geochemical signature, however magmas in southern Central America (central Costa Rica and Panama) have isotopic and trace element compositions with an OIB affinity, similar to the Galapagos-OIB lavas (eg, Ba/La<40, ...
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U-Th-Ra disequilibria of basanites, tephrites, and phonolites from the A.D. 1585 eruption on La Palma, Canary Islands, constrain magma differentiation times in an ocean-island rift zone. The insignificant difference in (230Th)/(232Th)... more
U-Th-Ra disequilibria of basanites, tephrites, and phonolites from the A.D. 1585 eruption on La Palma, Canary Islands, constrain magma differentiation times in an ocean-island rift zone. The insignificant difference in (230Th)/(232Th) implies differentiation from basanite to phonolite in &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;15 k.y. 226Ra has a half-life of 1600 yr, however, and permits higher temporal resolution; (226Ra)/(230Th) disequilibria are highest in the phonolites
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Research Interests: Earth Sciences, Geochemistry, Petrology and Geochemistry, Large Igneous Provinces, Isotopes, and 15 morePhysical sciences, Lower mantle, Mantle plumes, Pb isotopes, Heat Flux, Trace Elements, Flood Basalts, Hot Spot, Large Igneous Province, Mantle Sources, Mantle plume, Trace element, Cumulant, Hot Spots, and Oceanic crust
Heydolph, Ken, Hoernle, Kaj, Hauff, Folkmar, van den Bogaard, Paul and Sadofsky, S.(2007) Potential source components for NW Central American Arc lavas [Talk] In: Latin America Colloquium, 11.-13.04, Kiel (Unpublished)
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Research Interests: Earth Sciences, Geochemistry, Petrology and Geochemistry, Large Igneous Provinces, Isotopes, and 15 morePhysical sciences, Lower mantle, Mantle plumes, Pb isotopes, Heat Flux, Trace Elements, Flood Basalts, Hot Spot, Large Igneous Province, Mantle Sources, Mantle plume, Trace element, Cumulant, Hot Spots, and Oceanic crust
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Large tectonic plates are known to be susceptible to internal deformation, leading to a~range of phenomena including intraplate volcanism. However, the space and time dependence of intraplate deformation and its relationship with changing... more
Large tectonic plates are known to be susceptible to internal deformation, leading to a~range of phenomena including intraplate volcanism. However, the space and time dependence of intraplate deformation and its relationship with changing plate boundary configurations, subducting slab geometries, and absolute plate motion is poorly understood. We utilise a buoyancy-driven Stokes flow solver, BEM-Earth, to investigate the contribution of subducting slabs through time on Pacific plate motion and plate-scale deformation, and how this is linked to intraplate volcanism. We produce a series of geodynamic models from 62 to 42 Ma in which the plates are driven by the attached subducting slabs and mantle drag/suction forces. We compare our modelled intraplate deformation history with those types of intraplate volcanism that lack a clear age progression. Our models suggest that changes in Cenozoic subduction zone topology caused intraplate deformation to trigger volcanism along several linear...
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The Manihiki Plateau represents a Cretaceous Large Igneous Province (LIP) in the SW-Pacific. In May/June 2007, R/V Sonne cruise SO193 conducted ~4,700 nm of bathymetric mapping in key areas of the Manihiki Plateau region, and the first... more
The Manihiki Plateau represents a Cretaceous Large Igneous Province (LIP) in the SW-Pacific. In May/June 2007, R/V Sonne cruise SO193 conducted ~4,700 nm of bathymetric mapping in key areas of the Manihiki Plateau region, and the first hard rock sampling of all major geomorphological units of the plateau as well as of seamounts on adjacent oceanic crust. The research project
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KALMAR is a Russian-German collaborative project that investigates the triple junction of the Kurile- Kamchatka and Aleutian Island Arc system. This system is seismically and volcanically the most active subduction zone on Earth with an... more
KALMAR is a Russian-German collaborative project that investigates the triple junction of the Kurile- Kamchatka and Aleutian Island Arc system. This system is seismically and volcanically the most active subduction zone on Earth with an ongoing eruption record in the Kamchatka volcanic front since the Pleistocene. The amount and explosivity of the eruptions point towards a significant influence of fluids in the subducted crust and upper mantle on the composition of the magmas and the volcanological evolution. The significant release of climate-relevant magmatic gases is related to the most active volcanoes associated with the Kamchatka-Aleutian-Triple Junction. In order to better understand the processes that control the subduction, KALMAR investigates the geodynamic-volcanic-magmatic and the oceanographic-climatic evolution of the Kurile-Kamchatka-Aleutean Arc system in five closely coupled subprojects. The subprojects address the processes involved in a wide range of geophysical, ...
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To better understand material cycling from subducting slabs to arc magmas we are studying primitive magmas and melt inclusions from Central America. Examining different parts of Central America shows the effects of variations in... more
To better understand material cycling from subducting slabs to arc magmas we are studying primitive magmas and melt inclusions from Central America. Examining different parts of Central America shows the effects of variations in subduction input, slab dip and resulting thermal regime on the geochemistry of arc magmas. Here we report new data from the volcanic front of Guatemala, which
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The morphology of the northern Wharton Basin (South-East Indian Ocean) is dominated by the Investigator Ridge, a ~1800 km long, N-S striking fracture zone and a huge (~1800 x 600 km) submarine volcanic province of unknown origin which... more
The morphology of the northern Wharton Basin (South-East Indian Ocean) is dominated by the Investigator Ridge, a ~1800 km long, N-S striking fracture zone and a huge (~1800 x 600 km) submarine volcanic province of unknown origin which includes Cocos/Keeling Islands, Muirfield Seamount, Vening Meinesz Seamounts, Christmas Island, and many unnamed seamounts further south and east. From August 3 through
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ABSTRACT The Woodlark Basin east of Papua New Guinea is one of the few places on Earth where a spreading axis propagates into continental crust. This special tectonic setting allows insights into compositional variations of the magma... more
ABSTRACT The Woodlark Basin east of Papua New Guinea is one of the few places on Earth where a spreading axis propagates into continental crust. This special tectonic setting allows insights into compositional variations of the magma sources as continental extension and break-up changes to the formation of new ocean crust. R/V Sonne cruise SO203 mapped and sampled the neovolcanic zone of the four westernmost (closest to continent) spreading segments, from the youngest Segment 1 in the west to the oldest sampled Segment 4 in the east. Major (EMPA) and trace element (LA-ICPMS) data of 208 glass samples, as well as Sr-Nd-Pb (double spike) isotopic compositions of 48 glasses are presented. Major and trace element compositions vary systematically between the four segments. Segment 1 glasses comprise tholeiites, basaltic andesites and rhyolites, while Segments 2 to 4 solely comprise tholeiites. Incompatible trace elements display a wide range in Segment 1 lavas, whereas the older Segments 2 to 4 have more distinct N-MORB like patterns. Nb/U and Nd/Pb are largely within the array of mantle melts, but in some Segment 1 lavas they are significantly lowered, indicating an influence by continental crust. Segment 1, -3 and -4 lavas possess relatively radiogenic 87Sr/86Sr, unradiogenic 143Nd/144Nd and Pb isotopic compositions that trend from the Pacific MORB field toward continental crust and enriched (EM1-2) mantle sources. Segment 2, however, is offset toward more radiogenic 206Pb/204Pb, which may reflect a higher time integrated 238U/204Pb (HIMU) ratio of its source. The geochemical zonation along the spreading centers of the Woodlark Basin likely reflects compositional variation of continental lithosphere and underlying asthenosphere and/or changes in their relative proportion during magma genesis. This can be attributed to a shift from continent break-up and incipient spreading in the west to more matured spreading in the east. The deepening of the magma sources with time is probably also associated with involvement of a larger volume of mantle region and increasing degrees of partial melting. The Segment 2 with HIMU flavour can in this case represent melts from small volume compositional heterogeneities in a common MORB source which are diluted with more typical high-degree melts from DMM mantle dominating the compositions of Segment 4. Somewhat increased involvement of EM1-continental crust material in Segment 3 may be related to a recent spreading axis jump, which might favour sampling of shallow continental blocks still preserved within the lithosphere under this segment. Altogether, the petrogenesis at Segment 1 is the most complicated, with involvement of crustal assimilation as well as subcontinental lithospheric mantle.
Understanding the pattern of solid mantle deformation in subduction zones is fundamentally important in constraining its effect on geodynamic processes such as material transport and thermal structure. Measurements of shear-wave... more
Understanding the pattern of solid mantle deformation in subduction zones is fundamentally important in constraining its effect on geodynamic processes such as material transport and thermal structure. Measurements of shear-wave splitting, and perhaps even travel-time anomalies, in both local and teleseismic (e.g., S,SKS,PKS) body waves allow us to characterize upper mantle seismic anisotropy. When combined with results from deformation experiments
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During the MEGAPRINT expedition (R/V Sonne Cruise SO158), we mapped and sampled the eastern Galapagos spreading center (GSC) between 85\deg and 92.5\deg W using the newly installed SIMRAD EM120 multibeam echosounder. The new maps reveal a... more
During the MEGAPRINT expedition (R/V Sonne Cruise SO158), we mapped and sampled the eastern Galapagos spreading center (GSC) between 85\deg and 92.5\deg W using the newly installed SIMRAD EM120 multibeam echosounder. The new maps reveal a wide range of axial morphologies, ranging through several axial valley types, some with pronounced graben structures, to both narrow and broad axial highs. The
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... A propagating fracture model for the Canary Islands, however, fails to explain the origin of the seamounts NE of the Canaries [13]. Based on geophysical data, Holick et al. [8] proposed a Canary hotspot track starting at ∼65 Ma near... more
... A propagating fracture model for the Canary Islands, however, fails to explain the origin of the seamounts NE of the Canaries [13]. Based on geophysical data, Holick et al. [8] proposed a Canary hotspot track starting at ∼65 Ma near Lars Seamount, which would fit well with the ...
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Intraplate volcanism is mainly attributed to upwelling and subsequent partial melting of hot mantle material. However, the origin of these hot mantle material is still a matter of an active debate (eg www. mantleplume. org). On the New... more
Intraplate volcanism is mainly attributed to upwelling and subsequent partial melting of hot mantle material. However, the origin of these hot mantle material is still a matter of an active debate (eg www. mantleplume. org). On the New Zealand micro continent Zealandia ( ...
... Wanke, Maren, Portnyagin, Maxim V., Werner, Reinhard, Hauff, Folkmar, Hoernle, Kaj and Garbe-Schönberg, Dieter (2011) New geochemical data provide evidence for an island-arc origin of the Bowers and Shirshov Ridges (Bering Sea, NW... more
... Wanke, Maren, Portnyagin, Maxim V., Werner, Reinhard, Hauff, Folkmar, Hoernle, Kaj and Garbe-Schönberg, Dieter (2011) New geochemical data provide evidence for an island-arc origin of the Bowers and Shirshov Ridges (Bering Sea, NW Pacific) [Talk] In: KALMAR ...
... The R/V SONNE cruise (funded by the German Ministry for Education and Research) had two major study areas. ... The profile was kept to 15 km, because further north the Cocos Ridge begins, which was extensively sampled during the R/V... more
... The R/V SONNE cruise (funded by the German Ministry for Education and Research) had two major study areas. ... The profile was kept to 15 km, because further north the Cocos Ridge begins, which was extensively sampled during the R/V Melville MV1007 cruise in June 2010. ...
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... and F minima in Nicaraguan samples. In evolved melt inclusions in pyroxene and feldspar, F shows a maxima in Nicaragua and Cl shows a systemic decrease fromCosta Rica to Guatemala. As suggested by previous studies ...
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Research Interests: Biochemistry, Bioinformatics, Environmental Science, Developmental Biology, Climate Change, and 15 moreComputational Biology, Biotechnology, Cancer, Biology, Cell Cycle, Ecology, Drug Discovery, Astrophysics, Anisotropy, Astronomy, DNA, Cell Signalling, Earth Science, Chemical Structure, and Anisotropia
... concentrated. The basalts dredged here represent the freshest rocks found so far on the Archipelago. They are remarkably vesicular with some samples resembling volcanic bombs indicative of gas-driven magma fragmentation. Such ...
Young (≤ 3Ma) lavas from volcanic centers along a 75-km NS transect from northern Madeira Island to a submarine volcanic field 55km south of Madeira exhibit distinct spatial geochemical variations. From south to north along this... more
Young (≤ 3Ma) lavas from volcanic centers along a 75-km NS transect from northern Madeira Island to a submarine volcanic field 55km south of Madeira exhibit distinct spatial geochemical variations. From south to north along this transect, there is a general ...
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ABSTRACT Asymmetrically zoned hotspot tracks in the Pacific Ocean are interpreted to have formed from zoned plumes originating from the large-scale, lower-mantle, low-seismic-velocity anomaly (superplume?) beneath the southern Pacific,... more
ABSTRACT Asymmetrically zoned hotspot tracks in the Pacific Ocean are interpreted to have formed from zoned plumes originating from the large-scale, lower-mantle, low-seismic-velocity anomaly (superplume?) beneath the southern Pacific, providing direct information about lower-mantle compositional heterogeneity. New trace-element and Sr-Nd-Hf-Pb isotope data from the classic Tristan-Gough hotspot track in the South Atlantic also display a bilateral, asymmetric zonation with two distinct mantle source components, making it the first zoned plume to be recognized overlying the African superplume. The plume zonation can be traced for 70 m.y., four times longer than recognized for Pacific zoned hotspot tracks. These findings confirm that the proposed zonation of Pacific hotspots is not simply a geochemical oddity, but could be a major feature of plumes derived from lower-mantle superplumes. We propose that the enriched southern Gough subtrack source with elevated Pb-207/Pb-204 and Pb-208/Pb-204 at a given Pb-206/Pb-204, but low Nd-143/Nd-144 and Hf-176/Hf-177 (DUPAL-like composition), may reflect the African superplume composition, whereas the more depleted northern Tristan subtrack source could represent a mixture of the superplume with the surrounding depleted mantle. Our results strengthen arguments that the enriched signature (DUPAL anomaly) in the South Atlantic could be derived from the lower mantle.
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Research Interests: Geology and Geochemistry
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We present new major and trace element and O–Sr–Nd-isotope data for igneous rocks from the western Mediterranean Alborán Sea, collected during the METEOR 51/1 cruise, and for high-grade schists and gneisses from the continental Alborán... more
We present new major and trace element and O–Sr–Nd-isotope data for igneous rocks from the western Mediterranean Alborán Sea, collected during the METEOR 51/1 cruise, and for high-grade schists and gneisses from the continental Alborán basement, drilled during the Ocean Drilling Programme (ODP Leg 161, Site 976). The geochemical data allow a detailed examination of crustal and mantle processes involved
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Quaternary volcanic rocks from the Central American Volcanic Arc in central Nicaragua and central Costa Rica exhibit major differences in their volatile, trace element and isotopic compositions. Olivine-hosted melt inclusions in... more
Quaternary volcanic rocks from the Central American Volcanic Arc in central Nicaragua and central Costa Rica exhibit major differences in their volatile, trace element and isotopic compositions. Olivine-hosted melt inclusions in Nicaraguan volcanic rocks ...
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Timm, Christian, Hoernle, Kaj, Werner, Reinhard, Hauff, Folkmar, van den Bogaard, Paul, White, J. and Mortimer, N.(2008) The origin of intraplate volcanism on Zealandia [Talk] In: EGU General Assembly, 13.04.-18.04, Vienna, Austria... more
Timm, Christian, Hoernle, Kaj, Werner, Reinhard, Hauff, Folkmar, van den Bogaard, Paul, White, J. and Mortimer, N.(2008) The origin of intraplate volcanism on Zealandia [Talk] In: EGU General Assembly, 13.04.-18.04, Vienna, Austria (Unpublished)
Timm, Christian, Hoernle, Kaj, Hauff, Folkmar, van den Bogaard, Paul and Weaver, S.(2007) Crustal assimilation vs. mantle melts in lavas from Banks Peninsula, NZ [Talk] In: European Geosciences Union General Assembly 2007, 15.-20.04,... more
Timm, Christian, Hoernle, Kaj, Hauff, Folkmar, van den Bogaard, Paul and Weaver, S.(2007) Crustal assimilation vs. mantle melts in lavas from Banks Peninsula, NZ [Talk] In: European Geosciences Union General Assembly 2007, 15.-20.04, Vienna, Austria (Unpublished)
Jacques, Guillaume, Hoernle, Kaj, Wehrmann, Heidi, Garbe-Schönberg, Dieter, van den Bogaard, Paul, Hauff, Folkmar and Lara, Luis (2011) Along-Arc geochemical variations in the Southern Volcanic Zone, Chile [Talk] In: Goldschmidt... more
Jacques, Guillaume, Hoernle, Kaj, Wehrmann, Heidi, Garbe-Schönberg, Dieter, van den Bogaard, Paul, Hauff, Folkmar and Lara, Luis (2011) Along-Arc geochemical variations in the Southern Volcanic Zone, Chile [Talk] In: Goldschmidt Conference 2011, 14.-19.08. ...
The east-west-trending Christmas Island Seamount Province (CHRISP, 1800x600 km) in the northeastern Indian Ocean is elongated orthogonal to present-day plate motion, posing the question if a mantle plume formed this volcanic belt. Here we... more
The east-west-trending Christmas Island Seamount Province (CHRISP, 1800x600 km) in the northeastern Indian Ocean is elongated orthogonal to present-day plate motion, posing the question if a mantle plume formed this volcanic belt. Here we report the first age (Ar/Ar) ...
Timm, Christian, Hoernle, Kaj, Hauff, Folkmar, van den Bogaard, Paul, White, J. and Weaver, S.(2007) The origin of intraplate volcanism in New Zealand?[Invited talk] In: Seminar presentation at the PGP, University of Oslo, 22.03, Oslo... more
Timm, Christian, Hoernle, Kaj, Hauff, Folkmar, van den Bogaard, Paul, White, J. and Weaver, S.(2007) The origin of intraplate volcanism in New Zealand?[Invited talk] In: Seminar presentation at the PGP, University of Oslo, 22.03, Oslo (Unpublished)
The Central American Volcanic Arc (CAVA) has been subject of intensive research over the past decades, leading to a large variety of different models for the origin of CAVA lavas with various source components. Based on a comprehensive... more
The Central American Volcanic Arc (CAVA) has been subject of intensive research over the past decades, leading to a large variety of different models for the origin of CAVA lavas with various source components. Based on a comprehensive new geochemical data set (ie major and ...
The oldest (> 70 Ma) seamounts in the Emperor Ridge (Meiji and Detroit) comprise lavas with trace element and isotope compositions that approach depleted MORB, unlike the younger (< 70 Ma) lavas related to the Hawaiian hotspot.... more
The oldest (> 70 Ma) seamounts in the Emperor Ridge (Meiji and Detroit) comprise lavas with trace element and isotope compositions that approach depleted MORB, unlike the younger (< 70 Ma) lavas related to the Hawaiian hotspot. However, the depleted MORB-...
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The Walvis Ridge is one of the few hotspot tracks in the world that is apparently continuous from the active hotspot to a LIP that may mark its inception. The temporal and spatial relationship between the Walvis Ridge and the rapidly... more
The Walvis Ridge is one of the few hotspot tracks in the world that is apparently continuous from the active hotspot to a LIP that may mark its inception. The temporal and spatial relationship between the Walvis Ridge and the rapidly emplaced Paranà-Etendeka CFB is therefore widely considered a primary source of evidence supporting the starting plume head model (Duncan & Richards, 1991) for LIPs. A key prediction of this model is that the ~132 Myr old Etendeka (Renne et al., 1996) CFB (plume head) was immediately followed by the onset of Walvis Ridge volcanism (plume tail). The incubation plume model, assuming long term plume activity prior to rifting, makes no such prediction (Kent et al., 1992). Thus, measuring the age and volcanic propagation rate along Walvis Ridge and establishing the connection to the CFB is a crucial part of testing between the starting plume and incubation plume models. But the Walvis Ridge remains poorly sampled and dated, despite its pivotal importance in the global array of hotspots (mantle plumes) as the main constrain on African plate motion relative to plume hotspots. Initial dating of Walvis Ridge samples seemed to support a close temporal relationship between the Walvis Ridge and the CFB (O'Connor & Duncan, 1990, O'Connor & Le Roex, 1992). But later 40Ar/39Ar dating of the St Helena Seamount Chain raised the possibility that the oldest part of the ridge is significantly younger than the Etendeka CFB (O'Connor et al., 1999). If this discrepancy can be confirmed, it would imply that the melting anomaly responsible for the Walvis Ridge and Paranà-Etendeka CFB was not a steady-state process (e.g., incubating plume). The importance of this issue is emphasized by results of recent studies of Antarctic tectonics, which imply that rifting between South America and Africa began at ~160 My ago (Jokat et al., 2003) and that the CFBs are a response to ~30 Myr of rifting above hotspots such as Tristan, Shona, Discovery (and St. Helena) located under Gondwana.
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Abstract Although most Central American magmas have a typical arc geochemical signature, magmas in southern Central America have isotopic and trace element compositions with an OIB affinity, similar to the Galapagos hotspot lavas. Our new... more
Abstract Although most Central American magmas have a typical arc geochemical signature, magmas in southern Central America have isotopic and trace element compositions with an OIB affinity, similar to the Galapagos hotspot lavas. Our new data for ...
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... PETER MICHAEL 1, DAVID GRAHAM 2, DAVID CHRISTIE 3, KAJ HOERNLE 4, FOLKMAR HAUFF 4, BARRY HANAN 5 1Dept. ... of Alaska, Fairbanks, AK, 99775, dchristie@guru.uaf.edu 4IFM-GEOMAR, Universität Kiel, Kiel, Germany khoernle@ifm-geomar.de... more
... PETER MICHAEL 1, DAVID GRAHAM 2, DAVID CHRISTIE 3, KAJ HOERNLE 4, FOLKMAR HAUFF 4, BARRY HANAN 5 1Dept. ... of Alaska, Fairbanks, AK, 99775, dchristie@guru.uaf.edu 4IFM-GEOMAR, Universität Kiel, Kiel, Germany khoernle@ifm-geomar.de 5Dept. ...
Research Interests: Earth Sciences, Geochemistry, Petrology and Geochemistry, Geochronology & isotope Geology, Mid Ocean Ridge, and 11 moreSilica, New Zealand, Physical sciences, First-Order Logic, Partial Melting, Pb isotopes, Earth and Planetary Science, First Order Logic, Intraplate Volcanism, Volcanic Rock, and Trace element
Hoernle, Kaj, Hauff, Folkmar, Werner, Reinhard, van den Bogaard, Paul, Timm, Christian, Coffin, M., White, J. and Kuroda, J. (2009) Signifikanz und Ursprung ozeanischer Plateaus: die Bedeutung einer mehrphasigen Entstehungsgeschichte der... more
Hoernle, Kaj, Hauff, Folkmar, Werner, Reinhard, van den Bogaard, Paul, Timm, Christian, Coffin, M., White, J. and Kuroda, J. (2009) Signifikanz und Ursprung ozeanischer Plateaus: die Bedeutung einer mehrphasigen Entstehungsgeschichte der Manihikiund Hikurangiplateaus (SO168, SO193) [Talk] In: SONNE Statusseminar "Meeresforschung mit FS SONNE", 12.02.-13.02.2009, Bremerhaven. ... Full text not available from this repository.
We present 40Ar/39Ar age and geochemical (major and trace element and Sr–Nd–Hf–Pb isotope) data from submarine samples recovered from the basement of the Manihiki Plateau during the R/V Sonne research expedition SO193. The samples,... more
We present 40Ar/39Ar age and geochemical (major and trace element and Sr–Nd–Hf–Pb isotope) data from submarine samples recovered from the basement of the Manihiki Plateau during the R/V Sonne research expedition SO193. The samples, predominately tholeiites, with minor occurrences of basaltic andesites and hawaiites, give a mean age of 124.6±1.6 Ma from four different localities on the plateau. Based on TiO2 content, we define two groups of volcanic rocks that differ in trace element and isotopic compositions. Partial melting ...
Research Interests: Earth Sciences, Petrology and Geochemistry, Geochronology & isotope Geology, Large Igneous Provinces, Physical sciences, and 10 morePartial Melting, Pb isotopes, Large Igneous Province, Intraplate Volcanism, Mantle plume, Volatiles, Volcanic Rock, Trace element, Water Content, and Melting Temperature
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Research Interests: Earth Sciences, Geochemistry, Physical sciences, Mantle plumes, Pb isotopes, and 12 moreRare Earth Element Mineralization, First record, Hot Spot, Rare Earth, Large Igneous Province, Mantle Sources, Mantle plume, Low Temperature, Volcanic Rock, Trace element, Caribbean Plate Tectonic Evolution, and Hf isotopes
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"Intraplate volcanism was widespread and occurred continuously throughout the Cenozoic on the New Zealand micro-continent, Zealandia, forming two volcanic endmembers: (1) monogenetic volcanic fields; (2) composite shield volcanoes.The... more
"Intraplate volcanism was widespread and occurred continuously
throughout the Cenozoic on the New Zealand micro-continent,
Zealandia, forming two volcanic endmembers: (1) monogenetic volcanic fields; (2) composite shield volcanoes.The most prominent volcanic landforms on the South Island of New Zealand are the two composite shield volcanoes (Lyttelton and Akaroa) forming the Banks Peninsula.We present new 40Ar/39Ar age and geochemical (major and trace element and Sr-Nd-Pb-Hf-O isotope) data for these Miocene endmembers of intraplate volcanism. Although volcanism persisted for ~7 Myr on Banks Peninsula, both shield volcanoes primarily formed over an 1Myr interval with small volumes of late-stage volcanism continuing for ~15 Myr after formation of the shields. Compared with normal Pacific mid-ocean ridge basalts (P-MORB), the low-silica (picritic to basanitic to alkali basaltic) Akaroa mafic volcanic rocks (9.4-6.8 Ma) have higher incompatible trace element concentrations and Sr and Pb isotope ratios but lower d18O (4.6-4.9) and Nd and Hf isotope ratios than ocean island basalts (OIB) or high time-integrated U/Pb HIMU-type signatures, consistent with the presence of a hydrothermally altered recycled oceanic crustal component in their source. Elevated CaO, MnO and Cr contents in the HIMU-type low-silica lavas, however, point to a peridotitic rather than a pyroxenitic or eclogitic source. To explain the decoupling between major elements on the one hand and incompatible elements and isotopic compositions on the other, we propose that the upwelling asthenospheric source consists of carbonated eclogite in a peridotite matrix. Melts from carbonated eclogite generated at the base of the melt column metasomatized the surrounding peridotite before it crossed its solidus. Higher in the melt column the metasomatized peridotite melted to form the Akaroa low-silica melts. The older (12.3-10.4 Ma), high-silica (tholeiitic to alkali basaltic) Lyttelton mafic volcanic rocks have low CaO, MnO and Cr abundances suggesting that they were at least partially derived from a source with residual pyroxenite.They also have lower incompatible element abundances, higher fluid-mobile to fluid-immobile trace element ratios, higher d18O, and more radiogenic Sr but less radiogenic Pb-Nd-Hf isotopic compositions than the Akaroa volcanic rocks and display enriched (EMII-type) trace element and isotopic compositions. Mixing of asthenospheric (Akaroa-type) melts with lithospheric melts from pyroxenite formed duringMesozoic subduction along the Gondwana margin and crustal melts can explain the composition of the Lyttelton volcano basalts.Two successive lithospheric detachment/delamination events in the form of Rayleigh^
Taylor instabilities could have triggered the upwelling and related decompression melting leading to the formation of the Lyttelton (first, smaller detachment event) and Akaroa (second, more extensive detachment event) volcanoes."
throughout the Cenozoic on the New Zealand micro-continent,
Zealandia, forming two volcanic endmembers: (1) monogenetic volcanic fields; (2) composite shield volcanoes.The most prominent volcanic landforms on the South Island of New Zealand are the two composite shield volcanoes (Lyttelton and Akaroa) forming the Banks Peninsula.We present new 40Ar/39Ar age and geochemical (major and trace element and Sr-Nd-Pb-Hf-O isotope) data for these Miocene endmembers of intraplate volcanism. Although volcanism persisted for ~7 Myr on Banks Peninsula, both shield volcanoes primarily formed over an 1Myr interval with small volumes of late-stage volcanism continuing for ~15 Myr after formation of the shields. Compared with normal Pacific mid-ocean ridge basalts (P-MORB), the low-silica (picritic to basanitic to alkali basaltic) Akaroa mafic volcanic rocks (9.4-6.8 Ma) have higher incompatible trace element concentrations and Sr and Pb isotope ratios but lower d18O (4.6-4.9) and Nd and Hf isotope ratios than ocean island basalts (OIB) or high time-integrated U/Pb HIMU-type signatures, consistent with the presence of a hydrothermally altered recycled oceanic crustal component in their source. Elevated CaO, MnO and Cr contents in the HIMU-type low-silica lavas, however, point to a peridotitic rather than a pyroxenitic or eclogitic source. To explain the decoupling between major elements on the one hand and incompatible elements and isotopic compositions on the other, we propose that the upwelling asthenospheric source consists of carbonated eclogite in a peridotite matrix. Melts from carbonated eclogite generated at the base of the melt column metasomatized the surrounding peridotite before it crossed its solidus. Higher in the melt column the metasomatized peridotite melted to form the Akaroa low-silica melts. The older (12.3-10.4 Ma), high-silica (tholeiitic to alkali basaltic) Lyttelton mafic volcanic rocks have low CaO, MnO and Cr abundances suggesting that they were at least partially derived from a source with residual pyroxenite.They also have lower incompatible element abundances, higher fluid-mobile to fluid-immobile trace element ratios, higher d18O, and more radiogenic Sr but less radiogenic Pb-Nd-Hf isotopic compositions than the Akaroa volcanic rocks and display enriched (EMII-type) trace element and isotopic compositions. Mixing of asthenospheric (Akaroa-type) melts with lithospheric melts from pyroxenite formed duringMesozoic subduction along the Gondwana margin and crustal melts can explain the composition of the Lyttelton volcano basalts.Two successive lithospheric detachment/delamination events in the form of Rayleigh^
Taylor instabilities could have triggered the upwelling and related decompression melting leading to the formation of the Lyttelton (first, smaller detachment event) and Akaroa (second, more extensive detachment event) volcanoes."