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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 5. (May)

First Page: 927

Last Page: 927

Title: Comparison of Middle Eocene Sporomorph Assemblages from Southern California and Gulf Coast: ABSTRACT

Author(s): Norman O. Frederiksen

Article Type: Meeting abstract


Fifteen samples from the Delmar Formation and Ardath Shale (lower middle Eocene) and six from the Mission Valley Formation (middle or upper part of the middle Eocene) of San Diego contain about 180 sporomorph (pollen and spore) taxa. The high diversities of Pinaceae-Podocarpaceae, Ephedra-Ephedripites, Palmae, Onagraceae, Bombacaceae-Sterculiaceae-Tiliaceae, and perhaps Euphorbiaceae are similar to those of the modern flora of the region. The flora apparently represents a warmer climate than does the coeval flora of the Gulf Coast. The Eocene flora of San Diego only moderately resembles the present flora of southern California and northwestern Mexico--for example, Fagaceae (oaks, etc) are very rare or absent; this suggests a different climate from that of the present (pro ably more moist and perhaps summerwet rather than summer-dry).

In contrast, the middle and upper Eocene assemblages of the Gulf Coast are rich in Fagaceae pollen; these assemblages suggest that the Eocene climate was somewhat warmer but otherwise rather like the present climate of this region.

Relatively few sporomorph taxa are common to the middle Eocene of southern California and the Gulf Coast. Sporomorph correlations between the two regions are also difficult at present because the ranges of the San Diego taxa are unknown above or below the middle Eocene in southern California. Nevertheless, Milfordia hungarica and Yeguapollis may prove to be useful for correlating the middle Eocene from southern California with the palynologically better known Gulf Coast units.

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