Mesozoic-Cenozoic sedimentary formations of the North American Basin; western North Atlantic

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doi: 10.1029/ME003p0001
Author(s): Jansa, L. F.; Enos, P.; Tucholke, B. E.; Gradstein, F. M.; Sheridan, R. E.
Author Affiliation(s): Primary:
State Univ. N.Y., Binghamton, N.Y., United States
Volume Title: Deep drilling results in the Atlantic Ocean; continental margins and paleoenvironment
Volume Author(s): Talwani, M., editor; Hay, W.; Ryan, W. B. F.
Source: Maurice Ewing Series, 3, p.1-57; Deep drilling results in the Atlantic Ocean; continental margins and paleoenvironment, Harriman, N.Y., March 19-25, 1978, edited by M. Talwani, W. Hay and W. B. F. Ryan. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0197-6346. ISBN: 978-1-118-66583-1 CODEN: MEWSDN
Note: In English. 130 refs.; illus. incl. tables, strat. cols., sects., plates, geol. sketch maps
Summary: Deep Sea Drilling Project sites in the North American Basin penetrated Mesozoic and Cenozoic sedimentary sequences of similar lithology, age, faunal assemblages and petrographic composition, permitting the definition of six formations. These are in ascending order: the Cat Gap Formation (Oxfordian-Tithonian grey-green limestone, reddish-brown argillaceous limestone, and calcareous claystone); the Blake-Bahama Formation (Tithonian-Barremian light grey limestone and chalk); the Hatteras Formation (Barremian-Cenomanian black and green-grey shale and claystone); the Plantagenet Formation (Late Cenomanian to ?Early Eocene varicolored zeolitic clay); the Bermuda Rise Formation (Paleocene to Middle Eocene chert and siliceous ooze); and the Blake Ridge Formation (Eocene to Holocene hemipelagic grey-green mud with local mass-flow deposits). In addition, the Crescent Peaks Member (Maastrichtian nannofossil marl) of the Plantagenet Formation and the Great Abaco Member (Miocene mass-flow deposits) of the Blake Ridge Formation are defined. The Cat Gap, Blake-Bahama, and Bermuda Rise Formations and the Crescent Peaks and Great Abaco Members are seismically mappable, with the formation boundaries approximately corresponding to major seismic reflectors (C, β, AC , A*, M, respectively) in the western North Atlantic. The oldest sedimentary rocks recovered by DSDP in the North American Basin are red or grey-green argillaceous limestones at Sites 99, 100 and 105, which are not older than Oxfordian. These sediments were deposited in a deep bathyal environment, near but above the calcite compensation depth (CCD). Pelagic carbonate deposition above the CCD continued into the Barremian, producing light-grey limestones. The CCD shallowed abruptly in the Barremian, and this was accompanied by stagnation of bottom and intermediate water that developed euxinic conditions which extended through the Cenomanian. Bottom circulation was re-established in the Late Cretaceous, but shallow CCD and lack of terrigenous input to the deep basin resulted in deposition of pelagic multicolored clays. Maastrichtian limestone beds within otherwise carbonate-poor variegated clays indicate temporary deepening of the CCD in the North American Basin in the Late Cretaceous. Pelagic and hemipelagic clays were deposited in much of the deep basin during the Paleocene, followed by accumulation of dominantly biogenic siliceous deposits in the deep basin in latest Paleocene through Middle Eocene time. Mixed siliceous and calcareous sediments accumulated on the shallower mid-oceanic ridge. Silica diagenesis formed porcelanitic cherts in the upper Lower to lower Middle Eocene sediments, and these correlate with the widespread seismic reflector Horizon AC. The Upper Eocene and Oligocene are represented by clays with varying amounts of biogenic silica and carbonate, together with locally important mass-flow deposits. Towards the continental margin, sediments of this age are missing because a major pre-Miocene unconformity overlies Lower Cretaceous to Eocene sediments beneath the continental rise. Except for calcareous ridge-flank sediments, deposition of hemipelagic grey-green mud was predominant in the North American Basin throughout the Neogene and continues to the present. The thickest deposits are Miocene and form the continental rise. Mass-flows from the continental shelf and slope deposited a massive blanket of Miocene carbonate breccia (the Great Abaco Member) in the Blake-Bahama Basin, and form flat-lying wedges of dominantly Pleistocene terrigeneous sand, silt, and clay in the present abyssal plains. Abstract Copyright 1979 by the American Geophysical Union.
Year of Publication: 1979
Research Program: DSDP Deep Sea Drilling Project
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Assemblages; Atlantic Ocean; Bermuda Rise Formation; Biostratigraphy; Blake Ridge Formation; Blake-Bahama Formation; Cat Gap Formation; Cenozoic; Cretaceous; Deep Sea Drilling Project; Deposition; Diatoms; Foraminifera; Geophysical methods; Geophysical surveys; Hatteras Formation; Invertebrata; Lithostratigraphy; Lower Cretaceous; Mesozoic; Microfossils; Mineral assemblages; Nannofossils; North American Basin; North Atlantic; Northwest Atlantic; Oceanography; Paleoecology; Plantae; Plantagenet Formation; Protista; Sedimentation; Seismic methods; Stratigraphy; Surveys; Thallophytes; Turbidite
Coordinates: N251109 N372202 W0563203 W0753609
Record ID: 1980017752
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