Contact metamorphosed Limestone
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Fact sheet
Description: 

This sample of impure marble was caused by the thermal metamorphism of Lower Jurassic (Broadford Beds) limestone at Allt nam Ba on the Isle of Rum, Scotland.  The elongate areas are almost certainly metamorphosed bivalves; and less-altered rocks from this area yield a sparse Lower Jurassic fauna.

The thin section appears to confirm the fosilliferous nature with several bivalve shaped areas of calcite. Some of the calcite-rich areas have recrystallised, exhibiting equilibrium (60 degree) grain boundaries, while other areas appear to exhibit structures closer to the original structure and grainsizes. A fine grained cement between the pure calcite areas was probably micritic in the original limestone.

In Place
In Time
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Accuracy:
Location precision: 
Good
Timescale:
Timescale: 
Paleogene
Ma = Millions of years ago
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Type: 
metamorphic
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