159-9 Suggested Origin of Middle Paleozoic Hypogene Karst from Pacific Floor Subducted Slab Walls

Session: Hypogene Speleogenesis: An Overview of Research in Memory of Dr. Alexander Klimchouk

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Investigation of karst typically involves geomorphology and shallow hydrology investigations and exploration of caves. Paleokarst has often been overlooked. Caves are known to form in almost all lithologies, only requiring enough geological time and variable, sometimes extreme conditions. Lowe (1991) uses inception horizons: faults, unconformities, and shale beds, as cave/conduit pathway initiators, inferred timing is as far back as post lithification and diagenesis. Some caves have known hydrothermal association and ore deposits often replace carbonates and are often found in paleokarst.

We should change our perspective and think more extensively.  Recent interpretation of seismic data and 3D tomographic imaging of subducted Pacific Floor slabs from ~180 Ma shows no flat slab subduction, but, in most cases, rather, steep slab failure and treacle-like pile up in the mantle (Sigloch and Mihalynuk, 2017). In addition, offshore terrane collisions are known from tracked plate motions, mapping and advanced paleomagnetic data, explaining formation of the Rockies, hot spots and rifting zones across the North American Plate. 

Subducted Pacific Floor slab pile ups have been beneath the westward drifting North American Plate causing magmatic activity. During Wilson Cycle Atlantic suturing western Europe could also be involved.  Subducted slab walls show in 3D tomographic images to – 1,800 km depth (Sigloch, 2013).  This suggests correlation of slab-wall-derived magmatic activity forming hypogene karst, (later paleokarst), in Mid Paleozoic (Early Mississippian/ Carboniferous) rocks. Radiometric dates of secondary deposits support and bracket this along with slab sinking rates and NA plate drift rate.  

An intense maze cave in south central Tennessee is formed in both clastic and carbonate rocks through the complicated and incomplete Silurian-Devonian-Mississippian stratigraphic interval. The cave has hydrothermal features as well as more recent fluvial features. The setting has multiple thin beds, clastic, carbonate, abrupt lithological changes, unconformities, missing lithologies and sediment deformation, suggesting that the cave’s origin might be from many processes, somewhat catastrophic?  The cave stream has normal temperature but extremely low dissolved solutes similar to Fort Payne Formation water (that formation contains part of the cave).  Less likely it is from the Precambrian Granite-Rhyolite province continental basement, - 1,520 m deep. However, a nearby well has penetrated water of similar chemistry near this depth (~1,500 m) in the Upper Cambrian (Knox Group) Copper Ridge Dolomite. 

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11099

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