TASMANITE  OIL  SHALE

 

Tasmanites is a long-ranging genus of marine microfossil (see example; see another example).  Tasmanites fossils are organic-walled and tiny (usually <0.1 to ~0.6 mm in size).  Traditionally, their taxonomic affinities have been uncertain, but most researchers now agree that Tasmanites represent cysts of prasinophyte algae (Chlorophyta, Prasinophyceae).

 

Tasmanites is famously abundant in shales of the Lower Permian Quamby Mudstone in Tasmania.  The Tasmanites-rich shales are informally called “white coals”.  Tasmania’s white coals are actually a specific variety of oil shale (kerogen shale/kerogenite) called tasmanite.  They are very rich petroleum source rocks that are not restricted to the Permian of Tasmania.

 

Published research indicates that Permian-aged tasmanite oil shales in Tasmania were deposited in a shallow marine setting dominated by sea ice and/or icebergs, representing a post-glacial sea level rise and flooding of a still-glaciated landscape.

 

Stratigraphy: lower Quamby Mudstone, Lower Parmeener Supergroup, probably Sakmarian Stage, lower Lower Permian.

 

Locality: unrecorded locality at or near the town of Quamby Brook, northern Tasmania.

 

Tasmanite (7.0 cm across at its widest) from the Quamby Mudstone (Lower Permian) of northern Tasmania.

 


 

Tasmanite (~2.1 cm across) from the Quamby Mudstone (Lower Permian) of northern Tasmania.  Each golden-brown structure is a Tasmanites microfossil.  The grayish material is the surrounding mudshale matrix.

 


 

Sample generously donated by the University of Tasmania’s School of Earth Sciences.

 


 

 

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