Andrews, P. B. and Ovenshine, A. T. (1975): Terrigenous silt and clay facies; deposits of the early phase of ocean basin evolution

Leg/Site/Hole:
DSDP 29
Identifier:
1976-016984
georefid

10.2973/dsdp.proc.29.131.1975
doi

Creator:
Andrews, P. B.
U. S. Geol. Surv., Menlo Park, Calif., United States
author

Ovenshine, A. T.
author

Identification:
Terrigenous silt and clay facies; deposits of the early phase of ocean basin evolution
1975
Initial Reports of the Deep Sea Drilling Project
Texas A & M University, Ocean Drilling Program, College Station, TX, United States
29
Lyttleton, N. Z. to Wellington, N. Z.; March-April 1973
1049-1063
A terrigenous silt and clay facies has been shown to be the first sediment to accumulate on basement (both oceanic and continental) at many sites drilled during Leg 29, and at many DSDP sites in the Indian Ocean and Tasman Sea drilled during earlier legs. It is divided into two subfacies: a burrow-mottled subfacies which predominates and a bedded subfacies which is rare. The burrow mottled subfacies is dark olive-gray to dark brown, burrow mottled, organic-rich, pyrite, glauconite, and micronodul-bearing. It is a poorly sorted, clayey silt to clay, composed of land-derived detritus, and is characterized by a very restricted flora and fauna, the latter being dominated by siliceous, and agglutinating benthonic foraminifera. The upper third of the subfacies is silicified wherever the overlying sediments are rich in siliceous microfossils. It is inferred that the subfacies accumulated where bottom waters were oxygenated, but circulation was sluggish. It is further inferred that the subfacies accumulated during the early sea-floor-spreading phase in the evolution of the respective ocean basins. The bedded subfacies forms units that alternate with the burrow mottled subfacies at one site. It consists of slightly graded beds clayey silt. The microfossils are shallow-water benthonic foraminifera and neritic nannofossils. Graded beds are interpreted as turbidites.
English
Coverage:Geographic coordinates:
North:-30.0000
West:143.0000East: 177.0000
South:-57.0000

Oceanography; accumulation; biogenic structures; bioturbation; Cenozoic; clastic sediments; clastics; clay; Cretaceous; Deep Sea Drilling Project; environmental analysis; evolution; genesis; Leg 29; lithofacies; lithostratigraphy; marine geology; Mesozoic; mineral composition; ocean basins; Pacific Ocean; provenance; sea-floor spreading; sedimentary structures; sedimentation; sediments; sequence; silt; sorting; South Pacific; southwest; Southwest Pacific; stratigraphy; Tasman Sea; terrigenous; Tertiary; West Pacific;

.