Link to USGS home page.
U.S. Geological Survey Open-File Report 2005-1078

Thermal Maturity Patterns (CAI and %Ro) in the Ordovician and Devonian Rocks of the Appalachian Basin in West Virginia

Published 2005

By John E. Repetski, 1 Robert T. Ryder, 1 Katharine Lee Avary, 2 and Michael H. Trippi1


The objective of this study is to enhance existing thermal maturity maps in West Virginia by establishing: 1) new subsurface CAI data points for the Ordovician and Devonian and 2) new %Ro and Rock Eval subsurface data points for Middle and Upper Devonian black shale units. Thermal maturity values for the Ordovician and Devonian strata are of major interest because they contain the source rocks for most of the oil and natural gas resources in the basin. Thermal maturity patterns of the Middle Ordovician Trenton Limestone are evaluated here because they closely approximate those of the overlying Ordovician Utica Shale that is believed to be the source rock for the regional oil and gas accumulation in Lower Silurian sandstones (Ryder and others, 1998) and for natural gas fields in fractured dolomite reservoirs of the Ordovician Black River-Trenton Limestones. Improved CAI-based thermal maturity maps of the Ordovician are important to identify areas of optimum gas generation from the Utica Shale and to provide constraints for interpreting the origin of oil and gas in the Lower Silurian regional accumulation and Ordovician Black River-Trenton fields. Thermal maturity maps of the Devonian will better constrain burial history-petroleum generation models of the Utica Shale, as well as place limitations on the origin of regional oil and gas accumulations in Upper Devonian sandstone and Middle to Upper Devonian black shale.

PDF File of the Report

The PDF file below is an Adobe Acrobat file including the text, figures, and tables of the paper document. This file, when printed out, will closely resemble the original paper version of this publication. The file size is 2.5 MB. Adobe Reader is required to read the report.

Open-File Report 2005-1078 [2.5 MB]
Open-File Report 2005-1078 (This version is Section 508 compliant) [5 MB]


Table 1 and table 2 are Microsoft Word files for tables 1 and 2. This was the native format for compilation of these tables and will enable any user with Microsoft Office or Word to view and print the data from those tables.

Table 3 is a Microsoft Excel file for table 3. This was the native format for compilation of this table and will enable any user with Microsoft Office or Excel to view, sort, and print the data from this table.

Get Adobe Reader


For scientific questions or comments concerning this report, contact Michael Trippi.

Ordering U.S. Geological Survey Products: call toll-free (from the U.S.) 1-888-ASK-USGS, or e-mail

1U.S. Geological Survey. 2West Virginia Geological Survey, Morgantown, WV 26507.

FirstGov button  Take Pride in America button