古新统─始新统界线与事件沉积

PALEOCENE-EOCENE BOUNDARY AND EVENT SEDIMENTATION

深海钻探揭示的古新统—始新统界线上许多全球性变化引起了地质学家的普遍关注。这些变化包括：岩性上从海绿石石英砂岩变化到粘土岩、粘土矿物组合从伊利石／蒙脱石为主变化为高岭石为主、大陆植物群的绝灭和迁移、钙质超微化石物种更新速度加快、底栖有孔虫绝灭和分异度降低、碳氧同位素强烈负异常、大陆哺乳动物演化发生变化、大气环流强度减弱、海洋环流模式改变、海平面上升、海底热液活动呈１～２个数量级加强。通过对古新世—始新世的地层沉积学、古生物学、古气候学和古海洋学研究，确认古新统—始新统地层界线是全球构造事件的结果，表现为全球板块边界重组、扩张中心和转换断层模式改变、海底热液活动呈１～２个数量级加强。

Lots of global changes at the Paleocene-Eocene (P-E) boundary discovered by Deep Sea Drilling Peoject have attracted geologists's attention. They include a change in lithology from glauconitic quartz sand to clay; a change in clay mineral suites fromillite/smectite-dominated to kaolinite-dominated; the extinction and migration in the terrestrial flora; an increased species turnover rate in marine calcareous nanofossils; the extinction and lower diversity in the benthic foraminiferal assemblages; a considerable extension in δ18O and δ13C values; a change in the evolution of land mammals; a significant reduction of the intensity of atmospheric circulation; a change in the style of abyssal circulation;an increase in water depth; and 1￣2 order of magnitude increase in hydrothermal activity at the P-E boundary. It is concluded that the P-E boundary was the result of global tectonic events. By researching in lithology, palaeobiology, palaeoclimatology,palaeoceanography of the P-E stratigraphic sections, it is convinced that the events include that global plate boundary rearrangement, changes in patterns of spreading centers and transform faults, and increase in hydrothermal activity.