About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 63 (1979)

Issue: 3. (March)

First Page: 507

Last Page: 508

Title: Atmospheric Circulation and Upwelling in Paleozoic, with Reference to Petroleum Source Beds: ABSTRACT

Author(s): Judith Totman Parrish, Kirk S. Hansen, Alfred M. Ziegler

Article Type: Meeting abstract


Liquid hydrocarbons are formed from phytoplankton deposited in marine sediments. Phytoplankton are not distributed uniformly throughout the ocean surface waters. They are sparse over most of the area of the ocean, but are abundant in zones of upwelling where water rich in nutrients is brought to the lighted surface waters. Locations of these organically productive upwelling zones in the past can be predicted using a combination of paleogeographic and paleo-oceanographic modeling. This provides valuable information on likely times and geographic areas in which oil source beds were deposited.

Upwelling is caused by steady, prevailing winds resulting in divergence of currents or the movement of currents away from landmasses. These winds are parts of major atmospheric circulation systems. Their characteristics depend on latitude, season, and the sizes and positions of oceans and continents, but have a physical basis. They can, therefore, be modeled for past continental configurations, and it follows that upwelling can also be predicted.

Atmospheric circulation and upwelling maps for seven stages in the Paleozoic, using new paleogeographic reconstructions, show that upwelling zones of each stage are related to regions with source beds of that age. Although upwelling does not automatically result in source beds and all source beds do not occur in ancient

End_Page 507------------------------------

upwelling zones, knowing the past areas of upwelling and abundant phytoplankton productivity is vital for assessing the potential richness and extent of possible oil source beds.

End_of_Article - Last_Page 508------------

Copyright 1997 American Association of Petroleum Geologists