Detailed sedimentological investigations were performed on sediments from DSDP-Site 594 (Chatham Rise, east of NZ) in order to reconstruct the evolution of paleoclimate and paleooceanographic conditions in the Southwest Pacific during the last 6 million years. The results can be summarised as follows: 1. High accumulation rates of biogenic opal and carbonate and the dominance of smectites in the clay fraction suggest increased oceanic productivity and an equable dominantly humid climate during the late Miocene. 2. During Pliocene times, decreasing contents of smectites and increasing feldspar/quartz ratios point to an aridification in the source area of the terrigenous sediments, culminating near 2.5 Ma. At that time, accumulation rates of terrigenous components distinctly increased probably caused by increased sediment supply due to intensified atmospheric and oceanic circulation, lowered sea level, and decreased vegetation cover. 3. A hiatus (1.45 to 0.73 Ma) suggests intensified intermediate-water circulation. 4. Major glacial/interglacial cycles characterize the upper 0.73 Ma. During glacial times, oceanic productivity and terrigenous sediment supply was distinctly increased because of intensified atmospheric and oceanic circulation and lowered sea level, whereas during interglacials productivity and terrigenous sediment supply were reduced. 5. An increased content of amphiboles in the sediment of Site 594 indicates increased volcanic activities during the last 4.25 Ma.

West: 140.0000 East: 180.0000 North: -20.0000 South: -40.0000

Expedition: 90

Site: 90-594

Provider: SEDIS Publication Catalogue

Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=1999-027851 (c.f. for more detailed metadata)

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