秦岭-大别-苏鲁造山带白垩纪以来的抬升冷却史——低温年代学数据约束  

Cenozoic denudation and cooling history of Qinling-Dabie-Sulu orogens:apatite fission track thermochronology constraints.

作　　者：胡圣标[1] 郝杰[1] 付明希[1] 吴维平[2] 汪集旸[1] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]安徽省地质调查院,合肥230001

出　　处：《岩石学报》2005年第4期1167-1173,共7页Acta Petrologica Sinica

基　　金：国家重点基础岩浆发展规划项目(973)(G1999075504)资助

摘　　要：总计100个新的磷灰石裂变径迹数据提供了从整体上探讨晚中生代以来抬升冷却史的年代学数据。这些切过东秦岭至黄陵背斜、穿过桐柏至扬子前陆冲断带以及大别和苏鲁超高压变质岩带,南秦岭的裂变径迹年龄与扬子内的黄陵背斜相似,而北秦岭则与桐柏-大别-苏鲁相当。从北秦岭到大别,裂变径迹年龄趋于减小,但过郯庐断裂到苏鲁则略有增加。与我国西部造山带裂变径迹年龄格局相较,桐柏-大别-苏鲁带与西部各造山带显然不是处于同一挤压变形体制下。相对于超高压岩石早期快速的阶段性抬升,即岩浆活动期(～120Ma)后的抬升要和缓得多;相对于其它地质单元,扬子前陆冲断带、黄陵背斜和南秦岭在岩浆活动期后即抬升冷却到了磷灰石裂变径迹封闭温度(～110℃)对应的深度。基于裂变径迹数据和相关Ar/Ar 和 K-Ar 数据进行的冷却史模拟结果显示:全区均表现为相似的三阶段冷却过程:(1)白垩纪早期开始快速抬升至磷灰石裂变径迹退火带的冷却阶段;(2)随后的处于部分退火带的缓慢冷却阶段;(3)上新世以来的加速抬升过程。现今的磷灰石裂变径迹年龄格局基本上受控于白垩纪的快速抬升冷却事件,但最后为晚期活动断裂所定格。A total of 100 new apatite fission track （AFT） data from profiles crossing the eastern Qinling into the Yangtze Craton, the Tongbai into the Yangtze foreland thrust and fault belt,the Dabie and the Sulu UHP metamorphic belts, provide a database to evaluate the late Mesozoic and Cenzoic denudation and cooling history of the Qinling-Tongbai-Dabie-Sulu belt on a regional scale. AFT ages of the south Qinling is similar to the Huangling Anticline ,but older than that of the North Qinling. The North Qinling is comparable with the Tongbai-Dabie-Sulu area. From the north Qingling to the Dabie, the AFT ages tend to decrease toward the Tanlu Fault, but gently increased in Sulu. Comparing with AFT age pattern of the orogenic belts in the western China, the Tongbai Dabie Sulu belt was not under the same continuous compression system of deformation. Relative to the early stage＇s exhumation of the UHP rocks, an overall cooling paths for the UHP metamorphic belt can be outlined ,and it shows that the post-magmatic （ ～120 Ma）cooling was much more modest and evener than the episodic and dramatic cooling in the early stages, and that the Yangtze foreland thrust and fault belt, the Huangling anticline and the south Qinling were cooled to the apatite fission track closure temperature much earlier,just followed the Cretaceous plutons than the others. The modeled thermal histories ,based on the fission track data and incorporated with available Ar/Ar and K-Ar data, exhibit fairly similar three-stage cooling, starting with an Early Cretaceous rapid cooling event, followed by a period of relative thermal stability keeping the rocks at apatite partial annealing zone temperatures, and ending with a new phase of accelerated cooling during the Pliocene to recent. The first cooling phase has been suggested to reflect the large-scale transtensional deformation between ～140 ～110 Ma, which is attributed to the Early Cretaceous eastward tectonic escape and Pacific backarc extension. The present AFT age pattern is, therefore, basi

关 键 词：秦岭-大别-苏鲁 磷灰石裂变径迹 抬升剥蚀 冷却史 

分 类 号：P542.2[天文地球—构造地质学]