AN INTEGRATED LATEST QUATERNARY (STAGE-3 TO PRESENT) PALEOCLIMATIC AND PALEOCEANOGRAPHIC RECORD FROM OFFSHORE NORTHERN NEW-ZEALAND

Paleoceanographic and onshore paleoclimatic changes during the last 59 ,000 yr are established from three deep-sea sediment cores off northea st New Zealand using an integrated log of sediment texture, CaCO3 cont ent, palynology, and planktonic and benthic foraminiferal delta(18)O a nd delta(13)C data, together with dated silicic tephras. These records from the isotopic stage 4-3 boundary to the present record northern N ew Zealand vegetation history, changes in a subsidiary equatorward flo w of Circumpolar Deep Water, and sea-surface temperatures (SSTs) for s ubtropical water (STW) between latitudes 36 degrees 42' and 35 degrees 51'S. Relative to the Holocene, isotopically derived SSTs record aver age changes of +2 degrees C, -2 degrees C, and -2 degrees C for the 59 ,000-43,000, 43,000-24,000, and 24,000-12,000 yr time slices, respecti vely, The apparent +2 degrees C warming for the 59,000-43,000 yr perio d is interpreted to reflect changes in the dominant depth habitat of G lobigerina bulloides in response to upwelling. A -2 degrees C cooling of SSTs during isotope stage 2 is interpreted, in part, to reflect upw elling of cool subsurface water resulting from strong and persistent w esterly airflow across New Zealand, with the concomitant enhanced surf ace-water production of CaCO3. Onshore, vegetation consistent with the se changes are recorded, with full conifer-hardwood forest prior to 43 ,000 yr, followed by a change to vegetation implying cooler and drier conditions between 43,000 and 12,000 yr, and a subsequent return to fu ll forest during the Holocene. The sequence of biopelagic and hemipela gic sedimentation observed within these cores reflect oscillation of s ea level about a threshold eustatic level that controls the transport of terrigenous detritus offshore. Local variations and interplay of th e regional oceanography and morphology and tectonism of the continenta l shelf will dictate that, relative to present sea level, this thresho ld eustatic sea level will vary in depth, and hence age, along a conti nental margin, Data from the New Zealand region reveal an extremely st eep meridional thermal gradient across the southern and central New Ze aland region during the last glaciation with minor cooling of STW to t he north, apart from localized nearshore upwelling zones, but pronounc ed cooling of subantarctic water to the south of the subtropical conve rgence zone. (C) 1995 University of Washington.