Title

Graphic Correlation of the Pennsylvanian-Lower Permian Strata in Spitsbergen and Loppa High, Barents Sea: Independent Tool for Testing Regional Sequence Stratigraphic Models

Publication Date

5-2001

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Geology

Department

Geosciences

Major Advisor

Vladimir I. Davydov

Abstract

Graphic Correlation (GC) is a quantitative-qualitative technique that examines the stratigraphic record with a degree of detail not attainable by conventional biostratigraphic methods. Traditional biostratigraphy estimates the completeness of the stratigraphic record based on the presence or absence of zonal units of a standard biostratigraphic scale. In contrast, GC uses first and last occurrences of all relevant taxa throughout the section. The composite standard section utilizes data from all study localities in order to build an idealized uninterrupted succession of biostratigraphic events. The composite section, calibrated with radiometric dates, serves as a chronostratigraphic scale to which all other data are compared. This approach allows the identification of hiatuses in the sedimentary record within zones. GC enables precise dating of sequences and helps to recognize subtle unconformities. GC also can be used to estimate the duration of hiatuses as short as circa 0.5 Ma and provides a mechanism to tie these results into regional and interregional stratigraphic frameworks with a high degree of confidence.

The Pennsylvanian-Lower Permian (upper Moscovian-lower Sakmarian) predominantly carbonate platform successions of Spitsbergen and the Barents Shelf contain diverse and well-preserved fusulinacean faunas. The fusulinid assemblages occurring in these areas belong to the Boreal paleobiogeographic province and provide ideal material for establishing and refining a chronostratigraphic framework for the Arctic Region. GC was applied to biostratigraphic data from the central Spitsbergen outcrops and Barents Sea subsurface: the Finnmark Platform and Loppa High. The created Arctic Composite Section contains about 1000 fusulinid taxa. It provides a robust basis for regional correlation and serves as an independent means of testing and improving the recently established sequence stratigraphic models for the Barents Shelf.

In central Spitsbergen, six depositional sequences separated by major hiatuses have been identified by utilizing GC. The individual sequences comprise several fusulinid zones or only some part of a single zone and represent time intervals from a few hundred Ka to more than 2 Ma. These sequences are separated by hiatuses ranging from 0.4 Ma to more than 4.0 Ma in duration. There is striking similarity between time-frames of the identified sequences and bounding hiatuses even in areas where local tectonism was important. Correlation in the Barents Shelf region suggests that eustasy exerted a major control on the sequence formation despite active tectonic setting at some localities. Preliminary interregional correlation suggests that some sequences and bounding hiatuses are eustatic in nature because they occur throughout the Northern Pangaea.

One common practice in sequence stratigraphic models equates sequence boundaries to stage and system boundaries. This study suggests continuous stratigraphic record across the Carboniferous-Permian boundary interval in the Arctic region. Also, the stratigraphic record is apparently continuous across the Asselian-Sakmarian boundary indicating a latest Asselian age for the widely recognized early Sakmarian "Tastubian" glacio-eustatic transgression of Veevers and Powell (1987). The Arctic data and preliminary interregional correlation suggest that the Pennsylvanian-Lower Permian global cycle chart of Ross and Ross (1987) needs at least partial revision.

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