7 Sedimentology

Wednesday, 3 April 2002
1:00 PM - 5:00 PM

TELETHERMAL OVERPRINT ON THE PALEOZOIC RECORD OF GLOBAL CHANGE OF CLIMATE AT THE TENNESSEE SOUTHERN APPALACHIANS

Paper number: 7-3
Program: Technical Sessions
Time: 4:00 PM – 4:20 PM

Authors

Abstract

Located within 30° South Latitude, the Southeastern Tennessee Appalachians drifted eastward relative to western South America in the Early and Middle Paleozoic. Then, North America collided with Africa in the Late Paleozoic. Passive margin carbonates were deposited in the Cambrian and in the Early Ordovician. In contrast, foreland basin carbonates were deposited during the Taconian Orogeny in the Middle Ordovician through the Silurian, and in the Acadian Orogeny during the Devonian and Mississippian. Siliciclastics were deposited in the Alleghanian Orogeny.

Carbon isotopic ratios in the Southeastern Tennessee carbonates are consistent with secular variations reported in the literature of the Paleozoic of other regions. Calculated temperatures from oxygen ratios in Cambro-Ordovician carbonates are as high as 53°C, which would be hotter than oceanic temperature in which brachiopods would have lived. Temperatures of Middle Ordovician (30°C - 35°C) and Mississippian carbonates (9°C) are within the range of global variation in these periods. Temperatures calculated from oxygen ratios in chert nodules compared to values in the host carbonate rocks are similar for the Cambro-Ordovician (50°C-59°C), but are higher for the Middle Ordovician (48°C - 58°C) and the Mississippian (41°C). It is interpreted that telethermal solutions were involved during the diagenesis and silicification of the Cambro-Ordovician and during the silicification of the Middle-Ordovician and Mississippian deposits.