Site-specific sequence-stratigraphic section benchmark charts are key to regional chronostratigraphic systems tract analysis in growth-faulted basins

Subbasins composing a larger basin can have similar appearing sediment fills that are diachronous. It is important to construct a chronostratigraphic section for each subbasin to correctly correlate between subbasins. A methodology is presented that incorporates the sequence-stratigraphic interpretation of each subbasin, which improves correlation of systems tracts between adjacent and widely separated subbasins. The growth-faulted subbasins in the Corpus Christi Bay area along the western margin of the Gulf of Mexico are used to demonstrate this methodology. A composite wire-line log created by splicing unfaulted and relatively conformable log segments from the deepest wells in an area provides a stratigraphic record that captures a complete succession of depositional and cyclic history. Site-specific sequencestratigraphic section (S) benchmark charts are composite logs containing additional data that summarize available geologic information for a subbasin, site-specific area. Color-coded sequences and component systems tracts are basic information displayed on S benchmark charts. This physical framework can then be calibrated with ages (Ma) of sequences and bounding surfaces. Ages are based on geologic time charts representing latest consensus from isotopic, polarity, and microfossil integration. Sequence-bounding unconformities and internal maximum flooding surfaces delineated on S benchmark charts, when correlated with other wire-line logs and placed into the seismic time domain, produce a chronostratigraphic GEOLOGIC NOTE AAPG Bulletin, v. 89, no. 6 (June 2005), pp. 715–724 715 Copyright #2005. The American Association of Petroleum Geologists. All rights reserved. Manuscript received June 10, 2004; provisional acceptance October 28, 2004; revised manuscript received January 21, 2005; final acceptance January 27, 2005. DOI:10.1306/01270504066 framework for an area. Comparison of S benchmark charts among adjacent, widely spaced, or isolated sites facilitates correlation of diachronous lithostratigraphic units.