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...