作者：丁素因，童永生，William C.，CLYDE, Paul L. KOCH, 孟津，王元青，Gabriel J. BOWEN, 李茜，Kathryn E. SNELL

摘要：对广东南雄盆地、江西池江盆地、安徽潜山盆地、湖南衡阳盆地和内蒙古二连盆地古新世和早始新世沉积物进行的生物地层学、化学地层学和磁性地层学研究，第一次给亚洲早古近纪地层框架提供了严格的年代限定。亚洲古新世和早始新世地层划分为4个生物年代单位(陆生哺乳动物期)，从老到新为上湖期、浓山期、格沙头期和伯姆巴期4个亚洲陆生哺乳动物期。南雄盆地古地磁数据显示上湖期的底界约位于C29r的上2/3位置。南雄盆地的古地磁资料及池江盆地最新的古地磁和同位素结果显示上湖−浓山期界线在C27n的上部和C26r的下部之间，接近C27n-C26r转换界面。这一记录支持将上湖−浓山期的界线与北美陆生哺乳动物期中的Torrejonian-Tiffanian期以及海相记录中丹尼−塞兰特期(Danian-Selandian)的界线相对比。二连盆地古地磁和同位素研究表明典型的格沙头动物群延续至C24r, 并且可能向下延伸至C25r和C26n。南雄盆地的记录指示浓山组和古城村组可能相当于C26r的上部。这些结果表明亚洲哺乳动物分期中的浓山−格沙头期的界线可能在北美哺乳动物分期的Tiffanian期中。衡阳盆地的古地磁和同位素证据指示，以短暂的碳同位素漂移为标志的古新世−始新世界线出现在栗木坪组和岭茶组之间，位于C24r中，与海相记录中的坦尼特−伊普里斯期(Thanetian-Ypresian)界线一致。伯姆巴期岭茶动物群的时代似乎与北美Wasatchian-0带的动物群可以比较。上湖期和浓山期动物群主要由亚洲特有的动物组成。发生在上湖期和浓山期界线处的动物群更替，与北美Torrejonian-Tiffanian期界线以及丹尼−塞兰特期界线一致。在相隔很远的生态系统上的这种巧合，可能反映出各自独立的对气候变化的生态和/或进化上的响应。格沙头动物群的地方性色彩更弱，有与北美Clarkforkian期动物群共有的属一级分类单元。伯姆巴动物群是全球性的。现生哺乳动物各目在格沙头−伯姆巴期界线处突然出现，与北美和欧洲的记录一致，显示动物群的更替与古新世−始新世界线处短暂出现的全球变暖事件(又称古新世−始新世高温事件)有关。

关键词：亚洲，古新世，早始新世，年代学

卷期：49卷 01期

ASIAN EARLY PALEOGENE CHRONOLOGY AND MAMMALIAN FAUNAL TURNOVER EVENTS

Ting Su-yin, Tong Yong-Sheng, William C. Clyde, Paul L. Koch, Meng Jin, WANG Yuan-Qing, Gabriel J. Bowen, Li Qian, Kathryn E. Snell

Abstract  Biostratigraphic, chemostratigraphic, and magnetostratigraphic studies of the Paleocene and early Eocene sediments in the Nanxiong Basin of Guangdong, Chijiang Basin of Jiangxi, Qianshan Basin of Anhui, Hengyang Basin of Hunan, and Erlian Basin of Nei Mongol, China, provide the first well-resolved geochronological constraints on stratigraphic framework for the early Paleogene of Asia.
Asian Paleocene and early Eocene strata are subdivided into four biochronological units (Land Mammal Ages). From oldest to youngest, they are the Shanghuan, the Nongshanian, the Gashatan, and the Bumbanian Asian Land Mammal Ages (ALMA). Paleomagnetic data from the Nanxiong Basin indicate that the base of the Shanghuan lies about 2/3 the way up Chron C29r. Nanxiong data and recent paleomagnetic and isotopic results from the Chijiang Basin show that the Shanghuan-Nongshanian ALMA boundary lies between the upper part of Chron C27n and the lower part of Chron C26r, close to the Chron C27n-C26r reversal. This record favors a correlation of Shanghuan-Nongshanian ALMA boundary to the Torrejonian-Tiffanian North American Land Mammal Age (NALMA) boundary and to the Danian-Selandian stage boundary in the marine record. The paleomagnetic and isotopic data from the Erlian Basin show that typical Gashatan faunas persist into Chron C24r and may range into Chron C25r and possibly C26n, and the records from the Nanxiong Basin indicate that both Nongshan and Guchengcun formations may correlate to the upper part of Chron C26r. These results would imply that the Nongshanian-Gashatan ALMA boundary may correlate within the Tiffanian NALMA. The paleomagnetic and isotopic evidence from the Hengyang Basin indicates that the transient carbon isotope excursion that marks the Paleocene-Eocene boundary is present between the Limuping and Lingcha formations, and the boundary is placed at the uppermost reversed polarity interval correlated to Chron C24r and to the Thanetian-Ypresian stage boundary in the marine record. The Bumbanian Lingcha fauna seems to correlate with the Wasatchian-0 faunal zone of North America to within ~10⁴ yr.
Both Shanghuan and Nongshanian faunas are mainly composed of Asian endemic taxa. The coincidence of faunal turnover at the Shanghuan-Nongshanian boundary with the Torrejonian-Tiffanian boundary and Danian-Selandian stage boundary in far separated ecosystems may indicate independent ecologic and/or evolutionary response to climatic changes. The Gashatan fauna shows less endemism and has taxa shared with those of the Clarkforkian NALMA in North America at the generic level. The Bumbanian fauna is cosmopolitan. A sudden appearance of modern mammalian orders at the Gashatan-Bumbanian boundary is the same pattern as observed in North America and Europe, indicating the faunal turnover is related to the transient global warming event at the Paleocene-Eocene boundary known as the Paleocene-Eocene Thermal Maximum (PETM).
Key words  Asia, Paleocene, early Eocene, chronology