Fecal Pellets in Spar Cement - Jurassic (Pel/10/Jur/Eng)
10x
|
10x
|
2.5x
|
2.5x
|
5x
|
5x
|
5x cross nicol
|
Outstanding feature |
Elongated Fecal Pellets in a Matrix of Calcite Cement. Few Fossils. |
Folk Classification |
PelSparite |
Dunham Classification |
Pelgrainstone |
Common Grains |
Fecal Pellets with sparse pelecypod valves |
Sorting |
Well sorted |
Rounding |
Well rounded |
Micritization & envelopes |
Slight alteration of margins of bioclasts |
Cement & diagenetic fabric |
Calcite |
Porosity |
|
Depositional Setting |
Low energy |
Diagenetic history |
Pellets hardened at excretion and cemented during burial. |
This is a typical fecal pellet carbonate that accumulated in a low energy probably restricted setting, since there seem to be few bioclasts. Note the lack of interpenetration supporting the interpretation that these grains hardened shortly after they were excreted. The setting of these sediments appears to have ranged from marine, to evaporitic to fresh water on the basis of the sedimentary association with the Purbeck Formation and Fossil Forest.
Thursday, November 11, 2021