John Sinton - Academia.edu (original) (raw)
Papers by John Sinton
Major and trace element analyses of submarine volcanic rocks from Ka'ena Ridge, O'ahu, Ha... more Major and trace element analyses of submarine volcanic rocks from Ka'ena Ridge, O'ahu, Hawai'i. Dataset includes glass analyses by EMP and whole rock analyses by XRF and ICP-MS.
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AGU Fall Meeting Abstracts, Dec 1, 2003
Recent studies propose that the axial high topography observed at intermediate- and fast-spreadin... more Recent studies propose that the axial high topography observed at intermediate- and fast-spreading mid-ocean ridges (MORs) reflects the thermal structure and stress state of the MOR lithosphere. Hotspot related variations in thermal structure along the western Galapagos Spreading Center (GSC) thus offer an opportunity to test some of the proposed causes for axial high topography. Along the intermediate rate spreading
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AGUSM, May 1, 2002
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AGU Fall Meeting Abstracts, Dec 16, 2015
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Journal of Geophysical Research, Oct 1, 2004
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AGUFM, Dec 1, 2011
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AGUFM, Dec 1, 2011
ABSTRACT The intermediate-spreading-rate Galapagos Spreading Center (GSC) experiences decreasing ... more ABSTRACT The intermediate-spreading-rate Galapagos Spreading Center (GSC) experiences decreasing magma supply along axis with increasing distance from the nearby Galapagos hotspot. This allows us to explore the effects of variable magma supply on eruptive frequency, size, and style. Two contrasting sites on the GSC were mapped using high-resolution swath bathymetry, submersible observations, and camera tow photography. Individual eruptive units have been identified on the basis of these data and observations, as well sample geochemistry. In order to construct an eruptive history and to make broader interpretations regarding eruptive processes, it is necessary to place relative and absolute age constraints on these units. We present age determinations derived from geomagnetic paleointensity experiments at one of the study sites, centered at ~91°55'W, where increased magma supply from the hotspot results in an axial high. Due to the near monotonic decrease in geomagnetic paleointensity over the past ~500+ years, it is possible to infer relative age and to place approximate age constraints on eruptive units on the basis of their experimentally-determined paleointensity. Four of the largest identified units have been selected as a test case. Results suggest that the youngest flow is approximately 40 ± 30 years old. This flow unit is ~5 km long by 1 km wide, centered on the rise axis. An older flow (~180 ± 30 years old), also centered along the rise axis, lies to the west and its ~7 km along-axis exposure is interrupted by a large, flat-topped seamount. A number of active hydrothermal chimneys sit atop this flow unit, the heat source for which we infer to be related to the younger flow to the east or to a more recent shallow intrusion. The oldest documented flow is roughly 400 years old and is exposed slightly off-axis to the north of the two younger flows. The paleointensity-derived flow ages are consistent with available geological constraints on relative age. Based on these geologic constraints, there appear to be at least four flows younger than the oldest dated flow, suggesting an upper limit on the recurrence interval of less than ~80 yrs. This compares to known historical recurrence intervals of ~13 years on the fast-spreading East Pacific Rise at 9°50'N and ~10 years and on the intermediate-spreading CoAxial segment of the Juan de Fuca Ridge, which is also influenced by the nearby Cobb hotspot.
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AGUFM, Dec 1, 2013
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The 84th Annual Meeting of the Society for American Archaeology, 2019
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AGU Fall Meeting Abstracts, Dec 1, 2012
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Geoarchaeology
We examined 2947 basalt and volcanic glass artifacts from 38 sites in leeward Kohala. Nondestruct... more We examined 2947 basalt and volcanic glass artifacts from 38 sites in leeward Kohala. Nondestructive energy‐dispersive X‐ray fluorescence provided initial geochemical characterizations. Wavelength‐dispersive X‐ray fluorescence (WDXRF) and thermal ionization mass spectrometry (TIMS) analyses were completed on samples from ambiguously sourced groups. No more than 13.9% of the probable and definite adze‐related debitage originated in leeward Kohala. Notably absent are lithic materials from the nearby Pololū Adze Quarry in windward Kohala. Material from the more distant Mauna Kea Adze Quarry accounts for 41.6% of the adze debitage. Another 38.8% of the adze debitage matches with a tholeiitic source or sources long assumed to be Kīlauea Volcano in Kaʻū, but WDXRF and TIMS isotopic data do not support a Kīlauea source. Centralized adze production and distribution networks best explain adze distribution. Scoria abraders appear to have been regularly transported from the Kona district to le...
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Journal of Petrology
To deconvolve contributions from the four overlapping hotspots that form the “hotspot highway” on... more To deconvolve contributions from the four overlapping hotspots that form the “hotspot highway” on the Pacific plate—Samoa, Rarotonga, Arago-Rurutu, and Macdonald—we geochemically characterize and/or date (by the 40Ar/39Ar method) a suite of lavas sampled from the eastern region of the Samoan hotspot and the region “downstream” of the Samoan hotspot track. We find that Papatua seamount, located ~60 km south of the axis of the Samoan hotspot track, has lavas with both a HIMU (high μ = 238U/204Pb) composition (206Pb/204Pb = 20.0), previously linked to one of the Cook-Austral hotspots, and an enriched mantle I (EM1) composition, which we interpret to be rejuvenated and Samoan in origin. We show that these EM1 rejuvenated lavas at Papatua are geochemically similar to rejuvenated volcanism on Samoan volcanoes and suggest that flexural uplift, caused by tectonic forces associated with the nearby Tonga trench, triggered a new episode of melting of Samoan mantle material that had previously ...
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Programme and Abstracts the Volocanological Society of Japan, 2004
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Programme and abstracts the Volcanological Society of Japan, 2008
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Samples and geological observations of the submarine Ka'ena Ridge, northwest of the island of... more Samples and geological observations of the submarine Ka'ena Ridge, northwest of the island of O'ahu, Hawai'i indicate multiple episodes of volcanic and structural evolution that is inconsistent with this feature simply representing the NW extension of a rift zone of the nearby, subaerial Wai'anae Volcano of O'ahu. The topographic axis of Ka'ena Ridge is displaced to the north of the prominent Wai'anae NW Rift Zone and Ka'ena Ridge is surmounted by two broad lava shield structures, at least one of which is composed of subaerial tholeitic lava at a depth of 700 m. Preliminary K-Ar ages of two samples from Ka'ena Ridge are up to 0.5 m.y. younger than associated lavas on the Wai'anae Volcano. To further investigate the volcanic and structural evolution of Ka'ena Ridge we conducted a series of dives with the ROV Jason during R/V Kilo Moana cruise KM1116 in 2011. Preliminary results from this cruise and initial geochemical investigations are: 1)...
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Major and trace element analyses of submarine volcanic rocks from Ka'ena Ridge, O'ahu, Ha... more Major and trace element analyses of submarine volcanic rocks from Ka'ena Ridge, O'ahu, Hawai'i. Dataset includes glass analyses by EMP and whole rock analyses by XRF and ICP-MS.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
AGU Fall Meeting Abstracts, Dec 1, 2003
Recent studies propose that the axial high topography observed at intermediate- and fast-spreadin... more Recent studies propose that the axial high topography observed at intermediate- and fast-spreading mid-ocean ridges (MORs) reflects the thermal structure and stress state of the MOR lithosphere. Hotspot related variations in thermal structure along the western Galapagos Spreading Center (GSC) thus offer an opportunity to test some of the proposed causes for axial high topography. Along the intermediate rate spreading
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AGUSM, May 1, 2002
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AGU Fall Meeting Abstracts, Dec 16, 2015
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Journal of Geophysical Research, Oct 1, 2004
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AGUFM, Dec 1, 2011
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AGUFM, Dec 1, 2011
ABSTRACT The intermediate-spreading-rate Galapagos Spreading Center (GSC) experiences decreasing ... more ABSTRACT The intermediate-spreading-rate Galapagos Spreading Center (GSC) experiences decreasing magma supply along axis with increasing distance from the nearby Galapagos hotspot. This allows us to explore the effects of variable magma supply on eruptive frequency, size, and style. Two contrasting sites on the GSC were mapped using high-resolution swath bathymetry, submersible observations, and camera tow photography. Individual eruptive units have been identified on the basis of these data and observations, as well sample geochemistry. In order to construct an eruptive history and to make broader interpretations regarding eruptive processes, it is necessary to place relative and absolute age constraints on these units. We present age determinations derived from geomagnetic paleointensity experiments at one of the study sites, centered at ~91°55'W, where increased magma supply from the hotspot results in an axial high. Due to the near monotonic decrease in geomagnetic paleointensity over the past ~500+ years, it is possible to infer relative age and to place approximate age constraints on eruptive units on the basis of their experimentally-determined paleointensity. Four of the largest identified units have been selected as a test case. Results suggest that the youngest flow is approximately 40 ± 30 years old. This flow unit is ~5 km long by 1 km wide, centered on the rise axis. An older flow (~180 ± 30 years old), also centered along the rise axis, lies to the west and its ~7 km along-axis exposure is interrupted by a large, flat-topped seamount. A number of active hydrothermal chimneys sit atop this flow unit, the heat source for which we infer to be related to the younger flow to the east or to a more recent shallow intrusion. The oldest documented flow is roughly 400 years old and is exposed slightly off-axis to the north of the two younger flows. The paleointensity-derived flow ages are consistent with available geological constraints on relative age. Based on these geologic constraints, there appear to be at least four flows younger than the oldest dated flow, suggesting an upper limit on the recurrence interval of less than ~80 yrs. This compares to known historical recurrence intervals of ~13 years on the fast-spreading East Pacific Rise at 9°50'N and ~10 years and on the intermediate-spreading CoAxial segment of the Juan de Fuca Ridge, which is also influenced by the nearby Cobb hotspot.
Bookmarks Related papers MentionsView impact
AGUFM, Dec 1, 2013
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The 84th Annual Meeting of the Society for American Archaeology, 2019
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AGU Fall Meeting Abstracts, Dec 1, 2012
Bookmarks Related papers MentionsView impact
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Geoarchaeology
We examined 2947 basalt and volcanic glass artifacts from 38 sites in leeward Kohala. Nondestruct... more We examined 2947 basalt and volcanic glass artifacts from 38 sites in leeward Kohala. Nondestructive energy‐dispersive X‐ray fluorescence provided initial geochemical characterizations. Wavelength‐dispersive X‐ray fluorescence (WDXRF) and thermal ionization mass spectrometry (TIMS) analyses were completed on samples from ambiguously sourced groups. No more than 13.9% of the probable and definite adze‐related debitage originated in leeward Kohala. Notably absent are lithic materials from the nearby Pololū Adze Quarry in windward Kohala. Material from the more distant Mauna Kea Adze Quarry accounts for 41.6% of the adze debitage. Another 38.8% of the adze debitage matches with a tholeiitic source or sources long assumed to be Kīlauea Volcano in Kaʻū, but WDXRF and TIMS isotopic data do not support a Kīlauea source. Centralized adze production and distribution networks best explain adze distribution. Scoria abraders appear to have been regularly transported from the Kona district to le...
Bookmarks Related papers MentionsView impact
Journal of Petrology
To deconvolve contributions from the four overlapping hotspots that form the “hotspot highway” on... more To deconvolve contributions from the four overlapping hotspots that form the “hotspot highway” on the Pacific plate—Samoa, Rarotonga, Arago-Rurutu, and Macdonald—we geochemically characterize and/or date (by the 40Ar/39Ar method) a suite of lavas sampled from the eastern region of the Samoan hotspot and the region “downstream” of the Samoan hotspot track. We find that Papatua seamount, located ~60 km south of the axis of the Samoan hotspot track, has lavas with both a HIMU (high μ = 238U/204Pb) composition (206Pb/204Pb = 20.0), previously linked to one of the Cook-Austral hotspots, and an enriched mantle I (EM1) composition, which we interpret to be rejuvenated and Samoan in origin. We show that these EM1 rejuvenated lavas at Papatua are geochemically similar to rejuvenated volcanism on Samoan volcanoes and suggest that flexural uplift, caused by tectonic forces associated with the nearby Tonga trench, triggered a new episode of melting of Samoan mantle material that had previously ...
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Programme and Abstracts the Volocanological Society of Japan, 2004
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Programme and abstracts the Volcanological Society of Japan, 2008
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Samples and geological observations of the submarine Ka'ena Ridge, northwest of the island of... more Samples and geological observations of the submarine Ka'ena Ridge, northwest of the island of O'ahu, Hawai'i indicate multiple episodes of volcanic and structural evolution that is inconsistent with this feature simply representing the NW extension of a rift zone of the nearby, subaerial Wai'anae Volcano of O'ahu. The topographic axis of Ka'ena Ridge is displaced to the north of the prominent Wai'anae NW Rift Zone and Ka'ena Ridge is surmounted by two broad lava shield structures, at least one of which is composed of subaerial tholeitic lava at a depth of 700 m. Preliminary K-Ar ages of two samples from Ka'ena Ridge are up to 0.5 m.y. younger than associated lavas on the Wai'anae Volcano. To further investigate the volcanic and structural evolution of Ka'ena Ridge we conducted a series of dives with the ROV Jason during R/V Kilo Moana cruise KM1116 in 2011. Preliminary results from this cruise and initial geochemical investigations are: 1)...
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