中国西南部地区晚三叠世卡尼期气候事件：成因、过程及研究意义

The Late Triassic "Carnian Event", characterized by a signi?cant episode of more humid climatic conditions, is a hallmark Event in the evolution of the Triassic climate and deposits. In SW China, this event is indicated with the lithological change from carbonate rocks to black shale or slates (or igneous rocks) at the boundary between the lower and upper Carnian. After this Carnian event, siliciclastic beds gradually increased in the upper Carnian. Two major sections situated at Hanwang, Mianzhu County of NW Sichuan, Genlonggou, Changtai County of West Sichuan will be detected and sampled in detail. The rocks collected from the Carnian paleoclimatic event deposits in these major sections plus several minor sections, will be measured with the techniques of stable isotope, trace elements, X-ray diffraction, etc. The isotopic ages of the igneous rocks covering on the Lower Carnian carbonate rocks will be measured using the Ar-Ar or U-Pb techniques. Being aimed at the Carnian Event deposits in SW China, stratigraphical, paleontological, sedimentological and geochemistrical study, e.g. the biostratigraphic correlation between the Carnian Event deposits in SW China and in the West Tethys, will be carried in the planning research. Furthermore, the causes, processes and the implications for paleoclimate of the Carnian geological event will be discussed. The complex evolutionary relationships among the paleoclimatic, paleoceanic changes, the tectonic movements and the carbon cycles of the ecosystem are planned to reveal according to the geochemical data and the petrological, sedimentological, paleontological analyses.

选择川西北地区绵竹汉旺、川西-藏东地区昌台根隆沟剖面为主要剖面，辅以其它卡尼阶露头剖面，以反映卡尼期气候事件和卡尼期碳酸盐生产危机的上、下卡尼阶界线地层为主要研究对象；通过地层剖面详细测制与采样，进行沉积构造观察、古生物分析与鉴定，测试川西-藏东地区卡尼期火成岩精确的同位素年龄和主要研究剖面连续地层岩样的微量元素、全岩及有机质碳稳定同位素并进行综合分析，以地层学、古生物学、沉积学和地球化学方法综合研究我国西南部地区卡尼期气候事件沉积，探讨这一幕式气候变化在东特提斯地区的影响，并与西特提斯地区卡尼阶进行对比；以系统论的观点研究这一地质事件发生的原因和过程，深刻认识晚三叠世卡尼期地球系统中古气候、碳循环、古海洋变化及构造运动之间的复杂演化关系。

选择川西北地区绵竹汉旺、安县雎水、江油马鞍塘剖面等为主要剖面，以卡尼阶为主要研究对象，通过露头剖面详细测制与采样，进行沉积学、地层学、古生物学、地球化学、古地磁学综合研究，探讨了这一幕式湿润气候变化在川西北地区的影响，并与西特提斯地区卡尼阶进行了对比。观察了大量显微薄片，测试了卡尼阶沉积岩有机碳同位素、碳酸盐岩碳氧同位素、微量元素和锆石同位素年龄，采集了古植物、菊石、腕足及双壳化石并进行了鉴定，进行了孢粉、牙形石分离与鉴定，在川西北地区卡尼阶地层学研究方面取得进展，发现了发育于中卡尼期以及拉丁期末期的古喀斯特界面，孢粉测试结果显示古特提斯东部沿海地区在卡尼期出现构造变化，对川西地区卡尼期古环境及构造演化有了进一步认识。研究结果认为川西北地区卡尼阶显示了由鲕粒灰岩（或微晶灰岩）到海绵丘灰岩（或生屑灰岩）到陆源碎屑岩的岩性变化。在汉旺观音崖、青岩沟以及安县雎水剖面，卡尼阶硅质海绵丘灰岩发育，鉴定出的牙形石Quadralella polygnathiformis显示鲕粒灰岩为卡尼期沉积，在雎水剖面海绵丘灰岩之上的灰黑色泥质粉砂岩中产出的丰富的菊石为Discotropitid和Juvavitid组合，显示为Tuvalian亚阶下部层位。海绵丘共发育2个期次，第一期海绵丘之上发育的黑色页岩可能可与细特提斯地区卡尼期湿润气候事件有关联，海绵丘的死亡可能是淡水输入以及构造运动引发的海平面升降联合作用的结果。该课题资助发表学术论文12篇，其中SCI论文3篇。