A structural and depositional framework for fan deltas in southern Puerto Rico

Conference · Tue May 01 00:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:6675571

Renken, R A ^[1]

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1. Geological Survey, Doraville, GA (USA)

Puerto Rico's southern plain consists of six coalescing fan deltas of Holocene to Miocene age that are bordered to the north by the steep-faced mountains of the Cordillera Central. These fan deltas extend 70 km along the Caribbean Sea and form a narrow plain that ranges from 3 to 8 km in width. A narrow, transitional marine zone separates the subaerial part of the fan from the coast. Possibly due to their poor preservation or subsequent erosion, deeply buried marginal marine fan-delta deposits have not been identified in well core data. Subaerial fan-delta deposits are separated at outcrop and in the subsurface into a fine-grained facies of bedded silt sheet-flow deposits and a coarse-grained facies of boulder to fine sand streamflow deposits. The six fan deltas form an elongate depositional basin nearly parallel to the west-northwest structural trend of the great southern Puerto Rico fault zone. Subsurface mapping indicates that this fault zone, which contains numerous sinistral and high-angle cross faults, probably extends beneath the fan-delta plain. Movement along these faults has resulted in pull-apart basin structures beneath the Salinas fan delta and a releasing bend structure beneath the Ponce-Capitanejo fan deltas. Percentage sand and gravel lithofacies maps show that the trunk streams concentrate coarse-grained material as a narrow proximal channel near the apex or as a midfan lobe. Bedded silt deposits dominate the distal and interfan areas. Thickening-upward sand and gravel beds and thinning-upward silt beds in the distal fan subsurface areas indicate that several fan deltas are part of a coarsening-upward prograding sequence.

• OSTI ID: 6675571
• Report Number(s): CONF-900605-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:5; Conference: Annual convention and exposition of the American Association of Petroleum Geologists, San Francisco, CA (USA), 3-6 Jun 1990; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
58 GEOSCIENCES
PUERTO RICO
ALLUVIAL DEPOSITS
CARIBBEAN SEA
CONGLOMERATES
DRILL CORES
GEOLOGIC FAULTS
LITHOLOGY
OFFSHORE SITES
PETROLEUM DEPOSITS
RESERVOIR ROCK
SEDIMENTATION
STRATIGRAPHY
TERTIARY PERIOD
ATLANTIC OCEAN
CENOZOIC ERA
FEDERAL REGION II
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEOLOGY
GREATER ANTILLES
ISLANDS
MINERAL RESOURCES
NORTH AMERICA
RESOURCES
ROCKS
SEAS
SEDIMENTARY ROCKS
SURFACE WATERS
USA
WEST INDIES
020200* - Petroleum- Reserves
Geology
& Exploration
580000 - Geosciences