Sea Surface Temperature And Migrations Of The Subtropicalfront Of Canterbury Basin, New Zealand During MIS6~12

In this research the study area is Canterbury Basin, which located in the middle of the South Island of New Zealand’s Canterbury Plains. The denudation detritus by the uplift of Southern Alps provided material source for the sedimentary. The ocean front and ocean currents such as Subtropical Water and Subantarctic Water also strongly influenced the deposition of the basin. Therefore, the study area is the ideal area to explore the relationship between the migration of STF and deposition process and paleooceanographical environment changes.This study selects the 9H-18H(75-163.8m) of IODP317-U1352 B core to research. Reconstruct the changes of SST since MIS6-12(150-450ka) by the Mg/Ca of planktonic foraminifera Globigerina bulloides. Then explore the changes of marine environment since the late Quaternary of the research area by combining the analysis of the granularity characteristic and the organic carbon content. We found that:In 150-450 ka, sea-level changes in the research area was mainly influenced by regional process of sedimentation, and consistented with global sea-level changes; the migration of the STF was controlled by both sea-level changes and climate changes; the paleoproductivity was mainly affected by the terrigenous nutrient, and also influenced by the SST changes to a certain extent. In MIS7, MIS11 and early MIS9, due to the warm climate, STF migrated to seaward, SST was higher, Southern Alps glaciers melted, terrigenous input increased, which leaded to the adequate supply of nutrients, high deposition rate, coarse granularity and high productivity; In MIS6 and MIS8, these indicators changes on the contrary; In late MIS9, due to the rising sea-level, STF migrated to landward, granularity characteristic was mainly affected by the low SST, which leaded to low deposition rate, fine granularity and low surface productivity; In MIS10, STF migrated frequently, which made the stronger change of water property, high deposition rate and high productivity was likely to be affected by the higher SST.