Diagenesis of Isla de Mona, Puerto Rico

Conference · Tue May 01 00:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:6701828

Gonzalez, L A ^[1]; Ruiz, H; Monell, V ^[2]

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1. Univ. of Iowa, Iowa City (USA)
2. Univ. of Puerto Rico, Mayaguez (Puerto Rico)

Isla de Mona is a carbonate plateau, 50 mi west of Puerto Rico. The plateau is composed mostly of two Miocene carbonate units, the Isla de Mona Dolomite overlain by Lirio Limestone. These two units consist primarily of back-reef sands with a reefal sequence present in the Lirio Limestone to the southwest. The Lirio Limestone is heavily karstified with numerous sinkholes in the central part of the island resembling present-day cenotes of the Yucatan peninsula. Numerous large cave openings are exposed along cliffs surrounding the island, with cavern size rapidly decreasing toward the interior. Within the Isla de Mona Dolomite, three different soil development episodes can be identified in the central part of the island, and on the periphery of the island several episodes of vadose diagenesis are identified by the presence of vadose silts and paleotravertine. Both units exhibit selective dissolution of aragonitic skeletal grains with fabric retentive replacement of former high magnesium calcite skeletal components, by calcite in the Lirio Limestone, and by dolomite in the Isla de Mona Dolomite. Petrographic relationships suggest early diagenetic modification by fluids that were substantially undersaturated with respect to aragonite, which preferentially dissolved aragonitic components, near saturation with respect to calcite/high magnesian calcite during dolomitization, and saturated with respect to calcite during calcitization. Stable isotopic composition of individual dolomitized components and dolomite microspar in the Isla de Mona Dolomite define a hyperbolic trend characteristic of composition produced by fluid mixing. The similarity of the karstified Lirio Limestone to present-day Yucatan, the nature and fluid chemistry requirement of the aragonite dissolution and calcite replacement process, the isotopic composition of the dolomite suggest diagenetic modification under meteoric-marine fluid mixing.

• OSTI ID: 6701828
• Report Number(s): CONF-900605-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:5; Conference: Annual convention and exposition of the American Association of Petroleum Geologists, San Francisco, CA (USA), 3-6 Jun 1990; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CARBONATE ROCKS
DIAGENESIS
CARIBBEAN SEA
PUERTO RICO
CALCITE
DOLOMITE
GEOLOGIC FORMATIONS
LIMESTONE
REEFS
TERTIARY PERIOD
ALKALINE EARTH METAL COMPOUNDS
ATLANTIC OCEAN
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CENOZOIC ERA
FEDERAL REGION II
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GREATER ANTILLES
ISLANDS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
ROCKS
SEAS
SEDIMENTARY ROCKS
SURFACE WATERS
USA
WEST INDIES
580000* - Geosciences