IMPACT EVENTS AND ITS EFFECTS ON PALAEOENVIRONMENT: EVIDENCE FROM ODP SITE 1144 CORE A
撞击事件对古环境的影响——来自ODP1144站A孔样品的证据

The study on microtektites of Ocean Drilling Project(ODP) site 1144 core A around Brunhes/Matuyama boundary indicated the impact event had happened in mid Pleistocene. In this paper we use shell of foraminifera G.sacculifer to determine their C and O isotope compositions. The results indicate that C and O isotope components had changed( δ13 C reduced and δ18 O ascend) in the late stage of microtektite event. The main reason of changes of C and O isotope components is because a part of target rock can be melted and boil away by huge energy when exterrestrial object shocked the Earth so the oxygen( δ18 O) and carbon( δ13 C) isotope composition of atmosphere can be transferred and in the mean time a large of clastic debris and shocking dust can be displaced into stratosphere and diffused to the seven seas. These clastic debris and shocking dust can reduce radialization of the sun and result in the temperature and photosynthesis reduced, so biologic acts weakened and amount of CO2 decreased. In relative to carbon( δ13 C) isotope composition,the oxygen( δ18 O) isotope composition is ascend.