New beach ridge type: severely limited fetch, very shallow water

Conference · Thu Sep 01 04:00:00 EDT 1988 · AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States)

OSTI ID:6374991

Tanner, W F; Demirpolat, S

The southern end of Laguna Madre (Texas) north of the Rio Grande mouth is marked by very shallow water, wide tidal flats, lunettes, islands made of beach ridges, and lesser features. The number and variety of islands in the lagoon is remarkable. The lunettes (clay dunes) are made primarily of quartz sand and coarse silt. They are common 5-10 m high, irregular in shape, and steep sided. They were deposited from wind transport and did not migrate. Those that are islands in the lagoon predate present position of sea level. Islands made of beach ridges were built from the lagoon side. Photoanalysis, field work, and granulometry all show that this sand was not moved into these ridges by Gulf of Mexico waves. Trenches in 12 beach ridges showed horizontal bedding but neither low-angle nor steep cross-bedding (quite unlike swash-built beach ridges). The ridges were built by wind-tide lag effects, not from the swash. Therefore, these beach ridges are a new type, in addition to swash-built, eolian, and storm-surge ridges. Growth of the ridges appears to be completed.

• Research Organization: Florida State Univ., Tallahassee (USA)
• OSTI ID: 6374991
• Report Number(s): CONF-8810362-
• Conference Information: Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Journal Volume: 72:9
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
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& Exploration
ALLUVIAL DEPOSITS
DEPOSITION
FEDERAL REGION VI
GEOLOGIC DEPOSITS
ISLANDS
NORTH AMERICA
TEXAS
USA