Calcareous nannofossils and planktonic foraminifera of ODP Hole 132-810C

The 136 m of calcareous oozes recovered in Hole 810C span the interval from upper Maastrichtian to middle Pleistocene. Three major hiatuses interrupt the sequence, with the topmost part of the Maastrichtian through the entire lower Paleocene, most of the lower Eocene, and the entire middle Eocene through most of the middle Miocene missing. Severe reworking and displacement affected the lower part of the succession from the Maastrichtian through the middle Miocene. Reworking and displacement gradually decreased in the upper portion. Calcareous nannofossil biostratigraphy enabled us to calibrate precisely the nearly complete magnetic reversal sequence of the Pliocene to the late Pleistocene. Two minor hiatuses detected by calcareous nannofossils across the Pliocene/Pleistocene boundary and in the upper lower Pleistocene, respectively, resulted in shortening of the Olduvai and Jaramillo Events within the Matuyama Chron of the magnetic reversal sequence.

810C钻孔（Hole 810C）获取的136米钙质软泥（calcareous oozes）沉积序列，覆盖了上马斯特里赫特阶（upper Maastrichtian）至中更新世（middle Pleistocene）的地质时段。该序列存在三处主要沉积间断（hiatuses）：马斯特里赫特阶最顶部至完整的古新统（Paleocene）下部、绝大多数始新统（Eocene）下部，以及完整的始新统中部至中新统（Miocene）中部大部分地层均发生缺失。马斯特里赫特阶至中新统中部的下部地层序列，遭受了强烈的再改造（reworking）与地层位移（displacement）作用；上部地层的再改造及位移程度则逐渐减弱。通过钙质超微化石生物地层学（calcareous nannofossil biostratigraphy）研究，我们得以精准校准上新世（Pliocene）至晚更新世（late Pleistocene）近乎完整的磁反转序列（magnetic reversal sequence）；分别在更新世/上新世界线（Pliocene/Pleistocene boundary）及早更新世上部地层中，通过钙质超微化石识别出两处小型沉积间断，该间断导致磁反转序列松山极性时（Matuyama Chron）内的奥杜威事件（Olduvai Event）与哈拉米洛事件（Jaramillo Event）的记录被缩短。