Sediment evolution within shallow reef-front environments of Mariana Island arc
Sediments collected in shallow reef-front waters (6-20 m) off seven islands in the Mariana Island arc have been analyzed for composition and texture. Samples were collected at 54 stations where the modifying influence of stream runoff was negligible. These deposits are highly varied binary mixtures; coarser, poorly sorted reef-derived bioclastics and finer, better-sorted terrigenous materials. Bioclastic sediment diversity and individual taxa variability are greatest both within the finer size fractions overall and in samples collected around the southern limestone-capped islands of the older arc. Reef/terrigenous detritus variation at the sampled depths is generally controlled by extrabasinal parameters including island area; percent exposed volcanic terrain; wind-exposure direction; and perhaps volcanic activity and/or latitude. Bioeroder population differences among the islands could also be a significant factor in compositional variability. For siliciclastics, size and sorting are strongly influenced by the wave-energy distribution and depth, whereas for bioclastic particles, polymodal grain-size distributions imply that skeletal geometry and availability as well as depth and bioeroder activity are controlling the modification of textures. As indicated by factor analysis, bioclastic sediment variability can be simplified into two sources: framework carbonate clasts in coarser sediments, and non-framework particles in finer sizes. The bioclastic fraction appears to evolve from coarse low-diversity shallow-water assemblages, dominated by reef framework particles, to fine sands in deeper water, composed of a more diverse mixture of smaller non-framework skeletal materials.
- OSTI ID:
- 6083016
- Report Number(s):
- CONF-880301-
- Resource Relation:
- Conference: Annual meeting of the American Association of Petroleum Geologists, Houston, TX, USA, 20 Mar 1988
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
03 NATURAL GAS
MARIANA ISLANDS
PETROLEUM GEOLOGY
NATURAL GAS DEPOSITS
SEDIMENTATION
PETROLEUM DEPOSITS
SEDIMENTS
GEOLOGIC HISTORY
BIOGEOCHEMISTRY
EXPLORATION
REEFS
SILICATES
CHEMISTRY
GEOCHEMISTRY
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
GEOLOGY
ISLANDS
MINERAL RESOURCES
NORTH AMERICA
OXYGEN COMPOUNDS
RESOURCES
SILICON COMPOUNDS
TRUST TERRITORY OF THE PACIFIC ISLANDS
USA
020200* - Petroleum- Reserves
Geology
& Exploration
030200 - Natural Gas- Reserves
Geology
& Exploration