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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 51 (1967)

Issue: 3. (March)

First Page: 460

Last Page: 460

Title: Palynomorphs as Indicators of Nearshore and Offshore Features in Modern Sedimentary Basins: ABSTRACT

Author(s): Aureal T. Cross

Article Type: Meeting abstract

Abstract:

Distribution of pollen, spores, cuticles, tracheids, as well as dinoflagellates, hystrichospheres, microforaminifers, and certain other microplankton, may be used within certain limitations to identify or assist in determining sedimentary environments and ancient paleogeographic patterns.

Special consideration is given to the modifying influence of marine circulation, currents, tides, etc. on patterns of distribution. Configuration and restrictions of basin and shorelines, patterns of surface or near-surface circulation resulting from prevailing wind regimes (resulting in localized areas of upwelling in different seasons), submarine canyons, and other such agencies and features cause significant modifications on distribution patterns of palynomorphs.

Direction, strength, and season of prevailing winds and storms exert some control in distribution of pollen and spores. Down-wind distribution areas show decreasing frequency from source areas.

Dilution of palynomorph concentrations in the vicinity of deltas and channels, where an abundant supply of terrigenous sediments is accumulating, seems to lower absolute frequencies of palynomorphs only in main channels and very near the shore.

Differential susceptibility to decay, which characterizes these entities, makes it difficult to depend on the presence or absence of particular pollen of plants which make up the communities on the coastal plains to identify nearshore position.

Use of total number of spores and pollen in sediments, to determine positions of former shorelines, should be amplified with a consideration of type of sediment at the sampling site and the nature of thanatocoenoses of marine faunas and algae.

Cuticles and tracheids are extremely abundant in fine sediments near the shore and decrease offshore. Cuticular fragments greater than 1 millimeter in diameter usually are not carried or are destroyed within a few miles of shore; tracheids greater than 50ยต and finer cuticles are deposited in decreasing numbers 50-100 miles offshore.

Some kinds of palynomorphs increase in relative frequency, compared with total pollen and spores, with increasing distance offshore. Mangrove and pine are typical of this group. Herbaceous pollen generally is more abundant near the shore.

Comparison is made of results of studies of palynomorphs in modern bottom sediments in the Gulf of California, Gulf of Paria, Mediterranean Sea, Sea of Okhotsk, and Gulf of Mexico for the purpose of indicating proximity to shorelines and deltas.

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Copyright 1997 American Association of Petroleum Geologists