The Ordovician Earth System
Toward identifying potential causes for stratigraphic change in subtropical to tropical Laurentia during the Mohawkian (early Late Ordovician)
Published:April 01, 2010
Achim D. Herrmann, Bernd J. Haupt, 2010. "Toward identifying potential causes for stratigraphic change in subtropical to tropical Laurentia during the Mohawkian (early Late Ordovician)", The Ordovician Earth System, Stanley C. Finney, William B.N. Berry
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Numerical models of the ocean-climate system indicate that during the early Late Ordovician, water from the higher southern latitudes flowed north toward the equator. The cold-water masses welled up into and penetrated the epicontinental sea of Laurentia. The “cold-water conditions” existed despite high levels of pCO2 (~15× preindustrial atmospheric levels) and did not necessarily indicate the onset of glaciation during the early Late Ordovician; rather the cold-water conditions may indicate the onset of a cooling event that plunged the Ordovician Earth system toward ice-house conditions that would lead later to the end-Ordovician (Hirnantian) glaciation. Furthermore, the observed distribution of cold-water masses across the southeastern margin of Laurentia is consistent with the interpretation that a cold-water event caused a regional extinction in the Mohawkian of eastern Laurentia.