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Thermal Maturity Patterns (CAI and %Ro) in the Ordovician and Devonian Rocks of the Appalachian Basin in New York State

By David J. Weary, 1 Robert T. Ryder, 1 and Richard Nyahay2

Online Version 1.0


The objective of this study is to enhance existing thermal maturity maps in New York State 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. The thermal maturity of the Ordovician and Devonian rocks is of major interest because they contain the source for most of the unconventional natural gas resources in the basin. Thermal maturity patterns of the Middle Ordovician Trenton Group 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 (Jenden and others, 1993; Ryder and others, 1998). 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, in particular, its basin-centered part (Ryder, 1998). 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 accumulation in Upper Devonian sandstone and Middle to Upper Devonian black shale.

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PDF File of the Report

The PDF file is an Adobe Acrobat file including the text, with figures and tables 1 and 2 of the paper document (see below for obtaining tables 3 and 4). This file, when printed out, will closely resemble the original paper version of this publication. The file size is 4 MB. Adobe Acrobat Reader 3 or later is required to read the report.

PDF file of Open-File Report 00-496.

TABLE3.PDF and TABLE4.PDF are Adobe Acrobat files for printing tables 3 and 4.

TABLE3.XLS and TABLE4.XLS are Microsoft Excel files for tables 3 and 4. This was the native format for compilation of these tables and will enable any user with Microsoft Office or Excel to view, sort, and print the data from those tables.

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Download ArcView Files

The compressed volume (360 KB) contains ArcView data as shapefiles in the arcview_data/ny_cai_files subdirectory, the metadata file (ny_metadata.txt), and an Arcview project file (NY_THERM.APR), which will display the data. All themes are projected to stateplane projection, NAD27 datum. The point and line data are basically a georeferenced subset of that in the tables and figures of the paper. A description of the data is listed in the ENTITY_AND_ATTRIBUTE_INFORMATION section of the metadata.

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1U.S. Geological Survey. 2New York State Geological Survey, Albany, NY 12230.

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U.S. Department of the Interior, U.S. Geological Survey
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Last Modified 02.22.01