Rock & Mineral MacroGigaPans > Snowball Earth Educational Rock Sample Suite PFH-1 by Robin Rohrback-Schiavone

From the Amogjar cap dolostone in West Africa.

This barite fan records barium sulfate remobilization that occurred during a rapid shift in oceanic chemical conditions. Barium sulfate is insoluble in oxygenated water, but under anoxic conditions it will dissolve in the manner seen here. PFH-1 records unusual oceanic chemical conditions and a short-lived chemical disturbance.

In terms of a Snowball Earth, barite mineral fans like this one are believed to have formed during the rapid deglaciation and hothouse aftermath of a Snowball event. PFH-1 is interpreted as having been deposited as anoxic oceans, created by ice cover that prevented mixing between the atmosphere and ocean water, once again became oxygenated with the resumption of the hydrologic cycle in the aftermath of a Snowball event.

Sample is 7.8 cm across at its widest point.

This sample is from the Snowball Earth Educational Rock Sample Suite, and comes courtesy of Paul Hoffman, Harvard University; Eugene Domack, Hamilton College; and Timothy Fox, Hamilton College.
For more information on the Snowball Earth Educational Rock Sample Suite, visit www.snowballearth.org/samples.html .
Image made as part of the MAGIC project (Mid-Atlantic Geo-Imagery Collection) using Northern Virginia Community College's gigamacro rig, as seen here:
gigamacro.com/gigapixel-macro-imaging-system /