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| 龙门山泥盆纪腕足化石锶同位素组成特征及其古环境意义 | |
| 引用本文： | 程红光,李心清,袁洪林,黄思静,王克卓.龙门山泥盆纪腕足化石锶同位素组成特征及其古环境意义[J].地球化学,2009,38(2):187-194. |
| 作者姓名： | 程红光 李心清 袁洪林 黄思静 王克卓 |
| 作者单位： | 1. 中国科学院,地球化学研究所,环境地球化学国家重点实验室,贵州,贵阳,550002;中国科学院研究生院,北京,100049 2. 中国科学院,地球化学研究所,环境地球化学国家重点实验室,贵州,贵阳,550002 3. 西北大学,大陆动力学国家重点实验室,陕西,西安,710069 4. 成都理工大学,油气藏地质及开发工程国家重点实验室,四川成都,610059 5. 新疆地质调查院第一地质调查所,新疆,乌鲁木齐,830011 |
| 基金项目： | 国家自然科学基金，西北大学大陆动力学国家重点实验室开放课题基金 |
| 摘 要： | 生物成因的海相碳酸盐岩中Sr同位素组成与演化是目前研究古海平面变化、造山运动以及古气候变化的主要工具，在海相地层定年及全球等时对比研究中发挥着重要作用。对四川龙门山泥盆纪剖面腕足化石Sr同位素组成进行了研究。保存鉴定结果显示：腕足化石壳体结构保存完整；阴极射线照射下壳体不发光或部分壳体呈微弱橙黄色；大多数壳体微量元素Mn〈250μg／g、Sr〉400μg／g。表明腕足化石保存完好，后期成岩作用影响微弱。锶同位素结果显示：龙门山泥盆纪sr同位素演化同全球泥盆纪Sr同位素演化基本一致，表明龙门山泥盆纪Sr同位素演化受全球性变化影响。早泥盆世较高Sr同位素比值（甘溪组0．708437）可能是受加里东造山运动的影响，大量古陆的出露，风化作用的加强所致。其后的缓慢下降可能受海平面上升古陆面积缩小的影响。中泥盆世Sr同位素组成低值平台显示着幔源Sr和陆源Sr（风化作用较弱）输入量之间的平衡。随后的Sr同位素组成的上升可能是受中泥盆世开始温度上升的影响，致使风化作用的加强所致。 |
| 关 键 词： | Sr同位素 腕足 泥盆纪 龙门山 |
Strontium isotope composition and paleoenvironmental implication of Devonian brachiopod shells from Longmen Mountains |
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| CHENG Hong-guang,LEE Xin-qing,YUAN Hong-lin,HUANG Si-jing,WANG Ke-zhuo.Strontium isotope composition and paleoenvironmental implication of Devonian brachiopod shells from Longmen Mountains[J].Geochimica,2009,38(2):187-194. | |
| Authors: | CHENG Hong-guang LEE Xin-qing YUAN Hong-lin HUANG Si-jing WANG Ke-zhuo |
| Institution: | CHENG Hong-guang1,3,LEE Xin-qing1,YUAN Hong-lin2,HUANG Si-jing4 , WANG Ke-zhuo5 1.State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550002,China,2.State Key Laboratory of Continental Dynamics,Northwest University,Xi'an 710069,3.Graduate University of Chinese Academy of Sciences,Beijing 100049,4.State Key Laboratory of Oil , Gas Reservoir Geology , Exploitation,Chengdu University of Technology,Chengdu 610059,5.No.1 Institu... |
| Abstract: | At present, the composition and evolution of strontium isotopes in biogenic marine carbonate rocks is an important tool for studying sea level change, orogenic movement and paleoelimate, and plays an important role in the global chronostratigraphic correlation and dating. In this study, Devonian brachiopod shells from Longrnen Mountains, Sichuan Province were analyzed for 87Sr/86Sr. The preservation show that the brachiopod shells are well and noncathodoluminscence, and Mn 〈 250μg/g and Sr 〉 400μg/g, indicating that they suffered little diagenetic alteration. The 87Sr/S6Sr ratio reveals the evolution curve of strontium isotope in Devonian from the Longmen Mountains is consistent with the global curve which indicates the 87Sr/86Sr ration from the Longmen Mountains was affected by the global factors. The high 87Sr/S6Sr ratios in Early Devonian were attributed to the increasing of weathering caused by the Caledonian orogeny. And the decline of STSr/86Sr was the result of the reducing of paleoland because of the rise of sea level. In Middle Devonian, low 87Sr/S6Sr ratios and their fluctuation were interpreted to be the result of the balance between riverine strontium flux （weak weathering） and mantle strontium flux. The increase of 87Sr/86Sr ratios in Middle Devonian might caused by the rise of paleotemperature and the enhancing of weathering. |
| Keywords: | strontium isotope brachiopod Devonian Longmen Mountains |
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