Article
Geosciences, Multidisciplinary
Katie Preece, Jenni Barclay, Richard J. Brown, Katy J. Chamberlain, Darren F. Mark
Summary: Research on Ascension Island has shown that over the past 1 million years, there have been more than 80 felsic pyroclastic eruptions, highlighting the uneven distribution of explosive events in both time and space. By dividing the island's volcanic activity into four periods, it reveals the cyclical nature of ocean island volcanism with predominantly mafic and felsic eruptions alternating.
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
(2021)
Article
Geochemistry & Geophysics
Benjamin E. Cohen, Darren F. Mark, William S. Cassata, Lara M. Kalnins, Martin R. Lee, Caroline L. Smith, David L. Shuster
Summary: Research found that the shergottites have a wide range of ages, with statistically robust Ar-40/Ar-39 isochron ages ranging from 161+/-9 Ma to 540+/-63 Ma, consistent with other dating methods. These data indicate that, despite experiencing shock metamorphism, the shergottites were sourced from the youngest volcanoes on Mars.
EARTH AND PLANETARY SCIENCE LETTERS
(2023)
Article
Multidisciplinary Sciences
Jennifer E. Thines, Ingrid A. Ukstins, Corey Wall, Mark Schmitz
Summary: The silicic volcanism in the Afro-Arabian large igneous province has produced some of the largest volcanic eruptions on Earth, occurring within a short timeframe but not causing major global environmental changes. High-precision dating shows the highest known long-term volumetric extrusive rate of silicic volcanism on Earth, providing valuable insights into the tempo of large-volume magma generation and eruption.
NATURE COMMUNICATIONS
(2021)
Article
Geosciences, Multidisciplinary
B. Eid, F. Lhuillier, S. A. Gilder, J. A. Pfaender, E. F. Gebru, D. Assbichler
Summary: The research findings from investigating the eruption history of the Ethiopia-Yemen Traps revealed that the local extrusion rate of the Afar plume head exceeded the average rate of the entire plume. The high titanium concentrations in the basalts suggest a faster local extrusion rate near the Afar plume axis.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Geochemistry & Geophysics
Allan Silva Gomes, Paulo Marcos Vasconcelos, Isabela de Oliveira Carmo
Summary: The presence of secondary phases in volcanic rocks and intrusive units may pose challenges for high resolution 40Ar/39Ar geochronology. Acid treatment is used to remove alteration products, but it has minimal impact on the accuracy of age determinations. Effective separation of atmospheric and radiogenic gases can successfully mitigate deleterious effects associated with alteration phases.
Article
Geochemistry & Geophysics
C. Antoine, R. A. Spikings, D. Miletic, J. S. Marsh, S. P. Gaynor, U. Schaltegger
Summary: The extrusive component of the Karoo Large Igneous Province, the Drakensberg Continental Flood basalts of South Africa and Lesotho, is mainly composed of altered tholeiitic basalts without suitable uraniferous mineral phases for high-precision dating. Multiple techniques were used to study the plagioclase in the lavas, revealing two distinct generations of plagioclase and different alteration phases. The study explains the inaccuracies in previous dating results and provides the most accurate age for the entire lava stack.
Article
Geochemistry & Geophysics
Edgar A. Cortes-Calderon, Ben S. Ellis, Chris Harris, Darren F. Mark, Julia Neukampf, John A. Wolff, Peter Ulmer, Olivier Bachmann
Summary: Through the study of the Fataga Group on Gran Canaria, it is found that it is a new location of low-delta O-18 felsic rocks, and the main magmatic process is fractional crystallization at shallow depths. The volcanic caldera and fault system also play a role in the assimilation of hydrothermally altered rocks.
JOURNAL OF PETROLOGY
(2022)
Article
Geology
Timothy Paulsen, John Encarnacion, Anne M. Grunow, Victor A. Valencia, Mark E. Pecha, Jeffrey Benowitz, Paul Layer
Summary: New age data from the Queen Maud Mountains in the Ross orogenic belt of Antarctica reveal that plutonism primarily occurred during the Cambrian to Ordovician periods, with polymodal age distributions consistent with regional magmatic flare-ups along the Pacific-Gondwana margin. Deformed plutons indicate deformation during the Cambrian to Ordovician periods, transitioning to post-tectonic magmatism and cooling at around 509-470 Ma. This suggests that the Queen Maud-Horlick Mountains share a similar petrotectonic history with other regions along the Pacific-Gondwana margin, providing new evidence for their tectonic evolution.
INTERNATIONAL GEOLOGY REVIEW
(2021)
Article
Geochemistry & Geophysics
P. W. Ball, G. G. Roberts, D. F. Mark, D. N. Barfod, N. J. White, B. H. Lodhia, M. M. Nahdi, S. Garni
Summary: Harrat Rahat is the largest volcanic field in Saudi Arabia and has been active from around 10 Ma to the present day. Recent eruptions at Harrat Rahat have been extensively studied, but the evolution of its oldest lava flows, known as the Shawahit Basalt, is poorly understood. In this study, we collected and analyzed samples from Harrat Rahat, focusing on the Shawahit unit. We found that the volcanic activity at Harrat Rahat was initiated by a mantle plume beneath a thinned lithosphere, and the changes in geochemistry can be attributed to a decrease in melt productivity and contamination.
Article
Geography, Physical
Khachatur Meliksetian, Iain Neill, Dan N. Barfod, Eilidh J. M. Milne, Emma C. Waters, Gevorg Navasardyan, Edmond Grigoryan, Valerie Olive, Nicholas Odling, Arkady Karakhanian
Summary: The Karkar monogenetic volcanic field in Syunik, SE Armenia, near the country's only geothermal energy test site, erupted fissure-fed trachybasaltic andesite to trachyandesite lavas on a trans-tensional segment of the Pambak-Sevan-Syunik Fault. High-resolution dating suggests a Holocene age for the youngest eruptions, with volcanic activity overlapping with Palaeolithic to Bronze Age human occupation and posing a minor lava inundation hazard. Further geochemical research is needed to understand magma storage depth and timescales, indicating potential for future geothermal energy development in the area.
QUATERNARY GEOCHRONOLOGY
(2021)
Article
Geochemistry & Geophysics
Abdullah Kaygusuz, Cem Yucel, Emre Aydincakir, Mehmet Ali Gucer, Gilles Ruffet
Summary: This study investigates the sources and evolutionary history of Middle Eocene volcanic rocks in the Eastern Pontides region of NE Turkey through whole-rock geochemistry, Sr-Nd isotopic, and 40Ar/39Ar age data analysis. The findings suggest that these volcanic rocks originated from a lithospheric mantle source enriched by fluids derived from subduction, in a post-collisional extensional tectonic setting.
MINERALOGY AND PETROLOGY
(2022)
Article
Geosciences, Multidisciplinary
F. Marra, G. L. Cardello, M. Gaeta, B. R. Jicha, P. Montone, E. M. Niespolo, S. Nomade, D. M. Palladino, A. Pereira, G. De Luca, F. Florindo, A. Frepoli, P. R. Renne, G. Sottili
Summary: In this study, the Quaternary Volsci Volcanic Field in central Italy was investigated with new geochronological data and compositional analysis of eruptive products. The research revealed a history of volcanic activity and its implications on magma systems and subduction processes. The fast ascent of primitive magma batches is suggested to be controlled by tectonic forces in a compressive stress field.
INTERNATIONAL JOURNAL OF EARTH SCIENCES
(2021)
Article
Geochemistry & Geophysics
Hyun-Ok Choi, Jonguk Kim, Jihye Oh, Chang Hwan Kim, Soon Young Choi, Won Hyuck Kim, Chan Hong Park
Summary: This study utilized mineralogy and geochemistry data from submarine volcanic rocks collected from various seamounts in the southwest of the East Sea to investigate the characteristics of magmas' sources, evolution, and storage conditions. The analyses revealed information about the ages of the samples, the compositions of rocks, and the thermobarometric conditions associated with Quaternary volcanism, shedding light on the formation and evolution of these seamounts.
Article
Geology
Igor M. Villa, Giulia Bosio
Summary: The substoichiometric potassium concentrations and low alkali occupation observed in biotite phenocrysts from marine tephra layers are likely the result of diagenetic alteration caused by exposure to interstitial water and brine intrusions. This alteration has been shown to affect potassium-argon ages, leading to discordance, high step ages, and anomalies in elemental ratios. The preferential leaching of potassium from the phyllosilicate interlayers and the shielding of radiogenic Ar* in the tetrahedral-octahedral-tetrahedral (T-O-T) phyllosilicate layer are proposed as mechanisms for the observed discrepancies.
Article
Geochemistry & Geophysics
Leah E. E. Morgan, Brett Davidheiser-Kroll, Klaudia F. F. Kuiper, Darren F. F. Mark, Noah M. M. McLean, Jan R. R. Wijbrans
Summary: The accuracy and traceability of geochronometers are crucial to questions asked by Earth scientists. This study focuses on the 40Ar/39Ar geochronometer and its co-irradiation with reference materials. The authors used various calibration methods to determine the ages of monitor minerals and found that the current results do not meet the desired accuracy, but the extensive methodology development presented in this study can help improve future measurements.
GEOSTANDARDS AND GEOANALYTICAL RESEARCH
(2023)
Article
Multidisciplinary Sciences
Kerry Sieh, Jason Herrin, Brian Jicha, Dayana Schonwalder Angel, James D. P. Moore, Paramesh Banerjee, Weerachat Wiwegwin, Vanpheng Sihavong, Brad Singer, Tawachai Chualaowanich, Punya Charusiri
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2020)
Review
Geography, Physical
J. E. T. Channell, B. S. Singer, B. R. Jicha
QUATERNARY SCIENCE REVIEWS
(2020)
Article
Geosciences, Multidisciplinary
Wen Lin, Janok P. Bhattacharya, Brian R. Jicha, Brad S. Singer, William Matthews
Summary: This study quantifies the global sea-level changes during the Late Cretaceous using high-resolution sequence stratigraphic analysis and new dating techniques, showing evidence of orbital climate control on sea-level changes. The synchronous relationships observed may suggest a glacio-eustatic origin for these high-frequency sequences.
GEOLOGICAL SOCIETY OF AMERICA BULLETIN
(2021)
Article
Geochemistry & Geophysics
Jacob D. Klug, Brad S. Singer, Noriko T. Kita, Michael J. Spicuzza
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2020)
Article
Geosciences, Multidisciplinary
Matthew M. Jones, Bradley B. Sageman, David Selby, Brian R. Jicha, Brad S. Singer, Alan L. Titus
Summary: The study successfully quantifies the duration of the hiatus at the base of OAE2 in the North American Western Interior Basin using new radiometric dating and chemostratigraphic research, advancing the chronostratigraphical understanding of the Cenomanian-Turonian boundary and showing the conformity of geochemical anomalies at the onset of OAE2. The rapid onset of OAE2 may be linked to large igneous province volcanism, with the addition of CO2 potentially driving changes in marine carbonate chemistry, as indicated by the new isotopic data.
GEOLOGICAL SOCIETY OF AMERICA BULLETIN
(2021)
Article
Geosciences, Multidisciplinary
Brad S. Singer, Brian R. Jicha, David Sawyer, Ireneusz Walaszczyk, Robert Buchwaldt, Jorg Mutterlose
GEOLOGICAL SOCIETY OF AMERICA BULLETIN
(2021)
Article
Geochemistry & Geophysics
Sarah F. Trevino, Craig A. Miller, Basil Tikoff, Dominique Fournier, Brad S. Singer
Summary: The Laguna del Maule volcanic field in Chile has witnessed frequent eruptions of rhyolite over the past centuries, with surface uplift recorded by paleo-shorelines and an inflation source near the Barrancas volcanic complex. A high-density magma body has been identified in the Barrancas region, indicating ongoing magma storage processes.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geology
David Kynaston, Janok P. Bhattacharya, Brad S. Singer, Brian R. Jicha
Summary: This paper documents a mudstone-prone tributary valley fill connected to a trunk valley in the Turonian Notom Delta of the Ferron Sandstone Member in Utah. Utilizing high-resolution 3D photogrammetry models and GPS surveys, the morphology of the tributary valley was restored and interpreted based on sedimentary facies and surface morphology. The study also used Ar-40/(39) Ar dating to re-evaluate depositional rates and timing, revealing a likely autogenic control of the fluvial stratigraphy.
JOURNAL OF SEDIMENTARY RESEARCH
(2021)
Article
Geosciences, Multidisciplinary
Laurie Brown, Brad S. Singer, Miriam Barquero-Molina
Summary: This study presents new 40Ar/39Ar ages and paleomagnetic data from a variety of ignimbrites and lava flows in the Central Volcanic Zone of the Andes, east of the Atacama Desert in Chile. The ignimbrites range in age from 4.2 Ma to 0.5 Ma, while the lava flows have ages ranging from 3.5 Ma to 0.1 Ma, with significant differences in paleomagnetic directions between the two rock types. The research also shows that the paleosecular variation in magnetic field direction at the study sites is larger than current models predicted.
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
(2021)
Article
Geosciences, Multidisciplinary
Emily E. Mixon, Brad S. Singer, Brian R. Jicha, Adan Ramirez
Summary: Calbuco volcano in the Andean Central Southern Volcanic Zone is considered one of the most dangerous volcanic centers in the Southern Andes by Chile's Geological Survey. Research suggests that Calbuco has produced a greater eruptive flux in the Pleistocene-Holocene period compared to other arc volcanoes globally.
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
(2021)
Article
Multidisciplinary Sciences
Allen J. Schaen, Blair Schoene, Josef Dufek, Brad S. Singer, Michael P. Eddy, Brian R. Jicha, John M. Cottle
Summary: Studies suggest that in an Andean pluton at a depth of 3 to 7 km with an age of about 7 to 6 million years, U-Pb zircon petrochronology and 40Ar/39Ar thermochronology were used to constrain silicic melt segregation and residual cumulate formation. Through thermo-petrological simulations linked to a zircon saturation model, spatiotemporal melt flux distributions were mapped, with findings indicating that around 50 km(3) of rhyolitic melt was extracted in approximately 130 ka.
Article
Geosciences, Multidisciplinary
L. Gordon Medaris, Brad S. Singer, Brian R. Jicha, David H. Malone, Joshua J. Schwartz, Esther K. Stewart, Amanda Van Lankvelt, Michael L. Williams, Peter W. Reiners
Summary: New geochronologic data from midcontinental Laurentia reveal that the emplacement of the 1476-1470 Ma Wolf River granitic batholith was accompanied by regional metamorphism, deformation, and sedimentation, as evidenced by features in the Baraboo Interval strata. This Baraboo orogeny, linking the Picuris orogeny to the southwest and the Pinware orogeny to the northeast, represents a unique transcontinental orogeny in the early Mesoproterozoic, characterized by a great width, predominance of ferroan granites, and regional high T-P metamorphism related to granitic magmas.
GEOSCIENCE FRONTIERS
(2021)
Article
Geochemistry & Geophysics
Emily E. Mixon, Brian R. Jicha, Damian Tootell, Brad S. Singer
Summary: This article introduces a new multi-collector noble gas spectrometer, the Isotopx NGX-600, optimized for 40Ar/39Ar measurements. The performance of the NGX-600 is evaluated and compared with other noble gas spectrometers through analysis of atmospheric argon. The study provides optimal measurement parameters, correction methods, and comparative analysis of volcanic rock samples.
Article
Geography, Physical
Jacob D. Klug, Adan Ramirez, Brad S. Singer, Brian R. Jicha, Emily E. Mixon, Paola Martinez
Summary: Accurate and precise dating of Quaternary lavas and pyroclastic flow or fall deposits is crucial for understanding the evolution and assessing the hazards of active volcanoes. An intercalibration exercise between two laboratories was conducted to refine the 40Ar/39Ar dating method for young volcanic materials. The results showed consistent ages between the two labs, significantly improving our understanding of the temporal evolution of these volcanoes.
QUATERNARY GEOCHRONOLOGY
(2022)
Article
Geochemistry & Geophysics
Youjuan Li, Brian R. Jicha, Zhiqiang Yu, Huaichun Wu, Xiaolin Wang, Brad S. Singer, Huaiyu He, Zhonghe Zhou
Summary: The Early Cretaceous Jehol Biota in Liaoning Province, China, provides important insights into the evolution and radiation of fauna. The precise dating of fossil beds using 40Ar/39Ar ages reveals that the Lujiatun and Jianshangou beds were deposited nearly contemporaneously, and the mass mortality events reflected by dinosaur and feathered dinosaur/primitive bird fossils were short-lived.
EARTH AND PLANETARY SCIENCE LETTERS
(2022)