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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 69 (1985)

Issue: 2. (February)

First Page: 272

Last Page: 273

Title: Disrupted Carbonate Hardgrounds in Shallow Carbonate-Shelf Sediments: Origin and Setting of Tepees and Their Associated Fabrics: ABSTRACT

Author(s): Christopher G. Kendall, John K. Warren

Article Type: Meeting abstract


Carbonate-sediment surface hardgrounds are commonly disrupted and brecciated. Some of these breccias are the result of repeated episodes of fracturing and fracture fill by sediment and/or cement. Each fracture and fracture-fill phase causes the crust to grow in surface area and crumples it into megapolygons whose anteform margins are called tepees. Fracturing is caused by thermal contraction, water-table movement buoying up the crust, mass movement of sediment, and tectonic events. Tepees are commonly ascribed to tidal flats but, in fact, also occur in many settings that can be determined from their fabric and facies associations. (1) Submarine tepees from shallow, carbonate-saturated water occur in fractured, bedded, marine grainstones with acicular and micritic cements. They contain no vadose pisolites or gravity cements, and the hardground surface is altered and bored. (2) Peritidal tepees occur in fractured, bedded, tidal-flat carbonates characterized by fenestral, pisolitic, and laminar algal fabrics close to the marine water table. Fracture fills include gravity-controlled marine travertine and/or marine and terra rossa sediments. (3) Groundwater tepees form in fractured fenestral, pisolitic, and laminar algal crusts over "boxwork" carbonates at the margin of shallow salinas where periodic groundwater resurgence is common. (4) Extrusion tepees, which are also from salina margins with periodic groundwater resurgence, form in crusts coated with laminated micrite that extend from the fractures downward into dolomitic micrite. (5) Caliche tepees, from c ntinental settings overlying soil profiles, form in

End_Page 272------------------------------

laminar crusts with pisolites. Fractures are filled by micritic laminae, microspar, spar, and terra rossa.

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Copyright 1997 American Association of Petroleum Geologists