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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 50 (1966)

Issue: 3. (March)

First Page: 617

Last Page: 617

Title: Coral Pinnacle Sedimentation, Alacran Reef Lagoon, Mexico: ABSTRACT

Author(s): Charles M. Hoskin

Article Type: Meeting abstract

Abstract:

Coral pinnacles growing in Alacran Reef lagoon can be characterized by three different depositional environments. These are: (1) pinnacle crest--a rigid framework of living colonial corals and unconsolidated sediment which is poorly sorted, consisting of 2.5^phgrv coral sand, with relatively high permeability, 20% calcite (90% aragonite), and 1-1.7% magnesium; (2) pinnacle slope--a transitional environment which accumulates very poorly sorted mixtures of gravelly coral, Halimeda sand and silt, having relatively low permeability, 10% calcite (90% aragonite), and 1% magnesium; and (3) lagoon floor--a topographic basin in which is accumulated poorly sorted 4.5^phgrv

Observed diagenetic processes are: (1) pelleting of lagoon-floor mud, (2) formation of galleries in the rigid framework by lithophagid pelecypods and in coral and mollusk sediment grains by boring algae, (3) growth of euhedral aragonite crystals in grain cavities, and (4) recrystallization of coral grains. Expected diagenetic processes in the future are cementation and dolomitization of pinnacle-crest sand, compaction of lagoon-floor mud, and mold-porosity formation in the rigid framework and in sediments of all three environments.

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Copyright 1997 American Association of Petroleum Geologists