Analysis Number
1508007
Petrology Number
1933064
Historical Petrology Number
Analyst
Petrology Analysis Date
Thin Section in Storage
Y
Petrology Specimen Type
Thin Section
Lithology
Limestone
Summary Decription
Heterogeneous grey compact micritic limestone, with fossil fragments in calcite-rich areas, also irregular lenses of dolomite with fractures and small voids and lenses of coarse sparry white calcite and a lenticular calcite vein.
Detailed Decription
Rock type from TS Heterogeneous grey compact micritic limestone, with fossil fragments in calcite-rich areas, also irregular lenses of dolomite with fractures and small voids and lenses of coarse sparry white calcite and a lenticular calcite vein.
Hand specimen Grey limestone with pale yellow-brown masses of dolomite
PETROGRAPHY
Visually estimated mineralogy:
Mineral Abundance Origin/location
Fossils and fossil fragments Minor Possibly detrital fossils?
Micritic and microsparry calcite Dominant in some areas Possible fossil fragments and matrix
Lenses of fine-grained dolomite with limonite and clay Minor/common (15-20%) Secondary dolomite lenses with minor porosity and fractures
Lenses of coarse-grained calcite Minor/common Mostly in and adjacent to dolomite lenses
This sample is very heterogeneous with irregular pale yellow-brown masses of dolomite (as indicated by staining on the cut face of the hand specimen) as well as more abundant calcite. The overall carbonate composition (Ca87.8Mg11.4Fe0.8) seems to indicate dolomite as well as calcite.
The calcite-rich areas are also heterogeneous, locally incorporating apparent fossil fragments to 4mm long composed variously of microcrystalline and microsparry calcite. Large areas have possible fossil fragments to 0.5mm long and sparse dolomite rhombs in microcrystalline calcite.
Mineral Abundances by Volume
Abundant > 70%
Major 30-70%
Minor 5-29%
Dolomite
Trace 1-4%
Calcite, Clay mineral, Limonite
Rare <1%
Unknown abundance
Rock Sample Petrology information pending.