This data set includes the tied, raw gravity measurements and free-air gravity anomaly values col... more This data set includes the tied, raw gravity measurements and free-air gravity anomaly values collected using a LaCoste and Romberg model G type gravimeter during a 2012 survey of Santa Cruz Island and a 2016 survey of San Cristobal Island. Gravity measurements from the Santa Cruz survey were tied to a previous measurement at the Charles Darwin Station dock in Puerto Ayora (Ryland, 1971) and for the Santa Cristobal survey to a US Navy tie on a concrete pier in Baltra, Santa Cruz (0° 26' 3'' S, 90° 17' 1'' W). Latitude, longitude, and elevation were collected at each measurement location using a Trimble R7 GPS system. The raw gravity measurements were reduced to a Free Air Anomaly (FAA) by removing instrument drift (~0.01 mGal/day), the effect of elevation above sea level, and the WGS-84 reference ellipsoid. The data file is in ASCII format and was generated as part of the projects called Interdisciplinary Studies of the Galapagos Earth System, and Next Genera...
This dataset contains major and trace element analyses of volcanic rocks from the Galapagos Archi... more This dataset contains major and trace element analyses of volcanic rocks from the Galapagos Archipelago, selected from across the region to be representative of the geochemical variation in the hotspot system. The goal of the project is twofold: a) to assemble a dataset of radiogenic isotope ratios performed at a high and consistent level of precision; and b) to compare radiogenic isotope ratios with recent Hawaii isotopic signatures. To build a complete dataset, we selected the samples from across the archipelago from existing collections, in addition to new samples from Espanola, San Cristobal, and Santa Cruz Islands. Any samples that were missing published major and full suites of trace element data were also analyzed for those missing data. The samples analyzed at Colgate University for majors by XRF and for trace elements by ICP-MS are included here (i.e., new data).
Towed MR1 sidescan and phase bathymetry data for the Northern Galapagos, collected in 2010 during... more Towed MR1 sidescan and phase bathymetry data for the Northern Galapagos, collected in 2010 during Melville cruise MV1007 (investigator Karen Harpp). These are the most-evolved processed data files created during the cruise and include corrected towfish navigation. These data files were generated by the Hawaii Mapping Research Group (HMRG) and are in the HMRG Bathymetry/Sidescan (BS) format. The data files were acquired as part of the project called Plume-Ridge Interaction in the Northern Galapagos: Understanding mantle-lithosphere dynamics through geochemistry, geophysical mapping, and gravity modeling, with funding provided by NSF grant OCE09-26491.
This data set was acquired with a ship-based Kongsberg EM122 Multibeam Sonar system during Melvil... more This data set was acquired with a ship-based Kongsberg EM122 Multibeam Sonar system during Melville expedition MV1007 conducted in 2010 (Chief Scientist: Dr. Karen Harpp). These data files are of NetCDF Grid format and include gridded Sidescan data and were processed after data collection. Data were acquired as part of the project(s): FLAMINGO (Formation of Lineaments and Anomalous Magmatism In the Northern Galápagos Ocean), and funding was provided by NSF grant(s): OCE09-26491. This data was cited by Mittelstaedt et al., 2012.
Hekla is an elongate volcano that lies at the intersection of the South Iceland Seismic Zone and ... more Hekla is an elongate volcano that lies at the intersection of the South Iceland Seismic Zone and the Eastern Volcanic Zone. We report major and trace element, oxygen isotopic, and H2O analyses on rocks, glass, melt inclusions, and minerals from almost all of the historical lavas and tephra deposits. This new data set confirms the remarkable observation that not only are many eruptions compositionally zoned from felsic to mafic, but the extent of zoning relates directly to the length of repose since the previous eruption. Compositional data are consistent with the origin of the basaltic andesites and andesites by fractional crystallization, with no measurable crustal interaction once basaltic andesite has been produced. Although the 1104 C.E. Plinian rhyolite and 1158 C.E. dacite are also created by fractional crystallization, uranium-thorium isotopic disequilibria measured by others require that it evolved in a separate body, where it is stored in a molten state for >104 years. C...
Seawater (234)U/(238)U provides global-scale information about continental weathering and is vita... more Seawater (234)U/(238)U provides global-scale information about continental weathering and is vital for marine uranium-series geochronology. Existing evidence supports an increase in (234)U/(238)U since the last glacial period, but the timing and amplitude of its variability has been poorly constrained. Here we report two seawater (234)U/(238)U records based on well-preserved deep-sea corals from the low-latitude Atlantic and Pacific Oceans. The Atlantic (234)U/(238)U started to increase before major sea-level rise and overshot the modern value by 3 per mil during the early deglaciation. Deglacial (234)U/(238)U in the Pacific converged with that in the Atlantic after the abrupt resumption of Atlantic meridional overturning. We suggest that ocean mixing and early deglacial release of excess (234)U from enhanced subglacial melting of the Northern Hemisphere ice sheets have driven the observed (234)U/(238)U evolution.
Sierra Negra volcano began erupting on 22 October 2005, after a repose of 26 years. A plume of as... more Sierra Negra volcano began erupting on 22 October 2005, after a repose of 26 years. A plume of ash and steam more than 13 km high accompanied the initial phase of the eruption and was quickly followed by a ~2-km-long curtain of lava fountains. The eruptive fissure opened inside the north rim of the caldera, on the opposite side of the caldera from an active fault system that experienced an mb 4.6 earthquake and ~84 cm of uplift on 16 April 2005. The main products of the eruption were an `a`a flow that ponded in the caldera and clastigenic lavas that flowed down the north flank. The `a`a flow grew in an unusual way. Once it had established most of its aerial extent, the interior of the flow was fed via a perched lava pond, causing inflation of the `a`a. This pressurized fluid interior then fed pahoehoe breakouts along the margins of the flow, many of which were subsequently overridden by `a`a, as the crust slowly spread from the center of the pond and tumbled over the pahoehoe. The curtain of lava fountains coalesced with time, and by day 4, only one vent was erupting. The effusion rate slowed from day 7 until the eruption’s end two days later on 30 October. Although the caldera floor had inflated by ~5 m since 1992, and the rate of inflation had accelerated since 2003, there was no transient deformation in the hours or days before the eruption. During the 8 days of the eruption, GPS and InSAR data show that the caldera floor deflated ~5 m, and the volcano contracted horizontally ~6 m. The total eruptive volume is estimated as being ~150×106 m3. The opening-phase tephra is more evolved than the eruptive products that followed. The compositional variation of tephra and lava sampled over the course of the eruption is attributed to eruption from a zoned sill that lies 2.1 km beneath the caldera floor.
This data set includes the tied, raw gravity measurements and free-air gravity anomaly values col... more This data set includes the tied, raw gravity measurements and free-air gravity anomaly values collected using a LaCoste and Romberg model G type gravimeter during a 2012 survey of Santa Cruz Island and a 2016 survey of San Cristobal Island. Gravity measurements from the Santa Cruz survey were tied to a previous measurement at the Charles Darwin Station dock in Puerto Ayora (Ryland, 1971) and for the Santa Cristobal survey to a US Navy tie on a concrete pier in Baltra, Santa Cruz (0° 26' 3'' S, 90° 17' 1'' W). Latitude, longitude, and elevation were collected at each measurement location using a Trimble R7 GPS system. The raw gravity measurements were reduced to a Free Air Anomaly (FAA) by removing instrument drift (~0.01 mGal/day), the effect of elevation above sea level, and the WGS-84 reference ellipsoid. The data file is in ASCII format and was generated as part of the projects called Interdisciplinary Studies of the Galapagos Earth System, and Next Genera...
This dataset contains major and trace element analyses of volcanic rocks from the Galapagos Archi... more This dataset contains major and trace element analyses of volcanic rocks from the Galapagos Archipelago, selected from across the region to be representative of the geochemical variation in the hotspot system. The goal of the project is twofold: a) to assemble a dataset of radiogenic isotope ratios performed at a high and consistent level of precision; and b) to compare radiogenic isotope ratios with recent Hawaii isotopic signatures. To build a complete dataset, we selected the samples from across the archipelago from existing collections, in addition to new samples from Espanola, San Cristobal, and Santa Cruz Islands. Any samples that were missing published major and full suites of trace element data were also analyzed for those missing data. The samples analyzed at Colgate University for majors by XRF and for trace elements by ICP-MS are included here (i.e., new data).
Towed MR1 sidescan and phase bathymetry data for the Northern Galapagos, collected in 2010 during... more Towed MR1 sidescan and phase bathymetry data for the Northern Galapagos, collected in 2010 during Melville cruise MV1007 (investigator Karen Harpp). These are the most-evolved processed data files created during the cruise and include corrected towfish navigation. These data files were generated by the Hawaii Mapping Research Group (HMRG) and are in the HMRG Bathymetry/Sidescan (BS) format. The data files were acquired as part of the project called Plume-Ridge Interaction in the Northern Galapagos: Understanding mantle-lithosphere dynamics through geochemistry, geophysical mapping, and gravity modeling, with funding provided by NSF grant OCE09-26491.
This data set was acquired with a ship-based Kongsberg EM122 Multibeam Sonar system during Melvil... more This data set was acquired with a ship-based Kongsberg EM122 Multibeam Sonar system during Melville expedition MV1007 conducted in 2010 (Chief Scientist: Dr. Karen Harpp). These data files are of NetCDF Grid format and include gridded Sidescan data and were processed after data collection. Data were acquired as part of the project(s): FLAMINGO (Formation of Lineaments and Anomalous Magmatism In the Northern Galápagos Ocean), and funding was provided by NSF grant(s): OCE09-26491. This data was cited by Mittelstaedt et al., 2012.
Hekla is an elongate volcano that lies at the intersection of the South Iceland Seismic Zone and ... more Hekla is an elongate volcano that lies at the intersection of the South Iceland Seismic Zone and the Eastern Volcanic Zone. We report major and trace element, oxygen isotopic, and H2O analyses on rocks, glass, melt inclusions, and minerals from almost all of the historical lavas and tephra deposits. This new data set confirms the remarkable observation that not only are many eruptions compositionally zoned from felsic to mafic, but the extent of zoning relates directly to the length of repose since the previous eruption. Compositional data are consistent with the origin of the basaltic andesites and andesites by fractional crystallization, with no measurable crustal interaction once basaltic andesite has been produced. Although the 1104 C.E. Plinian rhyolite and 1158 C.E. dacite are also created by fractional crystallization, uranium-thorium isotopic disequilibria measured by others require that it evolved in a separate body, where it is stored in a molten state for >104 years. C...
Seawater (234)U/(238)U provides global-scale information about continental weathering and is vita... more Seawater (234)U/(238)U provides global-scale information about continental weathering and is vital for marine uranium-series geochronology. Existing evidence supports an increase in (234)U/(238)U since the last glacial period, but the timing and amplitude of its variability has been poorly constrained. Here we report two seawater (234)U/(238)U records based on well-preserved deep-sea corals from the low-latitude Atlantic and Pacific Oceans. The Atlantic (234)U/(238)U started to increase before major sea-level rise and overshot the modern value by 3 per mil during the early deglaciation. Deglacial (234)U/(238)U in the Pacific converged with that in the Atlantic after the abrupt resumption of Atlantic meridional overturning. We suggest that ocean mixing and early deglacial release of excess (234)U from enhanced subglacial melting of the Northern Hemisphere ice sheets have driven the observed (234)U/(238)U evolution.
Sierra Negra volcano began erupting on 22 October 2005, after a repose of 26 years. A plume of as... more Sierra Negra volcano began erupting on 22 October 2005, after a repose of 26 years. A plume of ash and steam more than 13 km high accompanied the initial phase of the eruption and was quickly followed by a ~2-km-long curtain of lava fountains. The eruptive fissure opened inside the north rim of the caldera, on the opposite side of the caldera from an active fault system that experienced an mb 4.6 earthquake and ~84 cm of uplift on 16 April 2005. The main products of the eruption were an `a`a flow that ponded in the caldera and clastigenic lavas that flowed down the north flank. The `a`a flow grew in an unusual way. Once it had established most of its aerial extent, the interior of the flow was fed via a perched lava pond, causing inflation of the `a`a. This pressurized fluid interior then fed pahoehoe breakouts along the margins of the flow, many of which were subsequently overridden by `a`a, as the crust slowly spread from the center of the pond and tumbled over the pahoehoe. The curtain of lava fountains coalesced with time, and by day 4, only one vent was erupting. The effusion rate slowed from day 7 until the eruption’s end two days later on 30 October. Although the caldera floor had inflated by ~5 m since 1992, and the rate of inflation had accelerated since 2003, there was no transient deformation in the hours or days before the eruption. During the 8 days of the eruption, GPS and InSAR data show that the caldera floor deflated ~5 m, and the volcano contracted horizontally ~6 m. The total eruptive volume is estimated as being ~150×106 m3. The opening-phase tephra is more evolved than the eruptive products that followed. The compositional variation of tephra and lava sampled over the course of the eruption is attributed to eruption from a zoned sill that lies 2.1 km beneath the caldera floor.
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