全新世以来大青山山前冲洪积扇的期次划分及其影响因素

The period division and influencing factors of the alluvial fans in front of the Daqing Mountains since Holocene

文中在区域地质调查基础上,利用光释光和碳十四年代学结果对大青山山前冲洪积扇进行了期次划分。结果表明,全新世以来大青山山前发育三期冲洪积扇,其时代依次为:Ⅰ期冲洪积扇(11.4-8ka BP)、Ⅱ期冲洪积扇(8-5.5ka BP)、Ⅲ期冲洪积扇(2.8ka BP-至今),分别对应了全新世早期、中期和晚期。在此基础上,将各期冲洪积扇与同时期的构造活动和古气候对比分析,各期冲洪积扇的形成发育是构造活动和古气候共同叠加作用的结果,其中区域构造作用对冲洪积扇形成演化的影响更大。从早全新世至今,三期冲洪积扇的规模依次减小,这与全新世以来区域构造活动减弱有关。对大青山山前冲洪积扇进行期次划分并建立年代学框架,有利于更加全面地理解大青山山前地区地形地貌的演化过程,为后续相关研究提供理论基础。

Based on the results of the field geological survey and the chronology of OSL and AMS14C, the alluvial fans of Daqing Mountain were studied, and then the stages of the alluvial fans were divided. The Holocene Daqing Piedmont developed three stages of alluvial fans, the ages of which are respectively: stage I(11.4-8 ka BP), stage II(8-5.5 ka BP) and stage III(2.8 ka BP-now), corresponding to the early, middle and late Holocene respectively. The comparative analysis of paleoclimate change and tectonic activity between the development age of alluvial fans and the corresponding period was conducted. The results show that the formation and development of fan bodies in each period was the result of the interplay of tectonic and paleoclimate, and the regional tectonic activity had a greater impact on the formation and evolution of alluvial fans. From the early Holocene to now, the scale of the three stages of alluvial fans has decreased in turn, which was related to the gradual weakening of regional tectonic activity since the Holocene. In order to understand the geomorphic evolution process of Daqing Piedmont area more comprehensively and provide theoretical basis for the follow-up research, the chronology framework of the alluvial fans in Daqing Piedmont is established.