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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 67 (1983)

Issue: 9. (September)

First Page: 1464

Last Page: 1464

Title: Cretaceous and Tertiary Samples Dredged from Florida Escarpment, Eastern Gulf of Mexico: ABSTRACT

Author(s): R. P. Freeman-Lynde

Article Type: Meeting abstract


Cretaceous and Tertiary rocks were dredged along the Florida Escarpment at five areas south of 27°05^primeN in late 1982 during cruise LY-82A of USNS Lynch. The escarpment was sampled from near the base (as deep as 3,300 m, 10,800 ft) to near the top (as shallow as 1,500 m, 4,900 ft) of the slope. The majority of samples recovered are middle Cretaceous peritidal and lagoonal limestones and dolomites deposited under restricted, low-energy conditions. Presumed middle Cretaceous dolomites deposited in hypersaline bank-interior environments were taken primarily from the walls of canyons incised from 10 to 50 km (6 to 30 mi) into the escarpment, and also from the escarpment proper at several dredge stations. Limestone lithologic characteristics are generally bioturbated m liolid and mollusk wackestone/packstone (lagoonal) and fenestral and algal-laminated mudstone/wackestone (peritidal). Some dolomites retain primary sedimentary structures (e.g., mottling and algal lamination), whereas others appear structureless, perhaps due to recrystallization. Few of the middle Cretaceous samples were deposited under high-energy conditions. Those that are high-energy deposits are bioclastic rudstones and coral boundstones. Late Cretaceous and Tertiary deep-water limestones and chalks unconformably overlie and drape the older shallow-water carbonates. The limestones are Late Cretaceous in age, while the chalks range from Late Cretaceous through Pleistocene. The limited occurrence of high-energy facies rocks indicates that the escarpment has been eroded bankward over it entire length south of 27°05^primeN, and not just at canyon reentrants. The younger deep-water rocks reflect the drowning of the middle Cretaceous platform in Late Cretaceous time. The facies change from limestone to dolomite is attributed to higher salinities in the bank interior during the middle Cretaceous.

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