北大巴山凤凰山基底隆起晚中生代构造隆升历史--磷灰石裂变径迹测年约束  

Apatite fission track thermochronologic constraint on Late Mesozoic uplifting of the Fenghuangshan basement uplift

作　　者：李建华[1,2] 张岳桥[1,2] 董树文[3] 施炜[1,2] 李海龙[1,2] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]国土资源部新构造运动与地质灾害霞点实验室,北京100081 [3]中国地质科学院,北京100037

出　　处：《地质科学》2010年第4期969-986,共18页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国土资源部“深部探测技术与实验研究”专项(编号:SinoProbe-08-01)资助

摘　　要：对采自于北大巴山凤凰山基底隆起8个样品的磷灰石裂变径迹年代学分析和热历史模拟表明,凤凰山基底隆起陆内造山运动结束后的隆升历史大致可以划分为2个阶段:早白垩世中晚期(135±5～95±5 Ma)缓慢隆升,晚白垩世(95±5～65±5 Ma)快速隆升。大巴山北缘韧性剪切带黑云母^(40)Ar-^(39)Ar坪年龄证实大巴山北缘中晚侏罗世(165.7±1.9 Ma～161.2 Ma)存在快速隆升剥蚀,其与大巴山强烈陆内造山作用阶段有关;早白垩世中晚期缓慢隆升代表了陆内造山结束后的稳定阶段;晚白垩世快速隆升为一次区域性隆升事件,在秦岭、大别和武当等地区均有反映,隆升过程中伴随着强烈的伸展垮塌作用,沿秦岭造山带发育一系列伸展断陷盆地。区域对比分析表明,凤凰山基底隆起隆升历史与黄陵、汉南地块接近,但与武当地块存在明显区别,反映了秦岭造山带的不均一隆升过程。南大巴山前陆带1个样品的热史模拟结果显示,南大巴山前陆带自早白垩世以来与凤凰山基底隆起经历了一致的隆升过程。8 rock samples were collected from the Fenghuangshan basement uplift zone of the northern Dabashan tectonic belt. Apatite fission track （AFT） dating were carried out and their time-temperature thermal modelings were performed. The results show the uplifting history can be divided into two stages since Early Cretaceous： late Early Cretaceous slow uplifting（ 135±5 95±5 Ma） , Late Cretaceous rapid uplifting （95 ±5 - 65 ±5 Ma）. The biotite 40Ar/39Ar plateau age from mylonite in the Dabashan ductile shearing zone documents there was a rapid uplifting in the age of 165.7±1.9 Ma - 161.2 Ma,it was related to intensive intracontinental orogenesis of the Mrs. Dabashan. The late Early Cretaceous slow uplifting represented a period of relative stability after Late Jurassic intracontinental orogenesis. The Late Cretaceous rapid uplifting was concomitant with post-orogenic extension and collapse of the Dabashan tectonic belt, featured by the development of rifted basins along the Qinling orogenic belt. This Late Mesozoic uplifting history of Fenghuangshan basement uplift can be compared with those of the adjacent basement uplift zones such as the Huangling and Hannan terrains, but differs significantly from the Wudang terrain of southern Qinling, indicating an unhomogeneous uplifting process of the Qinling orogenic belt in Late Mesozoic period. One rock sample was collected from the foreland structural zone, its time-temperature thermal modeling result shows a similar uplifting history between the Fenghuangshan basement uplift zone and the foreland structural zone since Early Cretaceous.

关 键 词：磷灰石裂变径迹(AFT) 晚中生代 构造隆升 大巴山 风凰山基底隆起 

分 类 号：P542[天文地球—构造地质学] P597[天文地球—地质学]