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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 55 (1971)

Issue: 2. (February)

First Page: 336

Last Page: 336

Title: Neogene Echinoid Assemblages of Carolinas--Their Paleoecology, Morphologic Adaptations, and Stratigraphic Relations: ABSTRACT

Author(s): Jules R. Dubar, Richard A. Walls, Susan S. Dubar

Article Type: Meeting abstract

Abstract:

Echinoids have considerable potential as stratigraphic and paleoecologic guides for Neogene marine deposits. Entire individuals and fragments are present in most marine units of the Atlantic coastal plain; their calcitic exoskeletons persist where leaching has removed more abundant aragonitic mollusks, and their complexity affords potential for generic and possibly specific classification of disassociated skeletal components.

Exoskeletal size, shape, and thickness; modifications of skeletal plate systems; and the nature of internal structures of skeletal components are environmentally induced morphologic adaptations among individuals of the same species which are potential paleoecologic indicators. The present study indicates that where sedimentation rates are low and the substrate stable, relatively immobile forms are most common, and normally small, active species become large, heavily constructed, and inactive.

Echinoid assemblages studied in detail are from the Waccamaw Formation (Aftonian?) of North and South Carolina, and the Canepatch Formation (Yarmouthian?) of Horry County, South Carolina. Studies of associated biota and sediment characteristics serve as paleoecologic control.

All Waccamaw assemblages are comprised of cassiduloids, clypeasteroids, and arbacoids, whereas only the latter two groups occur in the Canepatch Formation. Populations of the clypeasteroid genera Mellita and Encope are mutually exclusive within the Canepatch Formation.

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