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Publication Date

March 2012

Abstract

In carbonate rocks, especially in those with high primary porosity such as most Cenozoic carbonates, the interaction between deeply derived rising flow through sub-vertical fracture-controlled conduits and intrastratal matrix flow of shallower systems can invoke mixing corrosion and result in prominent speleogenetic effects. This paper outlines a conceptual model of such interaction and provides instructive field examples of relevant morphological effects from two different regions within the Prichernomorsky (north Black Sea) basin, where karst features are developed in lower Pliocene, Eocene and Paleocene limestones. In the Crimean fore-mountain region, extensive steep to vertical limestone scarps formed through recent exposure of hypogenic fracture-controlled conduits provide outstanding possibilities to directly examine details of the original karstic porosity. The morphological effects of the conduit/matrix interaction, documented in both caves and exposed scarps, include lateral widening of sub-vertical conduits within the interaction intervals (formation of lateral notches and niches) and the development of side bedding-parallel conduits, pockets and vuggy-spongework zones. Natural convection circulation, invoked by interaction of the two flow systems, spreads the morphological effects throughout the conduit space above the interaction interval. Where the interaction of the two flow systems is particularly strongly localized, such as along junctions of two vertical fracture sets, the resultant morphological effect can take the form of isolated chambers. The variety of speleogenetic features developed through the conduit/matrix interaction, can be broadly grouped into two categories: 1) variously shaped swells of the major fracture conduit itself (morphological features of its walls – niches and pockets), and 2) features of the vuggy-spongework halo surrounding the conduit. This halo includes clustered and stratiform cavities, spongework zones and lateral side conduits. The speleogenetic features due to cond

Notes

International Journal of Speleology, Vol. 41, no. 2 (2012-03-26).

Keywords

Multiple Porosity Systems, Conduit/Matrix Interaction, Hypogenic Speleogenesis, Cenozoic Carbonates, North Black Sea, Odessa, Crimea

Description

RDA

Subject: topical

Multiple Porosity Systems; Conduit/Matrix Interaction; Hypogenic Speleogenesis; Cenozoic Carbonates; North Black Sea; Odessa; Crimea

Type

Article

Genre

serial

Identifier

K26-05760

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