南黄海中部隆起晚白垩世以来地层剥蚀的磷灰石裂变径迹分析

南黄海中部隆起自印支期以来经历显著的构造隆升及剥蚀过程.基于大陆架科学钻探CSDP-2井的钻井岩心，应用磷灰石裂变径迹技术研究了南黄海中部隆起晚白垩世以来的剥蚀过程及响应特征.所获得的8个磷灰石样品的裂变径迹年龄显示出两个年龄组，除单个样品为38±3 Ma外，其余样品都集中在（52±4）~（65±5）Ma范围内，基本反映了同一期构造热事件年龄，并且均远小于样品所处的二叠纪年龄，表明样品完全退火并记录了晚白垩世以来的热历史.样品热史模拟结果表明，基于泥岩镜质体反射率计算的最高古地温处于样品退火带温区范围内，各样品从晚白垩世早期（约100 Ma）以来经历持续的降温过程，在约80~75 Ma开始进入部分退火带.南黄海中部隆起第一期快速冷却降温过程出现在晚白垩世末期，并持续至古新世早期，随后进入古近纪表现为持续相对缓慢的降温过程，降温幅度约30 ℃，渐新世末期到中新世早期存在另一期快速冷却过程.热史模拟结果较好地指示了南黄海中部隆起晚白垩世以来的地层剥蚀响应特征. 

Apatite Fission Track Constrains on Denudation since Late Cretaceous in Central Uplift,South Yellow Sea Basin

Significant tectonic uplift and denudation occurred in central uplift of the South Yellow Sea basin (SYSB) since Late Cretaceous. Based on the drilling cores of CSDP-2 well which is supported and carried out by the Continental Scientific Drilling Project (CSDP) of China Geological Survey (CGS), the denudation and related characteristics of thermal history since Late Cretaceous in central uplift of SYSB were analyzed by apatite fission track (AFT) technique. The eight AFT ages obtained show two age groups, with one at (38±3) Ma, and the others ranging from (52±4) Ma to (65±5) Ma which all are much younger than the age of Permian where all samples locate, indicating that the samples were completely annealed and recorded the thermal history since Late Cretaceous. Modeling results of thermal history show that the peak paleo-geotemperature calculated by testing data of vitrinite reflectance (Ro) is within the range of the temperature interval of annealing zone of AFT. All samples suffered continuous cooling processes from the early stage of Late Cretaceous (ca.100 Ma) and started to enter into partial annealing zone (PAZ) at about 80-75 Ma. The first rapid cooling process began at the end of Late Cretaceous, and continued to the Early Paleocene, then was followed by a stage of slow cooling process during Paleogene. Some samples show the other rapid cooling process which is weaker than the first that occurred from the Late Oligocene to Early Miocene. The AFT ages and modeling results of thermal history significantly show the denudation and related characteristics since Late Cretaceous in central uplift of SYSB.