Premium
Textural and geochemical alternations in Late Cenozoic Bahamian dolomites
Author(s) -
DAWANS JOHN M.,
SWART PETER K.
Publication year - 1988
Publication title -
sedimentology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.494
H-Index - 108
eISSN - 1365-3091
pISSN - 0037-0746
DOI - 10.1111/j.1365-3091.1988.tb00993.x
Subject(s) - geology , diagenesis , sedimentary depositional environment , dolomite , geochemistry , facies , strontium , mineralogy , cenozoic , petrography , paleontology , physics , structural basin , nuclear physics
Dolomitized intervals of a core from San Salvador Island, Bahamas, exhibit variations of two texturally and geochemically distinct end‐members. In the Pliocene section of the dolomitized interval, the two end‐members alternate in a pattern that may reflect originally and/or diagenetically modified depositional facies. Formerly mud‐free intervals, locally capped by exposure surfaces are massive crystalline, mimetic dolomites (CM). Muddier sediments are replaced by friable microsucrosic dolomites (MS). CM and MS dolomites also differ in porosity (< 10% vs > 30%), permeability (< 10 md vs > 100 md), mol% MgCO 3 (44–9 vs 47–7) mol%), oxygen isotopic composition (1–7 vs 2–7‰) and strontium content (241 vs 106 ppm). These data indicate that depositional and diagenetic fabric are the principal controls governing the distribution of dolomite types. Differences in texture and geochemistry are suggested as arising through differential rates of crystallization produced as a result of variations in permeability and reactivity of the precursor sediments and rocks.