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James R. Ebert Damon K. Matteson SUNY College at Oneonta

PRELIMINARY SEQUENCE AND EVENT STRATIGRAPHIC CORRELATIONS WITHIN THE HELDERBERG GROUP (SILURIAN-DEVONIAN) BETWEEN NEW YORK AND THE CENTRAL APPALACHIAN BASIN. James R. Ebert Damon K. Matteson SUNY College at Oneonta. New York: Appalachian Standard Succession.

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James R. Ebert Damon K. Matteson SUNY College at Oneonta

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  1. PRELIMINARY SEQUENCE AND EVENT STRATIGRAPHIC CORRELATIONS WITHIN THE HELDERBERG GROUP (SILURIAN-DEVONIAN) BETWEENNEW YORK AND THE CENTRAL APPALACHIAN BASIN James R. Ebert Damon K. Matteson SUNY College at Oneonta

  2. New York: Appalachian Standard Succession • Late nineteenth and early twentieth century studies • Johnson and Murphy (1969) • Helderberg Group • Silurian-Devonian • Přídolí-Lochkovian • Predominantly limestone • Some shaly units

  3. Primacy of New Yorkin the Early Literature • Early Twentieth Century Stratigraphy and Correlations to New York based on: • General lithologic similarities • Faunal similarities • Names from New York applied from New Jersey to Virginia – the Central Appalachian Basin (CAB)

  4. A New View of Helderberg Stratigraphy • Rickard (1962) - migrating coeval facies • Laporte (1969) – spectrum of ramp environments

  5. Rickard’s Stratigraphy and the Role of the Appalachian Standard Succession • Rickard’s (1962) migrating coeval facies influences correlations • in the CAB • between NY and the CAB • Head (1969, 1972, 1974) • Dorobek (1984), Dorobek and Read (1986)

  6. Revised Helderberg Stratigraphy – New YorkEbert and Matteson (2003a,b)

  7. Rationale for Revised Stratigraphy • Contacts are unconformable • Clarifies placement of the S/D boundary based on conodonts

  8. New Questions in a Classic Setting • How does the presence of unconformities in NY affect correlations within the CAB and between NY and the CAB? • Are these unconformities widespread? Can they be recognized in the CAB and used as a framework for correlation? • What are the relative roles of eustatic and tectonic processes in producing the unconformities? • Can basin-wide revision of Helderberg stratigraphy provide new insights on global sea level change around the S/D boundary?

  9. Framework for Stratigraphic Correlations • Working model of early correlations • Examination of contacts • Evidence of erosion • Evidence of sediment starvation • Biostratigraphic data – FAD Icriodus woschmidti • Unique faunal occurrences - Scyphocrinites • Recognition of events and marker beds • Distinctive facies/lithologies - two • Episodes of siliciclastic influx • Trangressive maxima - two • Bald Hill K-bentonites

  10. Sequence 1: Manlius/Lower Keyser

  11. Sequence 2:Green Vedder/Big Mountain Shale

  12. First Transgressive Maximum and Siliciclastic-bearing Units

  13. Sequence 3: Dayville/U. Manlius/U. Keyser

  14. Sequence 4: Coeymans/New Creek  First Icriodus woschmidti - Silurian/Devonian Boundary HCU is erosional throughout the basin

  15. Sequence 5: Kalkberg/Corriganville 

  16. An Undiscovered Unconformity in NY? ? 

  17. Bald Hill K-bentonites Basin-wide markers (Smith, Berkheiser and Way 1986) Age of S/D Boundary - 418 Ma (Tucker, et. al. 1998)

  18. Second Transgressive Maximum

  19. Conclusions • NY unconformities can be traced into CAB • Most unconformities in NY are erosional • Most in the CAB are marked by sediment starvation • Minelot Falls/Tonoloway-Keyser Unconformity and Howe Cave Unconformity are erosional throughout basin • A Přídolí transgressive maximum is now recognized • Sequence and event stratigraphic correlations between NY and the CAB are similar to those proposed in the early twentieth century • Correlations are preliminary; much more work needs to be done!

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