Mesozoic sedimentation on the eastern Falkland Plateau

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doi: 10.2973/dsdp.proc.36.122.1977
Author(s): Thompson, R. W.
Author Affiliation(s): Primary:
Humboldt State Univ., Sch. Nat. Resour.-Oceanogr., Arcata, Calif., United States
Volume Title: Initial Reports of the Deep Sea Drilling Project
Source: Initial Reports of the Deep Sea Drilling Project, Vol.36, p.877-891. Publisher: Texas A & M University, Ocean Drilling Program, College Station, TX, United States. ISSN: 0080-8334 CODEN: IDSDA6
Note: In English. 27 refs.; illus. incl. tables, sketch maps
Summary: Mesozoic sediments were encountered in two borings on the Falkland Plateau. At Hole 327A, calcareous ooze of Late Cretaceous (Maestrichtian) age was first encountered at a subbottom depth of 90 m and the hole was terminated in carbonaceous claystones of Early Cretaceous (Neocomian-Aptian) age at a subbottom depth of 470 m. At Site 330, calcareous (nanno) clay of Albian age was first cored at a subbottom depth of 129 m and thereafter Mesozoic sediments ranging back to at least Upper Jurassic (Oxfordian) were drilled to a total depth of 550 m. Below these a probable old soil profile and underlying basement rocks of granulitic gneiss and granite pegmatite were encountered. The Mesozoic sequences penetrated at these two sites suggest a depositional history as follows: 1) subaerial (paralic?) sedimentation resulting in infill and aggradation of local bedrock basins; 2) Middle (?) to Upper Jurassic marine transgression followed by accumulation of predominantly terrigenous silts and clays in an open-shelf environment; 3) euxinic conditions and deposition of dark carbonaceous claystones which began in Upper Jurassic and persisted until near the end of the Lower Cretaceous (late Aptian); 4) open marine deposition of pelagic carbonate oozes and zeolitic clays through the remainder of the Mesozoic and most of the Tertiary. This discussion summarizes the characteristics of the Jurassic and Lower Cretaceous sediments encountered at these two sites and their interpretation in terms of depositional environments and geologic events.
Year of Publication: 1977
Research Program: DSDP Deep Sea Drilling Project
Key Words: 06 Petrology, Sedimentary; Atlantic Ocean; Clastic sediments; Cretaceous; DSDP Site 327; DSDP Site 330; Deep Sea Drilling Project; Deposition; Environment; Falkland Plateau; Jurassic; Leg 36; Lower Cretaceous; Marine environment; Mesozoic; Nonterrigenous materials; Sedimentary petrology; Sedimentation; Sediments; South Atlantic; Terrigenous materials; Upper Jurassic
Coordinates: S505500 S505200 W0464700 W0465300
Record ID: 1977040615
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from the Antarctic Bibliography, United States