Miocene-Early Pliocene diatomaceous sedimentation patterns in the Pacific: A response to paleooceanography and paleoclimatic change

Conference · Tue May 01 04:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:6747570

Barron, J A ^[1]

---

1. Geological Survey, Menlo Park, CA (USA)

Biosiliceous sediments greatly expanded their distribution in the North Pacific during the late early to early middle Miocene (18-15 Ma), at least partly due to enhanced basin-basin fractionation of deep waters between the North Atlantic and North Pacific, which began in 17 Ma. Subsequently, in the late middle and late Miocene, diatomaceous sedimentation responded to the following series of successive cooling steps. (1) High-latitude cooling between 14.9 and 12.4 Ma caused an intensification of upwelling in the marginal North Pacific as evidenced by a wider distribution of laminated sediments and a decline in carbonate preservation. (2) Cooling across the middle Miocene-late Miocene boundary (10.3-9.2 Ma and 9.0-8.3 Ma) led to further increases in upwelling and raised biogenic opal accumulation rates in upwelling regions of the eastern equatorial Pacific, California, and Peru. (3) Cooling in the latest Miocene to earliest Pliocene (6.2-4.8 114a) resulted in further regional differentiation of biosiliceous sedimentation patterns in the North Pacific, probably reflecting steeper productivity gradients in upwelling regions. Biogenic opal accumulation rates declined in the eastern equatorial Pacific, but probably increased in coastal upwelling regions off California, Peru, and in the Bering Sea. (4) A decline in diatom sedimentation in waters off southern California during the earliest Pliocene (4.5-4.0) Ma coincided with a period of warmer paleotemperatures and a decline in opal accumulation rates in the equatorial Pacific. A major increase in biosiliceous sedimentation in the Southern ocean occurred at this same time.

• OSTI ID: 6747570
• Report Number(s): CONF-900605--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Journal Volume: 74:5
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
CENOZOIC ERA
GEOLOGIC AGES
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
PACIFIC OCEAN
SEAS
SEDIMENTARY BASINS
SEDIMENTATION
SURFACE WATERS
TECTONICS
TERTIARY PERIOD