Similarities in the dolomitization of upper Miocene reef complexes in Mallorca and the Las Negras areas, Spain: Possible evidence for a Mediterranean dolomitizing event during the Messinian

Conference · Fri Mar 01 00:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:7259816

Oswald, E J; Meyers, W J ^[1]; Franseen, E K ^[2]

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1. SUNY, Stony Brook, NY (United States)
2. Univ. of Kansas, Lawrence (United States)

Reef complexes in the Las Negras area and the island of Mallorca, over 600 km to the northeast, contain dolomite with remarkably similar stratigraphic distribution and petrographic characteristics. In both reef complexes dolomite occurs as 5-50 {mu}m euhedral cements and microcrystalline replacement of red-algal fragments and muds. In addition, anhedral, moldic-zoned dolomite cements (5-20 {mu}m) are abundant in the youngest reefs of both areas. All inter-reefal erosional surfaces are cross-cut by dolomite cements. Distribution of dolomite within the reefal sequences is controlled by (1) proximity to the youngest reef margin. Dolomite abundances decrease from 100% to 0% over a 10 km transect into the platform interior in Mallorca. Stratigraphic and petrographic timing support a dolomitization event following exposure of the reefs, during initial deposition of the onlapping Messinian sequence in Mallorca, and before Pliocene deposition in Las Negras. In both areas, dolomitization took place as a Messinian transgression covered the reefs. Evidence for multiple dolomitization events has not been found. Mallorcan dolomites have heavy stable isotopes suggesting saline dolomitizing fluids. One hypothesis for dolomitization invokes brines associated with the deposition of extensive Messinian basinal evaporites. An early Messinian evaporitic lowstand could concentrate marine brines, and with the ensuing transgression bring them in contact with CaCo{sub 3} platforms, dolomitizing them. The similar styles and timing of dolomitization in these two distinct and distant reef settings suggest that dolomitization of late Miocene reefs around the western Mediterranean may have been genetically related to the Messinian salinity crisis.

• OSTI ID: 7259816
• Report Number(s): CONF-910403-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 75:3; Conference: Annual meeting of the American Association of Petroleum Geologists (AAPG), Dallas, TX (United States), 7-10 Apr 1991; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
BRINES
ROCK-FLUID INTERACTIONS
CARBONATE ROCKS
DIAGENESIS
PETROLOGY
SPAIN
GEOLOGIC DEPOSITS
CHEMICAL COMPOSITION
COMPARATIVE EVALUATIONS
CRYSTALLOGRAPHY
DOLOMITE
EVAPORITES
GEOCHEMISTRY
GEOLOGIC HISTORY
MEDITERRANEAN SEA
MINERALOGY
MIOCENE EPOCH
REEFS
CARBONATE MINERALS
CENOZOIC ERA
CHEMISTRY
DEVELOPING COUNTRIES
EUROPE
EVALUATION
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GEOLOGY
MINERALS
ROCKS
SEAS
SEDIMENTARY ROCKS
SURFACE WATERS
TERTIARY PERIOD
580000* - Geosciences