Article
Geochemistry & Geophysics
L. Notini, M. Scambelluri, A. Tommasi, A. Zanetti, F. Ferri, A. Rodriguez-Vargas, E. Rampone
Summary: This study provides important petrologic information on the mantle wedge above an active subduction zone in Southern Colombia. The researchers analyzed a unique suite of rock samples and found evidence of hydration, metasomatism, and partial melting in the mantle wedge. They also observed variations in lithotypes, textures, and mineral abundance, indicating different interactions with melts and fluids. This study sheds light on the complex petrological processes occurring in the mantle wedge and contributes to our understanding of subduction zone dynamics.
Article
Geochemistry & Geophysics
Douglas Almeida Silveira, Paola Ferreira Barbosa, Cassiano Costa e Castro, Guilherme Ferreira da Silva, Joseneusa Brilhante Rodrigues
Summary: This study analyzed apatite grains from the Angico dos Dias Carbonatite Complex region in Brazil using an electron probe microanalyzer. The results showed that the apatite grains had characteristics of metacarbonatitic lithotypes and some had undergone substitution processes. Statistical analysis helped identify the sources of the apatite grains and confirmed the presence of carbonatitic bodies in the area.
JOURNAL OF GEOCHEMICAL EXPLORATION
(2024)
Article
Geochemistry & Geophysics
Jia-Min Wang, Kyle Patrick Larson, Jin-Jiang Zhang, Liang Zhao, Fu-Yuan Wu
Summary: The role of collisional belts in the global carbon budget is controversial. This study reveals a previously unrecognized carbon source in the collisional orogen of the Himalayas, where metamorphism of carbonate-bearing rocks in the hanging wall resulted in significant CO2 degassing.
Article
Geochemistry & Geophysics
Om Prakash Kumar, Amiya S. Naik, P. Gopinathan, T. Subramani, Vishvajeet Singh, Prakash K. Singh, Uma K. Shukla, Arun Prabhu
Summary: This study characterizes lignite samples from Kapurdi, Giral, and Sonari mines in Rajasthan's Barmer Basin using petrographic and geochemical techniques. The results provide insights into the geochemical properties, hydrocarbon potential, depositional environment, and paleo-climatic conditions of these lignite deposits. The study finds high volatile matter and sulfur concentrations in the Barmer lignite deposits, as well as indications of a wet environment during organic material decomposition. The findings have implications for understanding the coalification profile and hydrocarbon source rock potential in the region.
JOURNAL OF GEOCHEMICAL EXPLORATION
(2024)
Review
Geochemistry & Geophysics
Ashkan Jahandari, Behnam Abbasnejad
Summary: The assessment of heavy metal concentrations in agricultural soil is important for crop safety and quality, as well as potential risks to human health. This review analyzed published data on seven heavy metals in Iranian farmland soils and found that nickel and cadmium exceeded permissible levels. Arsenic showed significant contamination in multiple provinces, while lead and cadmium were highly contaminated in Fars province. Overall, the contamination levels of heavy metals in Iranian agricultural soils were relatively low.
JOURNAL OF GEOCHEMICAL EXPLORATION
(2024)
Article
Geochemistry & Geophysics
Xiguang Huang, Jun He, Jingxin Zhao, Jingzhao Dou, Weiyong Li, Aimin Hu, Ge Liu, Yiru Ji, Fukun Chen, Shuangqing Li
Summary: This study investigates the zircon ages and whole-rock geochemical data of Late Paleozoic magmatic rocks in the Western Yunnan Tethyan belt to identify the origin and mechanism of mantle melting. The results suggest that these magmatic rocks may originate from different mantle domains that were metasomatized by slab-derived fluids and sediment-derived melts.
Article
Geochemistry & Geophysics
Huichuan Liu, Alan R. Hastie, Chiara Maria Petrone
Summary: This study conducted isotope analyses on two ocean island basalt (OIB)-associated enriched mafic intrusions in the Yunnan-Burma region, and found that these rocks may have originated from the subduction recycling of marine sediments and altered oceanic crust.
Article
Geochemistry & Geophysics
Huanting Hu, Benjamin H. Passey, Sophie B. Lehmann, Naomi E. Levin, Beverly J. Johnson
Summary: The O-18/O-16 ratios of biominerals are influenced by various factors, including regional climate, local hydrology, and behavioral and physiological factors. The addition of O-17 allows for further resolution of these factors. The study presents a triple oxygen isotope mass balance model and evaluates it against data from modern and fossil animals. The model predicts that animals in arid environments have wider ranges and lower minimum values of body water Delta'O-17, and leaf water consumers are more sensitive to relative humidity variations.
Article
Geochemistry & Geophysics
Aaron Meilijson, Or M. Bialik, F. Garrett Boudinot, Paul R. Bown, Chaim Benjamini, Nicolas D. Waldmann, Julio Sepulveda
Summary: This study addresses the role of various transport mechanisms in transferring organic matter from continental and shallow marine settings into deep-marine environments. The study demonstrates how these mechanisms contribute to the long-term burial of organic carbon in marine systems, highlighting the importance of sediment transport for the global carbon cycle.
Article
Geochemistry & Geophysics
Philip A. E. Pogge von Strandmann, Lara R. Cosford, Chun-Yao Liu, Xianyi Liu, Alexander J. Krause, David J. Wilson, Xiaoqing He, Alex J. McCoy-West, Sigurour R. Gislason, Kevin W. Burton
Summary: This study investigates the impact of riverine discharge and weathering intensity on lithium isotopes in a mono-lithological terrain using Icelandic rivers as the case study. The results show that water-rock interaction time is a primary control on the fractionation of Li isotopes. The relationship between weathering intensity and delta 7Li is observed in these basaltic rivers, but with different values compared to global rivers due to lithological control. The study also highlights the varying fractionation between the clay fraction and the dissolved load with both W/D and discharge. Overall, this study confirms the utility of Li isotopes as a tracer of weathering processes and provides important insights for interpreting detrital delta 7Li values.
Article
Geochemistry & Geophysics
Miguel Bernecker, Sven Hofmann, Philip Tauxe Staudigel, Amelia Jane Davies, Mattia Tagliavento, Niels Meijer, Armelle Ballian, Jens Fiebig
Summary: The analysis of CO2 released from phosphoric acid digestion of carbonates can help identify the rate-limiting kinetic processes involved in carbonate mineralization and determine the formation temperatures. A robust methodology for high-precision triple clumped isotope analysis using gas and carbonate preparation lines and mass spectrometry is outlined. The stability of mass spectrometric measurements can be monitored using reference gas intensity.
Article
Geochemistry & Geophysics
Yilun Xu, Dandan Li, Yuan Gao, Menghan Li, Lilin Sun, Xiaolin Zhang, Chengshan Wang, Yanan Shen
Summary: This study investigates the origin of organic-rich Upper Cretaceous source rocks in the Songliao Basin. By analyzing S-isotopic compositions of pyrite, evidence of significant seawater incursions is found, suggesting the importance of marine incursions in the formation of oil source rocks.
Article
Geochemistry & Geophysics
Jian Zhang, Dominique Genty, Colette Sirieix, Cecile Verdet, Sylvain Mateo, Ludovic Devaux, Giovanni Sgubin, Stephane Bujan, Benedicte Minster, Edouard Regnier, Ting-Yong Li, Francois Bourges, Chaojun Chen, Ming-Qiang Liang, Chaojum Chen, Vincent Marieu
Summary: The understanding of infiltration in caves and karst terrains is complicated due to the heterogeneity of limestone fissures, conduits, and reservoirs. Through the use of isotopic data and a conceptual model, this study found seasonal variability and time delays between water excess and drip rates in different cave levels, as well as the impact of multiple infiltration routes and karst reservoir dynamics on isotopic differences. These results are important for understanding infiltration in karstic zones and interpreting speleothem isotopic records in paleo-climate studies.
Article
Geochemistry & Geophysics
Timothy Csernica, Alex L. Sessions, John M. Eiler
Summary: The abundances of isotopologues, or different isotopic forms of a compound, vary based on its physical and chemical history. Due to the challenges of separating and observing isotopologues, only a few dimensions of isotopic diversity are routinely measured. This article presents an experimental method using Q Exactive HF Orbitrap to observe isotopic forms of methionine, demonstrating the diversity of observable and interpretable isotopic constraints for organic molecules.
Article
Geochemistry & Geophysics
Derek R. Knaack, Matthew I. Leybourne, Daniel Layton-Matthews, James R. Hein, Robert J. Stern, Richard Wysoczanski, Kevin Faure, Akira Usui, Tom Al, Andrew McDonald, Agatha Dobosz, Peir Pufahl
Summary: Ferromanganese precipitates, such as crusts, nodules, and hydrothermal deposits, exhibit negative Delta'17O values due to the incorporation of various oxygen sources. However, the understanding of their triple oxygen isotope systematics is limited. This study evaluates the factors contributing to the triple oxygen isotopic composition of different genetic types of Fe-Mn precipitates and their formation environments. The results show variations in delta'18O and Delta'17O values among different types of Fe-Mn precipitates, suggesting the influence of oxygen sources. The triple oxygen isotope ratios of Fe-Mn precipitates reflect complex processes and mixing of multiple sources, and can provide insights into paleoenvironmental conditions at the time of formation.
Article
Geochemistry & Geophysics
Ana S. Casas, Kai-Uwe Hess, James Badro, Michael Eitel, Donald B. Dingwell
Summary: The viscosity of molten Earth mantle has been determined for various redox states, showing a decreasing trend with increasing iron redox state. Additionally, an increase in glass transition temperatures with increasing melt depolymerisation is observed.
Article
Geochemistry & Geophysics
Guoliang Zhang, Junhua Yao, Feng Xu, Tao Wu, Chun-Feng Li, Shuai Wang
Summary: This study provides mineralogical and geochemical analyses of basalts and serpentinized peridotites from the Mussau Trench. The results show that the basalts have geochemical characteristics different from typical arc lavas, possibly indicating formation along a transform fault in the Caroline Plate. The serpentinized peridotites in the Mussau Trench have distinct compositions compared to other regions, suggesting they originated from the lithosphere of the Caroline Plate. The estimated temperature and pressure indicate serpentinization by high-temperature fluids derived from the subducted slab. The serpentinized peridotites and basalts in the Mussau Trench are important for understanding the processes of intra-oceanic subduction initiation.
Article
Geochemistry & Geophysics
Lucia Ojeda, Giuseppe Etiope, Pablo Jimenez-Gavilan, Ildiko Melinda Martonos, Thomas Rockmann, Maria Elena Popa, Malavika Sivan, Antonio Fermin Castro-Gamez, Jose Benavente, Inaki Vadillo
Summary: This study investigates the origin of methane released in hyperalkaline springs in the Ronda Peridotite Massifs in southern Spain using various data analysis methods. The results show that the isotopes of methane in the springs are relatively stable, and variations in hydrogen and methane concentrations may be due to changes in gas pressure and migration intensity. The interpretation of methane origin based on clumped isotopes is uncertain, while the amount of Total Organic Carbon is correlated with the origin of methane.
Article
Geochemistry & Geophysics
M. Moklesur Rahman, Ling Bai
Summary: The importance of proper seismic hazard assessment for the eastern Himalaya syntaxis region, due to its complex tectonic position and long history of devastating earthquakes, has been highlighted. Probabilistic seismic hazards are computed, combining area, linear, and smooth grid seismogenic source models, and incorporating surface topography and site effects. The analysis estimates mean seismicity rate, b-value, and expected maximum magnitude using the Maximum Likelihood Algorithm. Ground motion prediction equations are assigned to each source model to reduce uncertainties in hazard calculation. Hazard maps show a wide range of spatio-temporal variation in peak ground acceleration and spectral acceleration.
PURE AND APPLIED GEOPHYSICS
(2023)
Article
Geochemistry & Geophysics
Samuel N. Perry, Virginia G. Rodriguez, Peter C. Burns
Summary: This study demonstrates the existence of a persistent nanoscale aqueous uranyl carbonate macroion using mass spectrometry under environmentally relevant pH conditions.
