By: magic-gigapans
Image: Robin Rohrback, Mid-Atlantic Geo-Image Collection
License: Creative Commons Non Commercial ⧉

Uploaded: 4 May 2020
Last Updated: 26 Jun 2020

337 megapixels
18,408 x 18,332 pixels
61.4 in X 61.1 in at 300dpi
4,043 pixels per inch

Pseudomorphosed aragonite crystal fans in calcimicrite from the Hayhook Formation. PFH-3 is an aragonite crystal fan from the Mackenzie Mountains in northwest Canada. The aragonite has been partially replaced by dolomite and calcite minerals. The sample records several intervals of fan growth and truncation, and is interpreted as having been deposited during a period of short-lived, unusual climatic conditions during the rapid deglaciation and warming of calcium carbonate-saturated waters at the end of a Snowball event. According to the Snowball Earth hypothesis, these super-saturated conditions are the compound result of cold ocean waters (cold favors higher CaCO3 solubility) created during glaciations, and increased CaCO3 weathering of terrestrial rocks with the resumption of the hydrologic cycle during the rapid shift from icehouse to greenhouse conditions. Sample is 8 cm long. 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 http://www.snowballearth.org/samples.html