The Atlantic and its bordering continents; a wrench tectonic analysis; lithospheric deformation, basin histories and major hydrocarbon provinces

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Author(s): Storetvedt, Karsten M.; Longhinos, Biju
Author Affiliation(s): Primary:
University of Bergen, Institute of Geophysics, Bergen, Norway
University College Trivandrum City, India
Volume Title: New Concepts in Global Tectonics
Source: New Concepts in Global Tectonics, Vol.64, p.30-68. Publisher: New Concepts in Global Tectonics, Higgins, A.C.T., Australia. ISSN: 1833-2560
Note: In English. 210 refs.; illus., incl. geol. sketch maps
Summary: Main facets of the Alpine tectonic revolution for the 'continental hemisphere' are evaluated in the context of Global Wrench Tectonics. Particular attention is paid to the pan-global system of rectilinear fractures--presumably implanted in the late Archaean and intensified throughout Proterozoic and post-Precambrian times. The progressive dynamically-enforced mechanical break-up of the lithosphere, along with the development of deep and thin-crusted oceanic basins during the Mesozoic, the late Cretaceous lithosphere was tectonically more deformable than ever before. Hence, the mechanical prerequisite of the Alpine revolution was in place. Increased crustal loss to the mantle during Upper Mesozoic had led to a certain planetary acceleration--in turn giving rise to inertia-driven torsion of the outer brittle layer. In this process, the continental masses stayed with their deep mantle roots. For the Atlantic bordering continents, the azimuthal changes were moderate--resulting only in a minor reshaping of the evolving between-continent oceanic basins, from an original configuration of parallel opposing margins to their present southward fanning-out shapes. The Alpine re-shaping of the Atlantic basins led to considerable shear reactivation of the predesigned rectilinear fracture system, involving along-fault mineralogical changes--the basis of linear marine magnetic anomalies. In this wrenching process, the present curvilinear shape of many oceanic fracture zones was established. As the larger continental masses were internally deformed, concurrently with the reshaping of adjacent oceanic basins, tectonic discontinuities along the evolving continental margins were either minimal (Pacific) or non-existent (Atlantic). Hence, many on-land tectonic structures will have their natural continuation into the deep sea basins. For example, the Pelusium tectonic system of Central Africa extends across the Equatorial Atlantic and northern South America, before continuing into the adjacent equatorial Pacific. The increasing deformation of the lithosphere in Meso-Caenozoic times apparently led to accelerated alteration of the Earth's crust. Fluid-enforced sub-crustal eclogitization and associated delamination of the original continental surface layer led to basin formation on various scales; this process opened up pathways for mantle fluids and gasses leading to a range of geological, biological and environmental consequences. Using wrench tectonics as an operational and predictive guide, we suggest that all major oil and natural gas provinces in the world are associated with avenues for upward transport of mantle volatiles. It follows that water, high concentration brines, crude oil and natural gas, and occasionally magma, moves towards the surface as planetary degassing products. There are now good reasons for considering that all major petroleum provinces are fed from the deep Earth--probably making many of them capable to produce forever.
Year of Publication: 2012
Research Program: DSDP Deep Sea Drilling Project
Key Words: 16 Structural Geology; 29 Economic Geology, Energy Sources; Africa; Archean; Arctic region; Atlantic Ocean; Basin analysis; Brazil Basin; Canada; Cretaceous; DSDP Site 355; Deep Sea Drilling Project; Digital data; Discontinuities; Eastern Canada; Europe; Faults; Greenland; Leg 39; Lithosphere; Mesozoic; Newfoundland; Newfoundland and Labrador; North Atlantic; Paleogeography; Paleomagnetism; Plate tectonics; Precambrian; Sea-level changes; South America; South Atlantic; Structural controls; Svalbard; Transgression; Upper Cretaceous; Wrench faults
Coordinates: S154236 S154235 W0303601 W0303602
Record ID: 2014088228
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.