Major climatic changes in surface waters of the Japan Sea since the early middle Miocene

Conference · Tue Jan 09 04:00:00 EST 1990 · EOS, Transactions, American Geophysical Union; (United States)

OSTI ID:6883999

Brunner, C A ^[1]; Rahman, A ^[2]; Koizumi, I ^[3]; White, L D ^[4]; Alexandrovich, J M

---

1. Center for Marine Sciences, MS (United States)
2. Univ. of Utah, Salt Lake (United States)
3. Osaka Univ. (Japan)
4. Univ. of California, Santa Cruz (United States)

The Japan Sea cooled from a subtropical to a temperature and subpolar biogeographic province during the early middle Miocene based on assemblages of planktonic foraminifers and calcareous nannofossils. High productivity persisted from 8 to 2 Ma as in other marginal basins of the Pacific rim based on the presence of diatom ooze, diatom clays, and diatom silty clays. Sea ice formed in the northern Japan Sea in short episode 4.5 and 4.0 Ma prior to the onset of extensive Northern Hemisphere glaciation 2.5 Ma. Sea ice reappeared between 2.7 and 2.4 Ma, 2.3 Ma, and between 0.9 and 0.7 Ma based on occurences of sea ice diatoms. Conditions in late Quaternary watermasses fluctuated in response to glacial cycles based on variable in assemblage composition, preservation, and abundance of radiolarians, planktonic foraminifers, and calcareous nannofossils. The relationship between surficial watermass conditions and cyclic deposition of dark brown, carbon-rich sediments constrains several hypotheses on depositional environment of the unusual lithology.

• OSTI ID: 6883999
• Report Number(s): CONF-9002174--
• Conference Information: Journal Name: EOS, Transactions, American Geophysical Union; (United States) Journal Volume: 71:2
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540110*
540210 -- Environment
Terrestrial-- Basic Studies-- (1990-)
ALGAE
AQUATIC ECOSYSTEMS
ASIA
CENOZOIC ERA
CHROMOPHYCOTA
CLIMATIC CHANGE
DEVELOPED COUNTRIES
DIATOMS
EARTH PLANET
ECOSYSTEMS
ENVIRONMENTAL EFFECTS
GEOLOGIC AGES
GEOLOGY
GLACIERS
JAPAN
LITHOLOGY
MIOCENE EPOCH
NORTHERN HEMISPHERE
PETROLOGY
PLANETS
PLANTS
QUATERNARY PERIOD
SEAS
SEDIMENTS
SURFACE WATERS
TERTIARY PERIOD