ALBERT

Description: Gases present in the Earth crust are important in various branches of human activities. Hydrocarbons are a significant energy resource, helium is applied in many high-tech instruments, and studies of crustal gas dynamics provide insight in the geodynamic processes and help monitor seismic and volcanic hazards. Quantitative analysis of methane and CO2 migration is important for climate change studies. Some of them are toxic (H2S, CO2, CO); radon is responsible for the major part of human radiation dose. The development of analytical techniques in gas geochemistry creates opportunities of applying this science in numerous fields. Noble gases, hydrocarbons, CO2, N2, H2, CO, and Hg vapor are measured by advanced methods in various environments and matrices including fluid inclusions. Following the “Geochemical Applications of Noble Gases”(2009), “Frontiers in Gas Geochemistry” (2013), and “Progress in the Application of Gas Geochemistry to Geothermal, Tectonic and Magmatic Studies” (2017) published as special issues of Chemical Geology and “Gas geochemistry: From conventional to unconventional domains” (2018) published as a special issue of Marine and Petroleum Geology, this volume continues the tradition of publishing papers reflecting the diversity in scope and application of gas geochemistry.

Description: Published

Description: 976190

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: JCR Journal

Description: Natural hydrocarbon seepage is a widespread phenomenon in sedimentary basins, with important implications in petroleum exploration and emission of greenhouse gases to the atmosphere. China has vast petroleum (oil and gas) bearing sedimentary basins, but hydrocarbon seepage has rarely been the object of systematic studies and measurements. Based on the available Chinese literature, we report a first inventory of 932 hydrocarbon seeps or seepage zones (710 onshore seeps and 222 offshore seeps), including 81 mud volcanoes, 449 oil seeps, 215 gas seeps, and 187 solid seeps (bitumen outcrops). The seeps are located within the main 20 Mesozoic-Cenozoic petroliferous sedimentary basins, especially along the marginal, regional and local faults. The type of manifestations (oil, gas or mud volcano) reflects the type and maturity of the subsurface petroleum system and the sedimentary conditions of the basin. Oil seeps are particularly abundant in the Junggar Basin. Gas seeps mostly developed in the Lunpola Basin, in smaller basins of the eastern Guizhou and Yunnan provinces, onshore Taiwan and in the offshore Yinggehai Basin. Mud volcanoes developed in basins (Junggar, Qaidam, Qiangtang, onshore and offshore Taiwan) that experienced rapid sedimentation, which induced gravitative instability of shales and diapirism. In comparison to available global onshore seep data-bases, China results to be the country with the highest number of seeps in the world. The massive gas seepage in China could represent a considerable natural source of methane to the atmosphere, and a key process that may drive future hydrocarbon exploration.

Description: Published

Description: 269-284

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: JCR Journal

Description: Mantle degassing transect across different tectonic units within a plate convergent setting has been well documented for oceanic convergent margins by systematic changes in geochemistry (e.g., 3He/4He, d13C, and CO2/3He) of hydrothermal gases. However, little is known about spatial variations in volatile geochemistry across a continental convergent margin. In this study, we identify a mantle degassing transect in the southeastern Tibetan Plateau using He-CO2 systematics of hydrothermal gases, which extends from India-Asia continental convergent margin to intra-continent extensional region. d13C-CO2 ( 11.8‰ to 3.1‰) and CO2/3He (1.7 108 to 7.1 1011) values of hydrothermal gases show large variations that are consistent with modification by secondary physico-chemical processes, such as multi-component mixing, hydrothermal degassing, and calcite precipitation. Three levels of He degassing can be recognized based on 3He/4He dataset (0.01–5.87 RA) of the hydrothermal gas samples and their distances to volcanic centers. A magmatic level He degassing (35–74% mantle He) is found near active and/or Quaternary volcanoes fed by mantle-derived magmas. With increasing distance to volcanic centers, the outgassed magmatic volatiles are gradually diluted by crustal components (e.g., radiogenic 4He), defining a transitional level He degassing (13–33% mantle He). The 3He/4He values (8.16–8.48 RA) of olivine phenocrysts indicate a MORB (mid-ocean ridge basalts)-type mantle source for the magmatic and transitional levels of He degassing that are localized in Quaternary volcanic fields. In contrast, a background level He degassing (〈12% mantle He) dominates the entire study area, and can be attributed to (i) degassing of sub-continental lithospheric mantle, and/or (ii) higher degrees of crustal contamination than those of the transitional level He degassing near volcanic centers. Combined with olivine 3He/4He data reported in this study and whole-rock 87Sr/86Sr data of host basalts from literature, source components of the mantle-derived magmas are suggested to include the MORB-type convective mantle, subducted Indian slab materials, and less degassed mantle materials, which can account for the possible decoupling between He and Sr isotope systematics. These findings delineate the origin and outgassing of mantle volatiles controlled by the India-Asia continental convergence, and would contribute to a better understanding of the deeply-sourced volatile emissions in these tectonic settings.

Description: Published

Description: 61-78

Description: 9T. Geochimica dei fluidi applicata allo studio e al monitoraggio di aree sismiche

Description: JCR Journal

Description: Geosphere is constantly crossed by fluid fluxes of varying flow velocity and chemical composition. The development of gas geochemistry techniques over the last 50 years allowed of gaining a significant understanding of gas accumulations, gas fluxes, and their geological sources. Although gas geochemistry is a relatively recent discipline of geochemistry, advancements over the last 2 decades in sampling, storage and analysis of gas samples have enabled gas geochemistry to emerge as a critical scientific tool for constraining processes occurring in the geosciences. Chemical and isotopic features of various gas species have provided critical information about their origin, source, migration, and accumulation in specific environments, making gas geochemistry a widely used tool in a variety of fields of geosciences, including environmental/climate problems, geohazards, origin and evolution of rocks, as well as biogeochemical processes involving microbial activity. Due to the economic relevance of hydrocarbons and hydrothermal gases, they have been investigated more intensively than other gas types since very early time. Additionally, advances in our understanding of unconventional gases such as shale and tight gas in recent decades, represent new applications for these gas-related approaches. Over the last half-century, scientists in the field of gas geochemistry have exchanged their findings/experiments at major international scientific conferences organized by the International Conference on Gas Geochemistry (ICGG), the Geochemical Society, the American Geophysical Union (AGU), the European Geosciences Union (EGU), the American Association of Petroleum Geologists (AAPG), and the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI). Numerous applications of gas geochemistry in geology and the environment have been studied in recent years, and the present trend confirms that Earth and Environmental Sciences are the most promising domains for gas geochemistry applications. It is worth noting that advances in our understanding of noble/rare gas geochemistry are more closely tied to technology achievements than to fundamental geological knowledge. The current Research Topic has been devoted of compiling the most recent and pertinent experiences in the various domains of gas geochemistry. 23 papers presented but not limited in the 2019 ICGG meeting in Sicily have been accepted for publication. Hereby it is useful to report the list of published papers by date of publications and a keyword at the end in parentheses able to roughly identify the basic field of interest. In particular the paper by: (1) Qin et al. reported about Genetic Types, Distribution Patterns and Enrichment Mechanisms of Helium in China’s Petroliferous Basins (raw materials) (2) Xia et al. reported about The Characteristics of Organic Carbon in the Offshore Sediments Surrounding the Leizhou Peninsula, China (hydrocarbons) (3) Xiaobo et al. reported about Differences on Geochemical Characteristics and Their Implicating Significances of Nitrogen in Coal-Derived Gas and Oil-typed Gas in China (hydrocarbons) (4) Wu et al. reported about Inversion Characteristics of Hydrocarbon Gases Carbon Isotopes Varying With Temperature and Implications for Shale Exploration (hydrocarbons) (5) Longo et al. reported about Black Sea Methane Flares From the Seafloor: Tracking Outgassing by Using Passive Acoustics (hydrocarbons) (6) Nicula et al. reported about Geochemical Features of the Thermal and Mineral Waters From the Apuseni Mountains (Romania) (geothermics) (7) Melián et al. reported about Insights from Fumarole Gas Geochemistry on the Recent Volcanic Unrest of Pico do Fogo, Cape Verde (volcanic risk) (8) Nguyễn et al. reported about Radioactive Thoron 220Rn Exhalation From Unfired Mud Building Material Into Room Air of Earthen Dwellings (radioprotection in living environment) (9) Wang et al. reported about Potential Production of Carbon Gases and Their Responses to Paleoclimate Conditions: An Example From Xiaolongtan Basin, Southeast Tibetan Plateau (hydrocarbons) (10) Chen et al. reported about Factors Controlling Natural Gas Accumulation in the Southern Margin of Junggar Basin and Potential Exploration Targets (hydrocarbon) (11) Liang et al. reported about Preliminary Experimental Study of Methane Adsorption Capacity in Shale After Brittle Deformation Under Uniaxial Compression (hydrocarbons) (12) Ni et al. reported about Geochemical Comparison of the Deep Gases From the Sichuan and Tarim Basins, China (hydrocarbons) (13) Daskalopoulou et al. reported about Insight Into Hartoušov Mofette, Czech Republic: Tales by the Fluids (tectonophysics) (14) Gao et al. reported about Characteristics of Organic Matter and Biomarkers in Core Sediments From the Offshore Area of Leizhou Peninsula, South China Sea (hydrocarbons) (15) Cao et al. reported about The Paleoclimate Significance of the δ13C Composition of Individual Hydrocarbon Compounds in the Maoming Oil Shales, China (hydrocarbons) (16) Zhang et al. reported about Geochemical Characteristics of Gas and Flowback Water in Lake Facies Shale: A Case Study From the Junggar Basin, China (hydrocarbons) (17) Sun et al. reported about Soil Degassing From the Xianshuihe–Xiaojiang Fault System at the Eastern Boundary of the Chuan–Dian Rhombic Block, Southwest China (tectonophysics) (18) Xiaowei et al. reported about Catalytic Hydrogenation of Post-Mature Hydrocarbon Source Rocks Under Deep- Derived Fluids: An Example of Early Cambrian Yurtus Formation, Tarim Basin, NW China (hydrocarbons) (19) Fu et al. reported about An Automatic System for Continuous Monitoring and Sampling of Groundwater Geochemistry in Earthquake-Prone Regions of SW Taiwan (tectonophysics) (20) Kim et al. reported about Short-Term Monitoring of Geogenic Soil CO2 Flux in a Non-Volcanic and Seismically Inactive Emission Site, South Korea (tectonophysics) (21) Sano et al. reported about Groundwater Anomaly Related to CCS-CO2 Injection and the 2018 Hokkaido Eastern Iburi Earthquake in Japan (carbon capture and storage) (22) Siino et al. reported about Stochastic Models for Radon Daily Time Series: Seasonality, Stationarity, and Long-Range Dependence Detection (data processing) (23) Zafrir et al. reported about The Impact of Atmospheric and Tectonic Constraints on Radon-222 and Carbon Dioxide Flow in Geological Porous Media—A Dozen-Year Research Summary (tectonophysics)

Description: Published

Description: 936733

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: JCR Journal

Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Zhang, M., Guo, Z., Xu, S., Barry, P. H., Sano, Y., Zhang, L., Halldorsson, S. A., Chen, A.-T., Cheng, Z., Liu, C.-Q., Li, S.-L., Lang, Y.-C., Zheng, G., Li, Z., Li, L., & Li, Y. Linking deeply-sourced volatile emissions to plateau growth dynamics in southeastern Tibetan Plateau. Nature Communications, 12(1), (2021): 4157, https://doi.org/10.1038/s41467-021-24415-y.

Description: The episodic growth of high-elevation orogenic plateaux is controlled by a series of geodynamic processes. However, determining the underlying mechanisms that drive plateau growth dynamics over geological history and constraining the depths at which growth originates, remains challenging. Here we present He-CO2-N2 systematics of hydrothermal fluids that reveal the existence of a lithospheric-scale fault system in the southeastern Tibetan Plateau, whereby multi-stage plateau growth occurred in the geological past and continues to the present. He isotopes provide unambiguous evidence for the involvement of mantle-scale dynamics in lateral expansion and localized surface uplift of the Tibetan Plateau. The excellent correlation between 3He/4He values and strain rates, along the strike of Indian indentation into Asia, suggests non-uniform distribution of stresses between the plateau boundary and interior, which modulate southeastward growth of the Tibetan Plateau within the context of India-Asia convergence. Our results demonstrate that deeply-sourced volatile geochemistry can be used to constrain deep dynamic processes involved in orogenic plateau growth.

Description: This work was supported by China Seismic Experimental Site (CSES) (2019CSES0104), the Strategic Priority Research Program (B) of Chinese Academy of Sciences (XDB26000000), the National Key Research and Development Program of China (2020YFA0607700), the National Natural Science Foundation of China (41930642, 41602341, 41772355, and 41702361), the Second Tibetan Plateau Scientific Expedition and Research Program (STEP) (2019QZKK0702), and the United Laboratory of High-Pressure Physics and Earthquake Science (2019HPPES02). P.H.B. was supported by the US National Science Foundation EAR Grant 1144559 during a portion of this work.