云南是世界现代植物多样性最为丰富的地区之一，也是生物多样性研究的热点地区。化石植物群是植物在漫长地质时期演化的直接证据，对于探讨现代生物多样性形成过程及其驱动机制具有重要意义。认识生物多样性的形成过程，必然要追溯到地质时期更为久远的化石植物群。在充分开展古植物学研究的基础上，化石植物群可靠的地质年代便成为相关研究的重点和难点。

近年来，中国科学院西双版纳热带植物园古生态研究组在云南南华县吕合镇发现大量保存精美、物种丰富的植物化石，这一植物群以壳斗科和桦木科为优势类群，兼有柳杉属、铁杉属、胡桃科等其他类群，体现了与现代植被极为相似的面貌。版纳植物园古生态组、德国森根堡研究所与其他相关领域的专家合作，在化石层位发现了很难与化石植物群同时存在、可用于测定植物群绝对地质年代的火山岩。通过选取火山岩中的锆石，采用U-Pb法测定的结果显示，这一植物群的绝对年龄为三千三百万年，远远早于之前认为的约一千万年。同时，这一结果使吕合植物群成为目前云南新生代已知最早的大化石植物群，对于认识我国西南地区现代植被与植物多样性起源具有重要意义。

相关研究成果以New U-Pb dates show a Paleogene origin for the modern Asian biodiversity hot spots为题，发表在Geology上。该项目得到了国家基金委中德中心、国家基金委-云南省联合基金、中科院拔尖青年人才计划、青年创新促进会的资助。（来源：中国科学院西双版纳热带植物园）

New U-Pb dates show a Paleogene origin for the modern Asian biodiversity hot spots

Abstract   Yunnan, in southwestern China, straddles two of the world’s most important biodiversity hot spots (i.e., a biogeographic region that is both a reservoir of biodiversity and threatened with destruction) and hosts more than 200 fossiliferous sedimentary basins documenting the evolutionary history of that biodiversity, monsoon development, and regional elevation changes. The fossil biotas appear modern and have been assumed to be mostly Miocene in age. Dating has been by cross-correlation using palynology, magnetostratigraphy, and lithostratigraphy because numerical radiometric ages are lacking. Here we report the first unequivocal early Oligocene age (33–32 Ma) of a section in the Lühe Basin (25.141627°N, 101.373840°E, 1890 m above mean sea level), central Yunnan, based on U-Pb zircon dates of unreworked volcanic ash layers in a predominantly lacustrine succession hosting abundant plant and animal fossils. This section, located in Lühe town, is correlated with an adjacent section in the Lühe coal mine previously assigned to the upper Miocene based on regional lithostratigraphic comparison. Our substantially older age for the Lühe town section calls into question previous estimates for the surface uplift and climate history of the area, and the age of all other correlative basins. The modernization of the biota ~20 m.y. earlier than previously thought overturns existing concepts of vegetation history in southwestern China, and points to Paleogene modernization of the biota in Yunnan and associated Asian biodiversity hot spots.

原文链接：http://www.xtbg.cas.cn/xwzx/kydt/201711/P020171109314934278448.pdf