Adam J.R. Kent

article

Spatial and temporal variability in Marquesas Islands volcanism revealed by 3He/4He and the composition of olivine-hosted melt inclusions

Kevin Konrad, David W. Graham, Adam J.R. Kent, Anthony A.P. Koppers

Chemical Geology > 2018 > 477 > C > 161-176

The Marquesas Islands are a volcanic chain having an oblique orientation to Pacific plate motion. They represent the surface manifestation of a mantle hotspot having a low melt flux and a large intrinsic chemical and isotopic heterogeneity. Here we provide new helium isotope data for olivine separated from 23 basalts and one gabbroic xenolith, plus whole rock major and trace element data for the same...

article

The analytical limits of modeling short diffusion timescales

Richard W. Bradshaw, Adam J.R. Kent

Chemical Geology > 2017 > 466 > C > 667-677

Diffusion modeling of chemical zonation in crystals and glasses is a widely used method of quantifying the timescales of a variety of geological processes. Obtaining timescale information from diffusion modeling relies on fitting modeled diffusion profiles to measured compositional gradients. Thus analytical factors, such as spatial resolution, analysis location and analytical uncertainty have the...

article

Frequency and volumes of ignimbrite eruptions following the Late Neogene initiation of the Central Oregon High Cascades

Bradley W. Pitcher, Adam J.R. Kent, Anita L. Grunder, Robert A. Duncan

Journal of Volcanology and Geothermal Research > 2017 > 339 > C > 1-22

The late Neogene Deschutes Formation of central Oregon preserves a remarkable volcanic and sedimentary record of the initial stages of High Cascades activity following an eastward shift in the locus of volcanism at ~7.5Ma. Numerous ignimbrite and tephra-fall units are contained within the formation, and since equivalent deposits are relatively rare for the Quaternary Cascades, the eruptions of the...

article

Magma transport and olivine crystallization depths in Kīlauea’s east rift zone inferred from experimentally rehomogenized melt inclusions

Robin M. Tuohy, Paul J. Wallace, Matthew W. Loewen, Donald A. Swanson, more

Geochimica et Cosmochimica Acta > 2016 > 185 > C > 232-250

Concentrations of H₂O and CO₂ in olivine-hosted melt inclusions can be used to estimate crystallization depths for the olivine host. However, the original dissolved CO₂ concentration of melt inclusions at the time of trapping can be difficult to measure directly because in many cases substantial CO₂ is transferred to shrinkage bubbles that form during post-entrapment cooling and crystallization. To...

article

Asthenosphere–lithosphere interactions in Western Saudi Arabia: Inferences from 3He/4He in xenoliths and lava flows from Harrat Hutaymah

Kevin Konrad, David W. Graham, Carl R. Thornber, Robert A. Duncan, more

Lithos > 2016 > 248-251 > C > 339-352

Extensive volcanic fields on the western Arabian Plate have erupted intermittently over the last 30Ma following emplacement of the Afar flood basalts in Ethiopia. In an effort to better understand the origin of this volcanism in western Saudi Arabia, we analyzed ³He/⁴He, and He, CO₂ and trace element concentrations in minerals separated from xenoliths and lava flows from Harrat Hutaymah, supplemented...

article

Timing and composition of continental volcanism at Harrat Hutaymah, western Saudi Arabia

Robert A. Duncan, Adam J.R. Kent, Carl R. Thornber, Tyler D. Schlieder, more

Journal of Volcanology and Geothermal Research > 2016 > 313 > C > 1-14

Harrat Hutaymah is an alkali basalt volcanic field in north-central Saudi Arabia, at the eastern margin of a large Neogene continental, intraplate magmatic province. Lava flow, tephra and spatter cone compositions in the field include alkali olivine basalts and basanites. These compositions contrast with the predominantly tholeiitic, fissure-fed basalts found along the eastern margin of the Red Sea...

article

Deep-sea ash layers reveal evidence for large, late Pleistocene and Holocene explosive activity from Sumatra, Indonesia

Morgan J. Salisbury, Jason R. Patton, Adam J.R. Kent, Chris Goldfinger, more

Journal of Volcanology and Geothermal Research > 2012 > 231-232 > Complete > 61-71

Deep-sea tephra layers sampled from sediment cores collected within, and adjacent to the Sunda trench of offshore Sumatra reveal evidence for five previously undocumented, and apparently large (minimum volume >0.6–>6.3km ³ ; volcanic explosivity index values of 4–5) explosive eruptions over the last ~31,000years, with a presumptive source of mainland Sumatra. Chemical analysis of glass...

article

Controls on long-term low explosivity at andesitic arc volcanoes: Insights from Mount Hood, Oregon

Alison M. Koleszar, Adam J.R. Kent, Paul J. Wallace, William E. Scott

Journal of Volcanology and Geothermal Research > 2012 > 219-220 > Complete > 1-14

The factors that control the explosivity of silicic volcanoes are critical for hazard assessment, but are often poorly constrained for specific volcanic systems. Mount Hood, Oregon, is a somewhat atypical arc volcano in that it is characterized by a lack of large explosive eruptions over the entire lifetime of the current edifice (~500,000years). Erupted Mount Hood lavas are also compositionally homogeneous,...

article

Constraints on crystal storage timescales in mixed magmas: Uranium-series disequilibria in plagioclase from Holocene magmas at Mount Hood, Oregon

Gary R. Eppich, Kari M. Cooper, Adam J.R. Kent, Alison Koleszar

Earth and Planetary Science Letters > 2012 > 317-318 > Complete > 319-330

Uranium-series crystal ages, interpreted within a textural and geochemical framework, can provide insight into crystal storage timescales, especially in cases where crystals may derive from multiple sources. We report here ²³⁰ Th– ²²⁶ Ra model ages of two distinct populations of plagioclase from low silica dacites from Mount Hood, Oregon, a volcano where previous studies show that...

article

Gas transport model for the magmatic system at Mount Pinatubo, Philippines: Insights from (210Pb)/(226Ra)

Theresa M. Kayzar, Kari M. Cooper, Mark K. Reagan, Adam J.R. Kent

Journal of Volcanology and Geothermal Research > 2009 > 181 > 1-2 > 124-140

Measurements of ²²⁶ Ra– ²¹⁰ Pb disequilibria in eruptive products have the potential to track the accumulation or loss of volatiles in magmatic systems on timescales of decades because the intermediate nuclide, ²²² Rn, follows the gas phase. We present measurements of ²¹⁰ Pb– ²²⁶ Ra disequilibria for whole-rock samples representing a time sequence of tephra...

article

Pb isotope variations in hydrogenetic Fe–Mn crusts from the Izu–Bonin fore-arc

David W. Peate, Lee Falkena, Adam J.R. Kent

Chemical Geology > 2009 > 258 > 3-4 > 288-298

Fe–Mn crusts were recovered from the western escarpment of the Bonin Ridge in the Izu–Bonin fore-arc region (dive site #824: 28.612°N, 141.803°E) at water depths of c. 2900 m using the Shinkai 6500 submersible during cruise YK 04–05. Major and trace element data and XRD mineralogy indicate that the crusts are hydrogenetic in origin. We present profiles of variations in Pb isotope composition measured...

article

Magmatic volatile contents and degassing-induced crystallization at Volcán Jorullo, Mexico: Implications for melt evolution and the plumbing systems of monogenetic volcanoes

Emily R. Johnson, Paul J. Wallace, Katharine V. Cashman, Hugo Delgado Granados, more

Earth and Planetary Science Letters > 2008 > 269 > 3-4 > 478-487

Monogenetic basaltic cinder cones are abundant on Earth and exhibit a wide range of eruptive styles, including violent explosions. However, the mechanisms driving explosive cinder cone eruptions are still poorly understood. Here we investigate relations between volatiles, degassing, and crystallization in a long-lived, historical, cinder cone eruption to better understand the plumbing systems of monogenetic...

article

Extreme geochemical heterogeneity in Afro-Arabian Oligocene tephras: Preserving fractional crystallization and mafic recharge processes in silicic magma chambers

Ingrid Ukstins Peate, Adam J.R. Kent, Joel A. Baker, Martin A. Menzies

LITHOS > 2008 > 102 > 1-2 > 260-278

Four Indian Ocean deep-sea tephras can be correlated to individual Oligocene on-land silicic pyroclastic units found in the Afro-Arabian flood volcanic province (Yemen and Ethiopia), providing valuable stratigraphic marker horizons. They also preserve among the largest geochemical heterogeneities observed in individual eruption events (SiO ₂ : 43 to 75 wt.% and 56 to 79 wt.%). The major, trace...

article

Determination of sulfur speciation and oxidation state of olivine hosted melt inclusions

Michael C. Rowe, Adam J.R. Kent, Roger L. Nielsen

Chemical Geology > 2007 > 236 > 3-4 > 303-322

In order to better understand what controls sulfur speciation in melt inclusions, and how that pertains to the original basalt composition, we have conducted a series of heating experiments on naturally quenched and crystalline olivine-hosted melt inclusions. Sulfur speciation was determined from S Kα peak shift measurements by electron microprobe on the experimentally heated inclusions as well as...

article

An overview of modern trends in petrography: Textural and microanalysis of igneous rocks

Dougal A. Jerram, Adam J.R. Kent

Journal of Volcanology and Geothermal Research > 2006 > 154 > 1-2 > vii-ix

article

Correlation of Indian Ocean tephra to individual Oligocene silicic eruptions from Afro-Arabian flood volcanism

Ingrid Ukstins Peate, Joel A. Baker, Adam J.R. Kent, Mohamed Al-Kadasi, more

Earth and Planetary Science Letters > 2003 > 211 > 3-4 > 311-327

Widespread silicic pyroclastic eruptions of the Oligocene Afro-Arabian flood volcanic province (ignimbrites and airfall tuffs) produced up to 20% of the total flood volcanic stratigraphy (>6x10 ⁴ km ³ ). Volumes of individual ignimbrites and tuffs exposed on land range from ~150 to >2000 km ³ and eight major units (15-100 m thick) were erupted in <2 Myr, placing these...

article

Contamination and melt aggregation processes in continental flood basalts: constraints from melt inclusions in Oligocene basalts from Yemen

Adam J.R. Kent, Joel A. Baker, Michael Wiedenbeck

Earth and Planetary Science Letters > 2002 > 202 > 3-4 > 577-594

Melt inclusions from Oligocene continental flood basalts (CFB) erupted in Yemen provide unique insight into the timing and nature of the processes that lead to crustal contamination and melt aggregation in CFB magmas. Large variations in trace element indices that are sensitive to the degree and composition of assimilated crustal material (e.g. K₂O=0.20–1.94 wt%, Ba=13–543 ppm, K/Nb=128–1603, Ba/Th=9–303)...

article

Chlorine in submarine glasses from the Lau Basin: seawater contamination and constraints on the composition of slab-derived fluids

Adam J.R. Kent, David W. Peate, Sally Newman, Edward M. Stolper, more

Earth and Planetary Science Letters > 2002 > 202 > 2 > 361-377

Measurements of chlorine concentrations in matrix glasses from 18 primitive (>6 wt% MgO) and eight evolved lavas from active spreading centers in the Lau Basin back-arc system provide insight into the processes which control chlorine concentrations in subduction-related magmas, and can be used to investigate chlorine enrichment related to fluids derived from the underlying subducted slab. Chlorine...

article

Melt inclusions at the millennium: toward a deeper understanding of magmatic processes

Erik H. Hauri, Adam J.R. Kent, Nicholas Arndt

Chemical Geology > 2002 > 183 > 1-4 > 1-3

article

Melt inclusions from Marianas arc lavas: implications for the composition and formation of island arc magmas

Adam J.R. Kent, Tim R. Elliott

Chemical Geology > 2002 > 183 > 1-4 > 263-286

We have measured the major and trace element compositions of a suite of olivine-hosted melt inclusions in basaltic lavas from the islands of Agrigan and Guguan (one sample each) from the Mariana arc, part of the larger Izu-Bonin-Mariana system. The two lava samples examined show distinctly different chemical signatures that are considered to represent the dominance of sediment melt (Agrigan) or fluid...

INFONA - science communication portal

Search results for: Adam J.R. Kent

Spatial and temporal variability in Marquesas Islands volcanism revealed by 3He/4He and the composition of olivine-hosted melt inclusions

The analytical limits of modeling short diffusion timescales

Frequency and volumes of ignimbrite eruptions following the Late Neogene initiation of the Central Oregon High Cascades

Magma transport and olivine crystallization depths in Kīlauea’s east rift zone inferred from experimentally rehomogenized melt inclusions

Asthenosphere–lithosphere interactions in Western Saudi Arabia: Inferences from 3He/4He in xenoliths and lava flows from Harrat Hutaymah

Timing and composition of continental volcanism at Harrat Hutaymah, western Saudi Arabia

Deep-sea ash layers reveal evidence for large, late Pleistocene and Holocene explosive activity from Sumatra, Indonesia

Controls on long-term low explosivity at andesitic arc volcanoes: Insights from Mount Hood, Oregon

Constraints on crystal storage timescales in mixed magmas: Uranium-series disequilibria in plagioclase from Holocene magmas at Mount Hood, Oregon

Gas transport model for the magmatic system at Mount Pinatubo, Philippines: Insights from (210Pb)/(226Ra)

Pb isotope variations in hydrogenetic Fe–Mn crusts from the Izu–Bonin fore-arc

Magmatic volatile contents and degassing-induced crystallization at Volcán Jorullo, Mexico: Implications for melt evolution and the plumbing systems of monogenetic volcanoes

Extreme geochemical heterogeneity in Afro-Arabian Oligocene tephras: Preserving fractional crystallization and mafic recharge processes in silicic magma chambers

Determination of sulfur speciation and oxidation state of olivine hosted melt inclusions

An overview of modern trends in petrography: Textural and microanalysis of igneous rocks

Correlation of Indian Ocean tephra to individual Oligocene silicic eruptions from Afro-Arabian flood volcanism

Contamination and melt aggregation processes in continental flood basalts: constraints from melt inclusions in Oligocene basalts from Yemen

Chlorine in submarine glasses from the Lau Basin: seawater contamination and constraints on the composition of slab-derived fluids

Melt inclusions at the millennium: toward a deeper understanding of magmatic processes

Melt inclusions from Marianas arc lavas: implications for the composition and formation of island arc magmas

Filter options

Publication date

Keywords

Journal

INFONA - science communication portal

Search results for: Adam J.R. Kent

Add recipient

Sending message cancelled

Are you sure you want to cancel sending this message?

Send message

Filter options

Publication date

Date range setting

Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.

Keywords

Journal

Reporting an error / abuse

Sending the report failed

Accessibility options