The changing course of the Orinoco River during the neogene

Conference · Mon Feb 01 04:00:00 EST 1993 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:6064825

Diaz de Gamero, M L ^[1]

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1. Universidad Central de Venezuela, Caracas (Venezuela)

Recent studies have revealed that the varied fresh-water vertebrate fossil fauna of the Urumaco Formation in northwestern Falcon, of Late Miocene age, belongs biogeographically to the Orinoco River system. This makes possible to chart the changing course of the Orinoco River through the Neogene. The Misoa delta of Lake Maracaibo, of middle Eocene age, was probably constructed by a proto-Orinoco river that ran in a south-north direction, draining the Central Cordillera of Colombia and the Guayana Highlands. The late Eocene uplifting of western Venezuela changed the paleogeographic setting, with no evidence of delta-building during the Oligocene. In the earliest Miocene, the Falcon Basin was the site of marine shale sedimentation. In the second half of the Early Miocene, a deltaic sequence was initiated in northwestern Falcon that continued, except for a transgressive episode, until the end of the Middle Miocene, depositing a total thickness of over 2.5 km. The Urumaco overlies this sequence and its vertebrate fauna indicates that the river that built the previous delta was the proto-Orinoco. The initial uplifting of the northern part of the Andes and the western edge of the Caribbean Mountains can thus be dated to occur at the end of the Middle Miocene, causing the distal course of the river to move to a west-east direction. The sedimentary record of the Orinoco River delta appears in the Maturin Basin of eastern Venezuela at the end of the Miocene, and is especially evident in Trinidad and the Columbus Basin during the Pliocene and Pleistocene.

• OSTI ID: 6064825
• Report Number(s): CONF-930306--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 77:2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
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58 GEOSCIENCES
580000 -- Geosciences
ANDES
CARBONACEOUS MATERIALS
CENOZOIC ERA
COASTAL REGIONS
COLOMBIA
DEPOSITION
DEVELOPING COUNTRIES
DIMENSIONS
EOCENE EPOCH
FRESH WATER
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LESSER ANTILLES
MAPPING
MATERIALS
MIOCENE EPOCH
MOUNTAINS
ORIGIN
OROGENESIS
OXYGEN COMPOUNDS
PALEONTOLOGY
RIVER DELTAS
RIVERS
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SEDIMENTATION
SHALES
SOUTH AMERICA
STREAMS
SURFACE WATERS
TERTIARY PERIOD
THICKNESS
TRINIDAD AND TOBAGO
VENEZUELA
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WEST INDIES