Chronostratigraphy of Cenozoic Depositional Sequences and Systems Tracts: A Wheeler Chart

RI0273. Chronostratigraphy of Cenozoic Depositional Sequences and Systems Tracts: A Wheeler Chart of the Northwest Margin of the Gulf of Mexico Basin, by L. F. Brown Jr. and R. G. Loucks. 28-p. text, 1 oversized color chart, 2009. Print.

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ABSTRACT
A chronostratigraphic chart (Wheeler chart) was constructed of the Cenozoic strata of the northwest margin of the Gulf of Mexico basin (Texas coastal area). This sequence stratigraphic framework divides outcrop and subsurface lithostratigraphic units (members, formations, and groups) into 50 chronostratigraphic (sequence) and lithogenetic (depositional systems) packages. The framework links the outcrop with the more extensive subsurface stratigraphy. The diagrammatic paleoslope systems-tract profiles provide the subsurface geologist with an inferred but integrated view of the depositional elements that define each principal siliciclastic impulse of sediment delivered into the basin. Although absolute ages on the chronostratigraphic chart are equivocal, they do place the sedimentary record into a logical outcrop-to-deep-basin relative perspective.

The chronostratigraphic chart was constructed for the benefit of not only subsurface petroleum geoscientists, but also academic and other researchers working on outcrop stratigraphy, sedimentology, paleontology, and petrography. This nonproprietary chronographic chart ought to encourage Gulf Coast geoscientists either to modify the chart with their own proprietary data or release their own proprietary chronostratigraphic documents. Through further enhancement of the Wheeler chart, a deeper understanding of the architecture and depositional history of the Gulf of Mexico can be achieved, thus leading to a more complete understanding of the petroleum systems of the Gulf of Mexico.

Keywords: Cenozoic, chronostratigraphy, depositional sequences, Gulf of Mexico basin, sequence stratigraphy, system tracts, Tertiary, Wheeler chart

CONTENTS

Abstract

Introduction

Concept of a Cenozoic Sequence Stratigraphic Chart

Geochronology vs. Chronostratigraphy vs. Lithostratigraphy

Wheeler Diagrams

Sources of Data Used to Prepare Wheeler Chart
            Lithostratigraphy, Nomenclature, and Literature Sources
            Subsurface Geology
            Micropaleontology
            Ages (Ma) of Sequence Stratigraphic Surfaces

Methodology

Key Aspects of Graphic Presentation of Sequence Stratigraphy Displayed on Chronostratigraphic Chart
            Legend
            Characterization of Stratal Units (Parasequence Sets
            Frequencies of Sequences and Systems Tracts
            Coastal and Slope (Marine) Onlap

 Sequences and Sequence Boundaries: Key Sequence Surfaces

             Type-1 Unconformity = Type-1 Sequence Boundary
             Type-2 Unconformity = Type-2 Sequence Boundary
             Incised-Valley Erosion (iv) Surface
             Transgressive (Ravinement Erosion) Surface (TS)
             Marine Condensed Sections (mcs = mfs)

 Sequence Stratigraphic Systems Tract Components
             Depositional Systems
                  Lowstand Depositional Systems Tracts (LST’s)
                      Incised-Valley-Fill (ivf) Systems
                  Basin-Floor Fans and Channel-Fill (bff) Systems
                      Slope-Fan Systems (sf’s)
                  Prograding Deltaic Wedge (pw) or Prograding Complex Systems
                      On-Shelf Type-1 Lowstand (Shelf/Ramp) Systems Tracts
                      Transgressive Systems Tracts (TST’s)
                      Highstand Systems Tracts (HST’s)
 
Relationship of Hydrocarbon Systems and Sequence Stratigraphy

Sequences and Systems Tracts of the Texas Gulf of Mexico Basin Margin
               Tertiary Paleocene Series—Midway Group
                     Sequence 1 (66.5–64.05 Ma): Kincaid Formation
                     Sequence 2 and Lower Part of Sequence 3 (64.05–59.2 Ma): Wills Formation
               Tertiary Paleocene-Eocene Series—Wilcox Group
                     Upper Part of Sequence 3 (60.9–59.2 Ma): Hooper Member of the Seguin Formation
                     Sequence 4 (58.5–54.9 Ma): Solomon Creek, Caldwell Knob, Butler, and   Simsboro Members of the Seguin Formation and Lower Part of the Rockdale Formation
                     Sequence 5 (54.9–49.5 Ma): Calvert Bluff Member, Sabinetown Formation, and Lower Part of Carrizo Formation

               Tertiary Eocene Series—Claiborne Group
                     Sequence 6 (49.5–48.5 Ma): Carrizo Lowstand, Unnamed TST and HST
                     Sequence 7 (48.5–46.5 Ma): Reklaw and Queen City Formations
                     Sequence 8 (46.5–43.6 Ma): Weches and Sparta Formations
                     Sequence 9 (43.6–40.0 Ma): Cook Mountain and Yegua Formations

                 Tertiary Eocene Series—Jackson Group
                     Sequence 10 (40.0–36.6 Ma) Moodys Branch TST and Lower Jackson Group HST
                     Lower Part of Sequence 11 (36.6–33.47 Ma) Upper Jackson (TST)

                 Tertiary Oligocene Series—Vicksburg Group
                     Upper Part of Sequence 11 (33.47–32.5 Ma): Vicksburg HST

                Tertiary Oligocene Series—Catahoula Group

                      Sequence 12 (32.5–30.7 Ma): Unnamed TST, Catahoula, and Basal Frio Cycle 1
                      Sequences 13–18 (30.7–24.1 Ma): Frio Cycle 2– Cycle 6 and Anahuac Shale Mbr

                 Tertiary Miocene Series—Fleming Group
                      Sequences 19–Lower Part of 23 (24.1–16.3 Ma): Oakville Formation
                      Sequences 23 (Upper Part) through 31 (16.3–5.65 Ma): Lagarto Formation

                 Tertiary Pliocene Series—Citronelle Group
                      Sequences 32–38 (5.65–3.04 Ma): Goliad Formation
                      Sequences 39–42 (3.04–1.72 Ma): Willis Formation

                 Quaternary System—Pleistocene-Holocene Series—Houston Group
                      Sequences 43–49 (1.7–0.001 Ma): Lissie, Montgomery, Beaumont Formations
                      Sequence 50 (1.01–0.0 Ma): Holocene (TST)

Conclusions

Acknowledgments

References

Appendix A: Glossary of Sequence and Depositional Systems Terms

Appendix B: Representation of Various Geochronologic Units or Divisions and Their Contained Rock Successions


Citation
Brown, L. F., Jr., and Loucks, R. G., 2009, Chronostratigraphy of Cenozoic Depositional Sequences and Systems Tracts: A Wheeler Chart of the Northwest Margin of the Gulf of Mexico Basin: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations No. 273, 28 p., 1 chart.