摘要
柴达木盆地中、新生界富含微体化石 ,节肢动物介形类分布尤其广泛 ,其中Cetacella、Cypridea、Austrocypris、Hemicyprinotus、Cyprideis和Ilyocyprisinermis是晚侏罗世以来各相关层位的标准化石。这些水生生物的绝灭或发生均很迅速 ,在区域或全球范围内均可对比 ,具有生物事件地层学意义 :Cetacella属的绝灭可能是侏罗、白垩纪之交全球性的古气候降温和气候带变化在柴达木盆地的反映 ;早白垩世之后Cypridea的迅速衰退是地外因素灾变的结果 ;中始新世晚期的Austrocypris的绝灭、渐新世Hemicyprinotus的绝灭都与当时地质条件的改变存在着内在的联系 ;中中新世Cyprideis的爆发推断是青藏高原隆升 ,导致气候干燥、湖水咸化的结果 ;而晚更新世晚期I .inermis等介形类动物群的急剧衰减则与全球气候骤然变冷的末次冰期事件有关。
The Mesozoic-Cenozoic in the Qaidam Basin contain abundant microfossils, especially in Ostracoda among which Cetacella、Cypridea、Austrocypris、Hemicyprinotus、Cyprideis and Ilyocypris inermis are index fossils for specific stratigraphical sequences since the Late Jurassic. The extinction or appearance of these Ostracoda always occurred in a short time interval, and can be correlated locally and globally, so they are of importance in bioeventstratigraphy. This article listed six such biological events in Qaidam Basin and discussed their causes. The extinction of Cetacella reflected temperature decrease at global scale and changes of palaeoclimate zones during the latest Jurassic and the earliest Cretaceous; The rapid decline of Cypridea in the earliest Cretaceous may be a result of the strikes of small planets; at the latest middle Eocene Austrocypris became extinct, and at Oligocene Hemicyprinotus disappeared. These events related to the changes of the geological conditions at that time. The explosion of Cyprideis at the middle Miocene was because the rise of Qinghai-Xizang Plateau which resulted in the dry climate and development of salt lakes. The rapid decrease of Ostracoda in the Late Pleistocene resulted from the last glacial stage in which the global climate became extremely cold.
出处
《古地理学报》
CAS
CSCD
2000年第3期69-74,共6页
Journal of Palaeogeography:Chinese Edition
关键词
柴达木盆地
中生代
新生代
介形类
绝灭
Qaidam Basin, Ostracoda, extinction, explosion, bioeventstratigraphy