About this Research Topic
Ascending fluid flow is ubiquitous in groundwater systems that dominate the uppermost part of the Earth's crust. Where fluids of varied composition migrate across different lithologies under changing Pressure-Temperature (P-T) conditions, ample possibilities arise for diverse dissolutional mechanisms to operate, creating the potential for hypogene karstification. Recent studies have revealed the globally widespread, although spatially uneven, development of hypogene karst within the upper (at least 4-5 km) crust, in a wide range of physicochemical conditions, types of rocks, and geodynamic settings, in both the continental and oceanic domains.
Hypogene karstification generates macroscopic void-conduit systems and promotes organization of fluid flow by influencing diagenetic processes, enhancing effective porosity and facilitating fluid migration. By this virtue, hypogene karst results in geochemical and geothermal anomalies and plays an important (often crucial) role in the formation of hydrocarbon, mineral, and geothermal resources, particularly in carbonate rocks. Although our understanding of hypogene karst has been significantly advanced during the last decade, many important aspects remain poorly documented and understood. Manuscripts focusing on one of the following or related points are particularly welcome:
• Deep-seated hydrogeology and the complex evolution and interaction of flow systems of different nature as major controlling factors of hypogene karstification;
• The role of basement fluids originating from the lower crust and/or the mantle, particularly in regions where the lithosphere has been activated by mantle plumes and asthenospheric rises;
• Dissolution potential of raising basinal and other endogene fluids with respect to different rock-forming minerals under various P-T conditions;
• Relations of speleogenesis (that is, dissolution-dominated formation of macroscopic void-conduit systems) with other processes of fluid-induced transformations of rocks, e.g., metasomatism;
• Geological and geodynamic controls on hypogene karstification;
• Role of hypogene karstification in the modification of reservoir properties and mineralogy in hydrocarbon and mineral resources;
• Role of hypogene karstification in the subsequent development of epigene karst and surface landforms (e.g., when hypogene void-conduit systems are shifted into the shallow subsurface and exposed).
Although studies based on direct examination of relict cave and karst features in the shallow subsurface are indispensable and welcome, we particularly encourage studies dealing with deep-seated hypogene karst based on indirect evidence such as geophysics, mineralogy and geochemistry, fluid dynamics modeling, and other prospecting and exploration techniques.
One of the goals of this Research Topic is to bridge the gap and facilitate knowledge transfer between researchers working in the general field of karst studies and those working in other fields, such as reservoir studies, burial diagenesis, hydrocarbon and geothermal exploration, sequestration of CO2, etc., where recognition of the concept of hypogene karst may bring about important scientific advances. We welcome all article types, with a particular emphasis on Original Research, Reviews and Perspectives.
Topic Editor Cathy Hollis currently receives research funding (expires Sept 2020) from BP, Wintershall DEA, Woodside and Tullow Oil. The other Topic Editors declare no competing interests with regard to the Research Topic subject.
Keywords: hypogene karst, burial dissolution, fluid-rock interaction, deep hydrogeology, reservoir characterization
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