In Geological Society of America, Abstracts with Programs, vol. 35, no. 3, p. 15.


HIGH-RESOLUTION CLIMATIC AND TECTONIC FRAMEWORK FOR THE TRIASSIC-JURASSIC RIFTS OF EASTERN NORTH AMERICA AND MOROCCO AND THE DISTRIBUTION OF POTENTIAL SOURCE ROCKS

OLSEN, Paul E., Lamont-Doherty Earth Observatory, Columbia Univ, 61 RT 9W, Palisades, NY 10964-1000, polsen@ldeo.columbia.edu, KENT, Dennis V., Geological Sciences, Rutgers Univ. and Lamont-Doherty Earth Observatory, Piscataway, NJ 08854, and ET-TOUHAMI, Mohammed, LGVBS, Département des Sciences de la Terre, Université Mohamed Premier, Oujda, Oujda, 60 000, Morocco

With the advent of the Newark basin astronomically calibrated paleomagnetic time scale, it has become at least in principle possible to correlate other sections globally at a much higher degree of precision than possible with most biostratigraphic data. Within the last few years, this possibility has been at least partially realized in North America and Morocco with large portions of the polarity stratigraphy of several basins (spread over a 10° paleolatitudinal latitudinal swath) being worked out and correlated with the Newark basin time scale. In addition a more limited polarity sequence has been worked out in Greenland at about 30° paleolatitude. These correlations demonstrate a strong correspondence between sedimentary facies and latitudinal position as well as with their position within presumed extensional pulses, the stratigraphic consequence of which are the tectonostratigraphic sequences that subdivide the basin sections (TS I – IV).

In eastern North America, significant potential source rocks are restricted to lacustrine strata deposited in very low latitude basins for the Triassic in the early phases of TS-II and TS-III and over a broader latitudinal swath in the Early Jurassic in the early phases of TS-IV. Deposits formed in higher, but still tropical latitudes, include eolian sands, making potentially excellent reservoirs, and evaporites making excellent potential seals and traps (TS-III and TS IV). Good potential source rocks are present in the lacustrine latest Triassic and Early Jurassic of Greenland, deposited in more temperate latitudes.

The temporospacial matrix using these paleolatitude and climatic data make predictions about the stratigraphic and structural location of facies important to the hydrocarbon system. For example, good source rocks are most likely to be present in the buried South Georgia rift, relatively high in TS III for climatic reasons, but these are likely to be gas prone, because the tectonic milieu would favor shallow lakes and coals. Similarly, the only real chance for significant source rocks in the Argana and Fundy basins would be in the deeper and buried parts of the basins in the lower half of TS-II and TS-IV.