Shallow burial dolomitization of Mid-Cenozoic, cool-water, calcitic deep-shelf limestones, southern Australia

Conference · Fri Mar 01 04:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5676977

P, James N ^[1]; Bone, Y ^[2]; Kyser, T K ^[3]

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1. Queen's Univ., Kingston, Ontario (Canada)
2. Univ. of Adelaide (Australia)
3. Univ. of Saskatchewan, Saskatoon (Canada)

Oligocene to middle Miocene, deep-shelf, bryozoan-rich limestones across southern Australia are variably replaced by green to orange, Ca-rich, zoned, medium-crystalline, sucrosic dolomite. The degree of replacement varies from scattered rhombs in limestone to complete dolostones a few tens of meters in thickness and a few kilometers in lateral extent. Dolostone texture ranges from dense and well lithified to completely unlithified, resembling a loose sand of dolomite rhombs. Dolomitization is fabric specific; calcite and Mg-calcite bryozoans are either the last components to be replaced or are molds. The timing and locale of dolomitization are tightly constrained; Sr isotopes indicate a middle to late Miocene age while clasts of dolostone in overlying Pliocene limestones above a regional unconformity confirm a shallow-burial, pre-Pliocene origin. {delta}{sup 13}C and {delta}{sup 18}O values support a marine source for the carbonate; the influence of meteoric fluids appears to have been negligible. Quaternary exposure has resulted in local dedolomitization and/or subaerial erosion, especially in the Murray basin. These rocks are excellent analogues for localized, lenticular dolostone bodies in calcite-rich Paleozoic platform carbonates.

• OSTI ID: 5676977
• Report Number(s): CONF-910403--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 75:3
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
ALKALINE EARTH ISOTOPES
AUSTRALASIA
AUSTRALIA
CALCITE
CARBON 13
CARBON ISOTOPES
CARBONATE MINERALS
CARBONATE ROCKS
CENOZOIC ERA
DEVELOPED COUNTRIES
DIAGENESIS
DOLOMITE
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
GEOLOGIC AGES
ISOTOPE DATING
ISOTOPES
LIGHT NUCLEI
LIMESTONE
MINERALOGY
MINERALS
NUCLEI
OXYGEN 18
OXYGEN ISOTOPES
ROCKS
SEDIMENTARY ROCKS
STABLE ISOTOPES
STRONTIUM ISOTOPES
TERTIARY PERIOD