Physical Sciences and Mathematics Commons^™

Reflectance Spectroscopy Datasets For The Validation Of Tanager, Kristiana Lapo, Kathleen Hoza, Sammy Theuer, Melissa S. Rice

Geology Faculty Publications

The Three-Axis N-sample Automated Goniometer for Evaluating Reflectance (TANAGER) is a custom goniometer designed to rapidly acquire spectra of natural rock surfaces across the full scattering hemisphere. TANAGER interfaces with a Malvern Panalytical ASD Fieldspec 4 Hi-Res reflectance spectrometer to collect data from 350-2500 nm at a range of incidence, emission and azimuth angles. To validate the accuracy and repeatability of data collected with TANAGER - and to characterize any instrument noise, artifacts or sample heating effects - we collected spectra from three categories of targets: (1) powdered calcium sulfate (anhydrite), (2) naturally weathered basalt surfaces, and (3) color calibration …

Mastcam Multispectral Database From The Curiosity Rover’S Traverse In Gale Crater, Mars (Sols 0-2302), Melissa S. Rice

Geology Faculty Publications

The Mars Science Laboratory (MSL) Curiosity rover has explored fluvio-deltaic, lacustrine, and aeolian strata as it climbed over 400 m in elevation over the first 2302 sols of its traverse. Curiosity’s Mast Camera (Mastcam) instrument is a pair of multispectral imagers covering visible to near-infrared (VNIR) wavelengths (445 nm - 1013 nm). Mastcam spectra can broadly distinguish between iron phases and oxidation states, and in combination with chemical data from other instruments, Mastcam spectra can help constrain mineralogy, depositional origin, and diagenesis. This dataset includes representative Mastcam spectra from >600 multispectral observations acquired across Curiosity’s traverse through Vera Rubin ridge …

Google Earth Model Of The Southern Alisitos Arc Crustal Section, Baja California, Rebecca Morris, Sarah Medynski, Susan M. Debari, Cathy Busby

Geology Faculty Publications

The Cretaceous Alisitos Ocean Arc 3D Model version 1 (v1) is a publically accessible and interactive 3D arc crustal model, with geologic map overlays on Google Earth. The model provides a virtual field trip through the upper- to middle-crust transition in the exhumed 110 Ma southern Alisitos Arc, Baja California, Mexico. This region was chosen for the model as it exposes a structurally intact and minimally altered transition zone between heterogeneous volcanic upper crust through the underlying plutonic rocks (up to ~7 km deep). The model is organized into three paleo-volcanic centers, which include (from north to south): a northern …

Metamorphism Of The Sierra De Maz And Implications For The Tectonic Evolution Of The Mara Terrane, Andrew Tholt, Sean R. Mulcahy, William C. Mcclelland, Sarah M. Roeske, Vinícius T. Meira, Patricia Webber, Emily Houlihan, Matthew A. Coble, Jeffrey D. Vervoort

Geology Faculty Publications

The Mesoproterozoic MARA terrane of western South America is a composite igneous-metamorphic complex that is important for Paleozoic paleogeographic reconstructions and the relative positions of Laurentia and Gondwana. The magmatic and detrital records of the MARA terrane are consistent with a Laurentian origin; however, the metamorphic and deformation records lack sufficient detail to constrain the correlation of units within the MARA terrane and the timing and mechanisms of accretion to the Gondwana margin.

Combined regional mapping, metamorphic petrology, and garnet and monazite geochronology from the Sierra de Maz of northwest Argentina suggest that the region preserves four distinct litho-tectonic units …

Building Arc Crust: Plutonic To Volcanic Connections In An Extensional Oceanic Arc, The Southern Alisitos Arc, Baja California, Rebecca A. Morris, Susan M. Debari, Cathy Busby, Sarah Medynski, Brian R. Jicha

Geology Faculty Publications

The ~50 km long Rosario segment of the Cretaceous Alisitos oceanic arc terrane provides undeformed three-dimensional exposures of the upper 7 km of an oceanic extensional arc, where crustal generation processes are recorded in both the volcanic and underlying plutonic rocks. These exceptional exposures allow for the study of the physical and chemical links between the rock units and help constrain the differentiation processes active during the growth and evolution of arc crust. This study focuses on the southern third of the Rosario segment, previously referred to as the southern volcano-bounded basin, and its plutonic underpinnings. Upper crustal rocks in …

Subduction Initiation And Early Evolution Of The Easton Metamorphic Suite, Northwest Cascades, Washington, Jeremy L. Cordova, Sean R. Mulcahy, Elizabeth R. Schermer, Laura E. Webb

Geology Faculty Publications

The Easton metamorphic suite, in the northwest Cascades of Washington State, preserves an inverted metamorphic sequence with ultramafic rocks underlain by amphibolite and high-temperature blueschist juxtaposed above low-temperature blueschists. The sequence is interpreted as a metamorphic sole and younger accreted rocks that formed during and after the initiation of Farallon plate subduction beneath North America in Jurassic time. Two high-temperature deformation events are recorded in the metamorphic sole at ∼10 kbar and ∼760 °C to 590 °C between >167 and 164 Ma. High-temperature blueschist partly overprints the amphibolite but may have accreted separately at ∼530 °C between ca. 165 and …

Particle Size Specific Magnetic Properties Across The Norwegian‐Greenland Seas: Insights Into The Influence Of Sediment Source And Texture On Bulk Magnetic Records, Robert G. Hatfield, Benjamin H. Wheeler, Brendan T. Reilly, Joseph S. Stoner, Bernard A. Housen

Geology Faculty Publications

We make fundamental observations of the particle size variability of magnetic properties from 71 core tops that span the southern Greenland and Norwegian Seas. These data provide the first detailed regional characterization of how bulk magnetic properties vary with sediment texture, sediment source, and sediment transport. Magnetic susceptibility (MS) and hysteresis parameters were measured on the bulk sediment and the five constituent sediment particle size fractions (clay, fine silt, medium silt, coarse silt, and sand). The median MS value of the medium silt size fraction is ~3–5 times higher than that of the sand and clay size fractions and results …

Construction, Emplacement, And Geochemical Evolution Of Deep-Crustal Intrusions: Tenpeak And Dirtyface Plutons, North Cascades, Western North America, Robert B. Miller, Susan M. Debari, Scott R. Paterson

Geology Faculty Publications

Deep plutonic systems represent an important link between lower-crustal melt-generation sites and higher-level regions of magma accumulation, but models for these systems are limited by the relative scarcity of exposed weakly deformed, deep-crustal plutons. Exceptions include the ca. 92.3–89.7 Ma, dominantly tonalitic Tenpeak pluton and the smaller, nearby ca. 91 Ma Dirtyface pluton of the North Cascades (western North America), which represent deeply exposed crustal levels (∼25–35 km) of a Cordilleran arc. Initial subduction-driven magmatism in the Tenpeak pluton was marked by co-magmatic hydrous mafic and felsic magmas, which formed gabbro, diorite, tonalite, and hornblendite within a heterogeneous mafic complex. …

U-Pb And Hf Isotopic Evidence For An Arctic Origin Of Terranes In Northwestern Washington, Elizabeth R. Schermer, Eric A. Hoffnagle, Edwin H. Brown, George E. Gehrels, William C. Mcclelland

Geology Faculty Publications

New field, U-Pb, and Lu-Hf zircon data constrain the geologic history, age, and origin of the Yellow Aster Complex (YAC) in northwestern Washington, providing insight into the tectonic history of this and related Paleozoic arc terranes of the western North American Cordillera. Mapping shows that the oldest YAC rocks consist of quartzofeldspathic paragneiss (meta-arkose) and quartzose calc-silicate paragneiss (metacalcareous siltstone) in gradational contact. Paragneisses are cut by syn-tectonic and post-tectonic intrusions and faulted against granitic orthogneiss. U-Pb zircon results show that (1) maximum depositional ages of paragneisses are Silurian to Early Devonian (432– 390 Ma); (2) detrital zircons from quartzose …

Biogenic Weathering: Solubilization Of Iron From Minerals By Epilithic Freshwater Algae And Cyanobacteria, George E. Mustoe

Geology Faculty Publications

A sandstone outcrop exposed to freshwater seepage supports a diverse assemblage of photosynthetic microbes. Dominant taxa are two cyanophytes (Oscillatoria sp., Rivularia sp.) and a unicellular green alga (Palmellococcus sp.). Less abundant taxa include a filamentous green alga, Microspora, and the desmid Cosmarium. Biologic activity is evidenced by measured levels of chlorophyll and lipids. Bioassay methods confirm the ability of these microbes to dissolve and metabolize Fe from ferruginous minerals. Chromatographic analysis reveals citric acid as the likely chelating agent; this low molecular weight organic acid is detectable in interstitial fluid in the sandstone, measured as …

The Recent Volcanic History Of Axial Seamount: Geophysical Insights Into Past Eruption Dynamics With An Eye Toward Enhanced Observations Of Future Eruptions, William Wilcock, Robert Dziak, Maya Tolstoy, William Chadwick, Scott Nooner, Delwayne Bohnenstiel, Jacqueline Caplan-Auerbach, Felix Waldhauser, Adrien Amulf, Christian Ballard, Tai-Kwan Lau, Joseph Haxel, Yen Joe Tan, Charles Garcia, Samuel Levy, M. Everett Mann

Geology Faculty Publications

To understand the processes that form oceanic crust as well as the role of submarine volcanoes in exchanging heat and chemicals with the ocean and in supporting chemosynthetic biological communities, it is essential to study underwater eruptions. The world’s most advanced underwater volcano observatory—the Ocean Observatories Initiative Cabled Array at Axial Seamount—builds upon ~30 years of sustained geophysical monitoring at this site with autonomous and remote systems. In April 2015, only months after the Cabled Array’s installation, it recorded an eruption at Axial Seamount, adding to the records of two prior eruptions in 1998 and 2011. Between eruptions, magma recharge …

Early Onset Of Franciscan Subduction, Sean R. Mulcahy, Jesslyn K. Starnes, Howard W. Day, Matthew A. Coble, Jeffrey D. Vervoort

Geology Faculty Publications

The Franciscan subduction complex of California is considered a type example of a subduction-accretion system, yet the age of subduction initiation and relationship to the tectonic history of western North America remain controversial. Estimates for the timing of Franciscan subduction initiation are largely based either indirectly on regional tectonic arguments or from the ages of high-grade blocks within mélange. Many of the high-grade blocks record counterclockwise pressure-temperature paths with early amphibolite overprinted by later eclogite and blueschist; however, their origin and significance with respect to subduction initiation have been debated. In contrast, some high-grade blocks show evidence for clockwise pressure-temperature …

Paleomagnetism And Rotation History Of The Blue Mountains, Oregon, Usa, Bernard A. Housen

Geology Faculty Publications

An important element in reconstructions of the Cordilleran margin of North America includes longstanding debate regarding the timing and amount of rotation of the Blue Mountains in eastern Oregon, and the origin of geometric features such as the Columbia Embayment, which was a subject of some of Bill Dickinson’s early research. Suppositions of significant clockwise rotation of the Blue Mountains derived from Dickinson’s work were confirmed in the 1980s by paleomagnetic results from Late Jurassic–Early Cretaceous plutonic rocks, and secondary directions from Permian–Triassic units of the Wallowa–Seven Devils arc that indicate ~60° clockwise rotation of the Blue Mountains.

This study …

Phillipsite And Al-Tobermorite Mineral Cements Produced Through Low-Temperature Water-Rock Reactions In Roman Marine Concrete, Marie D. Jackson, Sean R. Mulcahy, Heng Chen, Yao Li, Qinfei Li, Piergiulio Cappelletti, Hans-Rudolf Wenk

Geology Faculty Publications

Pozzolanic reaction of volcanic ash with hydrated lime is thought to dominate the cementing fabric and durability of 2000-year-old Roman harbor concrete. Pliny the Elder, however, in first century CE emphasized rock-like cementitious processes involving volcanic ash (pulvis) “that as soon as it comes into contact with the waves of the sea and is submerged becomes a single stone mass (fierem unum lapidem), impregnable to the waves and every day stronger” (Naturalis Historia 35.166). Pozzolanic crystallization of Al-tobermorite, a rare, hydrothermal, calcium-silicate-hydrate mineral with cation exchange capabilities, has been previously recognized in relict lime clasts …

Explosive Processes During The 2015 Eruption Of Axial Seamount, As Recorded By Seafloor Hydrophones, Jacqueline Caplan-Auerbach, R. P. Dziak, J. Haxel, D. R. Bohnenstiehl, C. Garcia

Geology Faculty Publications

Following the installation of the Ocean Observatories Initiative cabled array, the 2015 eruption of Axial Seamount, Juan de Fuca ridge, became the first submarine eruption to be captured in real time by seafloor seismic and acoustic instruments. This eruption also marked the first instance where the entire eruption cycle of a submarine volcano, from the previous eruption in 2011 to the end of the month-long 2015 event, was monitored continuously using autonomous ocean bottom hydrophones. Impulsive sounds associated with explosive lava-water interactions are identified within hydrophone records during both eruptions. Explosions within the caldera are acoustically distinguishable from those occurring …

Phillipsite And Al-Tobermorite Mineral Cements Produced Through Low-Temperature Water-Rock Reactions In Roman Marine Concrete, Sean R. Mulcahy, Marie D. Jackson, Heng Chen, Yao Li, Piergiulio Cappelletti, Hans-Rudolf Wenk

Geology Faculty Publications

Pozzolanic reaction of volcanic ash with hydrated lime is thought to dominate the cementing fabric and durability of 2000-year-old Roman harbor concrete. Pliny the Elder, however, in first century CE emphasized rock-like cementitious processes involving volcanic ash (pulvis) “that as soon as it comes into contact with the waves of the sea and is submerged becomes a single stone mass (fierem unum lapidem), impregnable to the waves and every day stronger” (Naturalis Historia 35.166). Pozzolanic crystallization of Al-tobermorite, a rare, hydrothermal, calcium-silicate-hydrate mineral with cation exchange capabilities, has been previously recognized in relict lime clasts of the concrete. Synchrotron-based X-ray …

A Pulsed-Air Model Of Blue Whale B Call Vocalizations, R. P. Dziak, J. H. Haxel, T-K. Lau, S. Heimlich, Jacqueline Caplan-Auerbach, D. K. Mellinger, H. Matsumoto, B. Mate

Geology Faculty Publications

Blue whale sound production has been thought to occur by Helmholtz resonance via air flowing from the lungs into the upper respiratory spaces. This implies that the frequency of blue whale vocalizations might be directly proportional to the size of their sound-producing organs. Here we present a sound production mechanism where the fundamental and overtone frequencies of blue whale B calls can be well modeled using a series of short-duration (<1 >s) wavelets. We propose that the likely source of these wavelets are pneumatic pulses caused by opening and closing of respiratory valves during air recirculation between the lungs and …

Surface Slip During Large Owens Valley Fault Earthquakes, Elizabeth K. Haddon, Colin B. Amos, O. Zielke, A. S. Jayko, R. Bürgmann

Geology Faculty Publications

The 1872 Owens Valley earthquake is the third largest known historical earthquake in California. Relatively sparse field data and a complex rupture trace, however, inhibited attempts to fully resolve the slip distribution and reconcile the total moment release. We present a new, comprehensive record of surface slip based on lidar and field investigation, documenting 162 new measurements of laterally and vertically displaced landforms for 1872 and prehistoric Owens Valley earthquakes. Our lidar analysis uses a newly developed analytical tool to measure fault slip based on cross‐correlation of sublinear topographic features and to produce a uniquely shaped probability density function (PDF) …

Structural And Antiferromagnetic Properties Of Ba(Fe1−X−Ycoxrhy)2as2 Compounds, M. G. Kim, T. W. Heitmann, Sean R. Mulcahy, E. D. Bourret-Courchesne, R. J. Birgeneau

Geology Faculty Publications

We present a systematic investigation of the electrical, structural, and antiferromagnetic properties for the series of Ba(Fe_{1 −x−y}Co_xRh_y)₂As₂ compounds with fixed x ≈ 0.027 and 0 ≤ y ≤ 0.035. We compare our results for the Co-Rh doped Ba(Fe_1−x−yCo_xRh_y)₂As₂ compounds with the Co doped Ba(Fe_1−xCo_x)₂As₂ compounds. We demonstrate that the electrical, structural, antiferromagnetic, and superconducting properties of the Co-Rh doped compounds are similar to the properties of the Co doped compounds. We find that the …

Unblocking Temperatures Of Viscous Remanent Magnetism In Displaced Granitic Boulders, Icicle Creek Glacial Moraines (Washington, Usa), Juliet G. Crider, Danika M. Globokar, Russ F. Burmester, Bernard A. Housen

Geology Faculty Publications

Viscous remanent magnetization (VRM) may partially overprint original magnetization in rocks displaced by geomorphic events. An established theoretical relationship between the time and temperature of acquisition of VRM and the time and temperature of demagnetization suggests that laboratory demagnetization (unblocking) of VRM can be used to estimate the displacement age of rocks. We test this hypothesis at four nested glacial moraines in the Icicle Creek drainage of central Washington, the ages of which were previously determined by cosmogenic surface exposure dating. The moraines are composed primarily of granodiorite boulders, and magnetic remanence is carried dominantly by magnetite. Both the maximum …

Expedition 350 Methods, Y. Tamura, C. J. Busby, P. Blum, G. Guèrin, G. D.M. Andrews, A. K. Barker, J. L. R. Berger, E. M. Bongiolo, M. Bordiga, Susan M. Debari, J. B. Gill, C. Hamelin, J. Jia, E. H. John, A. -S. Jonas, M. Jutzeler, M. A.C. Kars, Z. A. Kita, K. Konrad, S. H. Mahoney, M. Martini, T. Miyazaki, R. J. Musgrave, D. B. Nascimento, A. R.L. Nichols, J. M. Ribeiro, T. Sato, J. C. Schindlbeck, A. K. Schmitt, S. M. Straub, M. J. Vautravers, Y. Yang

Geology Faculty Publications

This chapter of the International Ocean Discovery Program (IODP) Expedition 350 Proceedings volume documents the procedures and tools employed in the various shipboard laboratories of the R/V JOIDES Resolution during Expedition 350. This information applies only to shipboard work described in the Expedition Reports section of this volume. Methods for shore-based analyses of Expedition 350 samples and data will be described in the individual scientific contributions to be published in the open literature or in the Expedition Research Results section of this volume.

This section describes procedures and equipment used for drilling, coring, and hole completion; core handling; computation of …

Expedition 350 Summary, Y. Tamura, C. J. Busby, P. Blum, G. Guèrin, G. D.M. Andrews, A. K. Barker, J. L.R. Berger, E. M. Bongiolo, M. Bordiga, Susan M. Debari, J. B. Gill, C. Hamelin, J. Jia, E. H. John, A.-S. Jonas, J. Jutzeler, M A.C. Kars, Z. A. Kita, K. Konrad, S. H. Mahony, M. Martini, T. Myiazaki, R. J. Musgrave, D. B. Nascimento, A. R.L. Nichols, J. M. Ribeiro, T. Sato, J. C. Schindlbeck, A. K. Schmitt, S. M. Straub, M. J. Vautravers, Y. Yang

Geology Faculty Publications

International Ocean Discovery Program (IODP) Hole U1436A (proposed Site IBM-4GT) lies in the western part of the Izu fore-arc basin, ~60 km east of the arc-front volcano Aogashima, ~170 km west of the axis of the Izu-Bonin Trench, and 1.5 km west of Ocean Drilling Program (ODP) Site 792, at 1776 meters below sea level (mbsl). It was drilled as a 150 m deep geotechnical test hole for potential future deep drilling (5500 meters below seafloor [mbsf]) at proposed Site IBM-4 using the D/V Chikyu. Core from Site U1436 yielded a rich record of Late Pleistocene explosive volcanism, including …

Multi-Episodic Remagnetization Related To Deformation In The Pyrenean Internal Sierras, Esther Izquierdo-Llavall, Antonio Casas Sainz, Belén Oliva-Urcia, Russ F. Burmester, Emilio L. Pueyo, Bernard A. Housen

Geology Faculty Publications

The Internal Sierras (IS) in the southern margin of the Western and Central Axial Zone (Southern Pyrenees) are affected by a syn-orogenic remagnetization that provides information to reconstruct deformation geometries at the time of acquisition of magnetization. Furthermore, the IS structure changes strike along its structural trend, from ∼N120 to 130°E in the western and eastern margins to ∼N070–090°E in the central part. Palaeomagnetic techniques have been used to (i) accurately define the timing of remagnetization with regard to deformation and (ii) determine if the along-strike trend variation in the IS was induced by deformation and thrust emplacement during the …

Long-Term Explosive Degassing, Debris Flows And Volatile Release At West Mata Submarine Volcano, R. P. Dziak, D. R. Bohnenstiehl, E. T. Baker, H. Matsumoto, Jacqueline Caplan-Auerbach, R. W. Embley, S. L. Walker, T. -K. Lau, W. W. Chadwick Jr.

Geology Faculty Publications

West Mata is a 1200 m deep submarine volcano where explosive boninite eruptions were observed in 2009. The acoustic signatures from the volcano’s summit eruptive vents Hades and Prometheus were recorded with an in situ (~25m range) hydrophone during ROV dives in May 2009 and with local (~5km range) moored hydrophones between December 2009 and August 2011. The sensors recorded low frequency (1–40 Hz), short duration explosions consistent with magma bubble bursts from Hades,and broadband, 1–5 min duration signals associated with episodes of fragmentation degassing from Prometheus. Long-term eruptive degassing signals, recorded through May 2010, preceded a several …

Holocene Earthquakes And Right-Lateral Slip On The Left-Lateral Darrington-Devils Mountain Fault Zone, Northern Puget Sound, Washington, Stephen F. Personius, Richard W. Briggs, Alan R. Nelson, Elizabeth R. Schermer, J. Zebulon Maharrey, Brian L. Sherrod, Sarah A. Spaulding, Lee-Ann Bradley

Geology Faculty Publications

Sources of seismic hazard in the Puget Sound region of northwestern Washington include deep earthquakes associated with the Cascadia subduction zone, and shallow earthquakes associated with some of the numerous crustal (upper-plate) faults that crisscross the region. Our paleoseismic investigations on one of the more prominent crustal faults, the Darrington–Devils Mountain fault zone, included trenching of fault scarps developed on latest Pleistocene glacial sediments and analysis of cores from an adjacent wetland near Lake Creek, 14 km southeast of Mount Vernon, Washington. Trench excavations revealed evidence of a single earthquake, radiocarbon dated to ca. 2 ka, but extensive burrowing and …

Hydroacoustic Investigations Of Submarine Landslides At West Mata Volcano, Lau Basin, Jacqueline Caplan-Auerbach, R. P. Dziak, D. R. Bohnenstiehl, W. W. Chadwick, T. -K. Lau

Geology Faculty Publications

Submarine landslides are an important process in volcano growth yet are rarely observed and poorly understood. We show that landslides occur frequently in association with the eruption of West Mata volcano in the NE Lau Basin. These events are identifiable in hydroacoustic data recorded between ~5 and 20 km from the volcano and may be recognized in spectrograms by the weak and strong powers at specific frequencies generated by multipathing of sound waves. The summation of direct and surface-reflected arrivals causes interference patterns in the spectrum that change with time as the landslide propagates. Observed frequencies are consistent with propagation …

Crustal Shortening, Exhumation, And Strain Localization In A Collisonal Orogen: The Bajo Pequeno Shear Zone, Sierra De Pie De Palo, Argentina, Joshua M. Garber, Sarah M. Roeske, Jessica Warren, Sean R. Mulcahy, William C. Mcclelland, Lauren J. Austin, Paul R. Renne, Graciela I. Vujovich

Geology Faculty Publications

The Bajo Pequeño Shear Zone (BPSZ) is a lower-crustal shear zone that records shortening and exhumation associated with the establishment of a new plate boundary, and its placement in a regional structural context suggests that local- to regional-scale strain localization occurred with progressive deformation. A kilometer-scale field and analytical cross section through the ~80 m thick BPSZ and its adjacent rocks indicates an early Devonian (405–400 Ma) phase of deformation on the western margin of Gondwanan continental crust. The earliest stages of the BPSZ, recorded by metamorphic and microstructural data, involved thrusting of a hotter orthogneiss over a relatively cool …

Multiple Migmatite Events And Cooling From Granulite Facies Metamorphism Within The Famatina Arc Margin Of Northwest Argentina, Sean R. Mulcahy, Sarah M. Roeske, William C. Mcclelland, Joshua R. Ellis, Fred Jourdan, Paul R. Renne, Jeffrey D. Vervoort, Graciela I. Vujovich

Geology Faculty Publications

The Famatina margin records an orogenic cycle of convergence, metamorphism, magmatism, and extension related to the accretion of the allochthonous Precordillera terrane. New structural, petrologic, and geochronologic data from the Loma de Las Chacras region demonstrate two distinct episodes of lower crustal migmatization. The first event preserves a counterclockwise pressure-temperature path in kyanite-K-feldspar pelitic migmatites that resulted in lower crustal migmatization via muscovite dehydration melting at ∼12 kbar and 868°C at 461 ±1.7 Ma. The shape of the pressure temperature path and timing of metamorphism are similar to those of regional midcrustal granulites and suggest pervasive Ordovician migmatization throughout the …

Izu-Bonin-Mariana Rear Arc: The Missing Half Of The Subduction Factory, Yoshihiko Tamura, Abigail K. Barker, Cathy J. Busby, Julien L.R. Berger, Peter Blum, Everton M. Bongiolo, Gilles Guèrin, Manuela Bordiga, Graham D.M. Andrews, Susan M. Debari, James B. Gill, Cedric Hamelin, Jihui Jia, Eleanor H. John, Ann-Sophie Jonas, Martin Jutzeler, Myriam A.C. Kars, Zachary A. Kita, Kevin Konrad, Susan H. Mahony, Michelangelo Martini, Takashi Miyazaki, Robert J. Musgrave, Debora B. Nascimento, Alexander R.L. Nichols, Julia M. Ribeiro, Tomoki Sato, Julie C. Schindlbeck, Axel K. Schmitt, Susanne M. Straub, Maryline J. Vautravers, Yang Yang

Geology Faculty Publications

4GT) lies in the western part of the Izu fore-arc basin, ~60 km east of the arc-front volcano Aogashima, ~170 km west of the axis of the Izu-Bonin Trench, 1.5 km west of Ocean Drilling Program (ODP) Site 792, and at 1776 meters below sea level (mbsl). It was drilled as a 150 m deep geotechnical test hole for potential future deep drilling (5500 meters below seafloor [mbsf]) at proposed Site IBM-4 using the D/V Chikyu. Core from Site U1436 yielded a rich record of Late Pleistocene explosive volcanism, including distinctive black glassy mafic ash layers that may record large-volume …

Melt Inclusion Evidence For Magma Evolution At Mutnovsky Volcano, Kamchatka, K. Robertson, A. Simon, T. Pettke, Sean R. Mulcahy, E. Smith, O. Selyangin, A. Kiryukhin, J. D. Walker

Geology Faculty Publications

Mutnovsky Volcano, located in Kamchatka, Russia, is a young volcano that has formed a series of four overlapping stratocones over its approximately 80 ka history. Erupted products at Mutnovsky range in composition from basalts to dacites; basalts are the most common. In this study, melt inclusions from representative samples of all erupted compositions from all four eruptive centers were analyzed to investigate the causes of the compositional heterogeneity, melt evolution, and pre-eruptive magma dynamics. Melt inclusions from Mutnovsky were sampled in olivine, plagioclase, orthopyroxene, and clinopyroxene. The melt inclusion data represent a wide range of melt compositions, from basalt through …