A5018815834- Geological and Geochemical Analysis
- earthquake and tectonic studies
- Geology and Paleoclimatology Research
- Methane Hydrates and Related Phenomena
- High-pressure geophysics and materials
- Geochemistry and Geologic Mapping
- Geological and Geophysical Studies
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Astronomical Observations and Instrumentation
- Planetary Science and Exploration
- Hydrocarbon exploration and reservoir analysis
- Offshore Engineering and Technologies
- Geomagnetism and Paleomagnetism Studies
- Geological Studies and Exploration
- Spacecraft and Cryogenic Technologies
- Geological formations and processes
- Geological Modeling and Analysis
- Paleontology and Stratigraphy of Fossils
- Geological and Tectonic Studies in Latin America
- Seismic Imaging and Inversion Techniques
- Pleistocene-Era Hominins and Archaeology
- Drilling and Well Engineering
- Astronomy and Astrophysical Research
- Botany and Geology in Latin America and Caribbean
University of Iowa
2015-2024
International Ocean Discovery Program
2015
Geological Society of America
2006
University of Kansas
1998
University of Nevada, Reno
1998
University of California, Santa Cruz
1987
University of Arizona
1981-1984
Recent diving with the JAMSTEC Shinkai 6500 manned submersible in Mariana fore arc southeast of Guam has discovered that MORB‐like tholeiitic basalts crop out over large areas. These “fore‐arc basalts” (FAB) underlie boninites and overlie diabasic gabbroic rocks. Potential origins include eruption at a spreading center before subduction began or during near‐trench after began. FAB trace element patterns are similar to those MORB most Izu‐Bonin‐Mariana (IBM) back‐arc lavas. However, Ti/V Yb/V...
Articulating a comprehensive plate-tectonic theory requires understanding how new subduction zones form (subduction initiation). Because initiation is tectonomagmatic singularity with few active examples, reconstructing challenging. The lithosphere of many intra-oceanic forearcs preserves high-fidelity magmatic and stratigraphic record initiation. We have heretofore been remarkably ignorant this record, because the "naked forearcs" that expose crustal sections are distant from continents lie...
Research Article| April 01, 2014 Izu-Bonin-Mariana Forearc Crust as a Modern Ophiolite Analogue Osamu Ishizuka; Ishizuka 1Institute of Geology and Geoinformation, Geological Survey Japan/AIST, Central 7, 1-1-1, Higashi, Tsukuba, Ibaraki, 305-8567, JapanE-mail: o-ishizuka@aist.go.jp2IFREE, JAMSTEC, 2-15 Natsushima, Yokosuka, Kanagawa, 237-0061, Japan Search for other works by this author on: GSW Google Scholar Kenichiro Tani; Tani 2IFREE, Mark K. Reagan 3Department Geoscience, 121 Trowbridge...
Research Article| February 01, 2014 Heading down early on? Start of subduction on Earth Simon Turner; Turner * 1Department and Planetary Sciences, Macquarie University, Sydney, Australia *E-mails: simon.turner@mq.edu.au; tracy.rushmer@mq.edu.au; mark-reagan@uiowa.edu; Jean-francois.moyen@univ-st-etienne.fr. Search for other works by this author on: GSW Google Scholar Tracy Rushmer; Rushmer Mark Reagan; Reagan 2Department Geoscience, University Iowa, Iowa City, 52242, USA Jean-Francois Moyen...
International Ocean Discovery Program (IODP) Expedition 352 recovered a high-fidelity record of volcanism related to subduction initiation in the Bonin fore-arc. Two sites (U1440 and U1441) located deep water nearer trench basalts rocks; two (U1439 U1442) shallower further from boninites rocks. Drilling both areas ended dolerites inferred be sheeted intrusive The apparently erupted immediately after have compositions similar those most depleted generated by rapid sea-floor spreading at...
Abstract Boninites are rare, high-Si, high-Mg, low-Ti lavas that have considerable tectonic significance, especially for recognizing and interpreting episodes of subduction initiation in the geologic record. Formal identification classification boninites may be carried out using MgO-SiO2 MgO-TiO2 diagrams to find compositions satisfy modified International Union Geological Sciences (IUGS) criteria Si8 > 52 Ti8 < 0.5, where refer concentrations oxides at 8 wt% MgO. However, screening...
High-precision uranium-thorium mass spectrometric chronology and (18)O-(13)C isotopic analysis of speleothem calcite from Cold Water Cave in northeast Iowa have been used to chart mid-Holocene climate change. Significant shifts dagger(18)O dagger(13)C values coincide with well-documented Holocene vegetation changes. Temperature estimates based on (18)O/(16)O ratios suggest that the warmed rapidly by about 3 degrees C at 5900 years before present then cooled 4 3600 present. Initiation a...
Turrialba volcano, the southeasternmost volcano in Central American arc, is constructed of medium to high‐K calcalkaline basalts, andesites, and dacites, plus rare basalts with unusually high Nb concentrations. The compositions these high‐Nb are more similar those intraplate than they typical or arc‐tholeiitic basalts. association arc front volcanoes, seemingly being restricted volcanoes that overlie Oligocene younger subducting crust edges plates. at have generally major element, trace...
The Sangiran dome is the primary stratigraphic window for Plio-Pleistocene deposits of Solo basin Central Jawa. has yielded nearly 80 Homo erectus fossils, around 50 which have known findspots. With a hornblende 40 Ar/ 39 Ar plateau age 1.66 ± 0.04 mega-annum (Ma) reportedly associated with two fossils [Swisher, C.C., III, Curtis, G. H., Jacob, T., Getty, A. G., Suprijo, & Widiasmoro (1994) Science 263, 1118–1121), offers evidence that early dispersed to East Asia during earliest...
Abstract The Izu‐Bonin‐Mariana (IBM) fore arc preserves igneous rock assemblages that formed during subduction initiation circa 52 Ma. International Ocean Discovery Program (IODP) Expedition 352 cored four sites in the near Ogasawara Plateau order to document magmatic response and physical, petrologic, chemical stratigraphy of a nascent zone. Two these (U1440 U1441) are underlain by fore‐arc basalt (FAB). FABs have mid‐ocean ridge (MORB)‐like compositions, however, FAB consistently lower...
Arc basalts have a higher proportion of Fe in an oxidized state (Fe^(3+)) relative to Fe^(2+) compared mid-oceanic ridge (MORBs), likely because slab-derived fluids oxidize the mantle wedge where subduction zone magmas originate. Yet, time scales over which oxygen fugacity changes during initiation and margin evolution are unknown. speciation ratios show that produced early stages Mariana arc record fugacities ∼2× more than MORB. Mantle rises by ∼1.3 orders magnitude as slab become involved...
Several varieties of seafloor hydrothermal vents with widely varying fluid compositions and temperatures vent communities occur in different tectonic settings. The discovery the Lost City field Mid-Atlantic Ridge has stimulated interest role serpentinization peridotite generating H 2 - CH 4 -rich fluids associated carbonate chimneys, as well biological supported highly reduced, alkaline environments. Abundant vesicomyid clam a serpentinite-hosted system southern Mariana forearc were...
Abstract Plate tectonics requires the formation of plate boundaries. Particularly important is enigmatic initiation subduction: sliding one below other, and primary driver tectonics. A continuous, in situ record subduction was recovered by International Ocean Discovery Program Expedition 352, which drilled a segment fore-arc Izu-Bonin-Mariana system, revealing distinct magmatic progression with rapid timescale (approximately 1 million years). Here, using numerical models, we demonstrate that...
Abstract International Ocean Discovery Program Expedition 352 to the Izu‐Bonin forearc cored over 800 m of basement comprising boninite and boninite‐series lavas. This is most extensive, well‐constrained suite series lavas ever obtained from in situ oceanic crust. The boninites are characterized as high‐silica (HSB), low‐silica (LSB), or basaltic based on their SiO 2 ‐MgO‐TiO relations. principal fractionation products all three high‐Mg andesites (HMA). Lavas recovered >250 meters below...
Oxygen‐isotope ratios of olivine and plagioclase phenocrysts in basalts basaltic andesites from the Central American arc vary systematically with location, a minimum δ 18 O value 4.6 (below range typical terrestrial basalts) Nicaragua near center to maximum 5.7 (above range) Guatemala northwest end arc. These oxygen‐isotope variations correlate major trace element abundances Sr Nd isotope compositions host lavas, defining trends that suggest reflect slab contributions mantle sources these...
Research Article| June 01, 1984 Geology and geochemistry of early arc-volcanic rocks from Guam MARK K. REAGAN; REAGAN 1Department Geosciences, University Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar AREND MEIJER GSA Bulletin (1984) 95 (6): 701–713. https://doi.org/10.1130/0016-7606(1984)95<701:GAGOEA>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Manager Share Icon Facebook Twitter LinkedIn MailTo Tools Get...
We report 238 U‐ 230 Th‐ 226 Ra‐ 210 Pb‐ Po, 232 228 Ra and 235 231 Pa measurements for a suite of 14 geologically geochemically well‐characterized basaltic samples from the Samoan volcanoes Vailulu'u, Malumalu, Savai'i. Maximum eruption ages based on presence parent‐daughter disequilibria indicate that Vailulu'u is magmatically productive with young lavas (<8 Ka) resurfacing both its summit crater lower flanks. Pb Po several flows have erupted within in past 100 years, newest observed...
Open-conduit basaltic volcanoes can be characterised by sudden large explosive events (paroxysms) that interrupt normal effusive and mild activity. In June-August 2019, one major explosion two paroxysms occurred at Stromboli volcano (Italy) within only 64 days. Here, via a multifaceted approach using clinopyroxene, we show arrival of mafic recharges up to few days before the onset these their effects on eruption pattern Stromboli, as prime example persistently active, open-conduit volcano....
The upper mantle is critical for our understanding of terrestrial magmatism, crust formation, and element cycling between Earth's solid interior, hydrosphere, atmosphere, biosphere. Mantle composition evolution have been primarily inferred by surface sampling indirect methods. We recovered a long (1268-meter) section serpentinized abyssal peridotite interleaved with thin gabbroic intrusions. find depleted compositions notable variations in mineralogy controlled melt flow. Dunite zones...
Tham Khuyen Cave (Lang Son Province, northern Vietnam) is one of the more significant sites to yield fossil vertebrates in east Asia. During mid-1960s, excavation a suite deposits produced important hominoid dental remains middle Pleistocene age. We undertake rigorous analyses these sediments understand fluvial dynamics cave infilling as they determine how skeletal elements accumulate within and other Asian sites. Uranium/thorium series analysis speleothems brackets chronology for breaching,...
Abstract Speleothems from a well-ventilated dolomitic cave in the Pokhara Valley, central Nepal, preserve mineralogic record of Indian summer monsoon variability over past 2300 yr. Annually deposited aragonite layers formed between and 1500 yr B.P., indicating reduced precipitation increased aridity, whereas alternating calcite/aragonite laminae after B.P. elevated humidity. Dense, optically clear calcite 450 ± 5 to 360 20 (1550 1640 A.D.) indicate less-evaporative environment suggest...