郯庐断裂带对鲁西隆升过程的影响:磷灰石裂变径迹证据

Impaction of the Tan-Lu Fault Zone on uplift of the Luxi Rise: Constraints from apatite fission track thermochronology

郯庐断裂带(TLFZ)是一条贯穿华北的NNE向巨型断裂带。新生代以来,在郯庐断裂带的两侧及其内部发生了显著的伸展构造变形,形成了泰安-莱芜-蒙阴NW向断陷盆地群,并使鲁西块体发生了急剧的陆内伸展隆升。本文在前人研究的基础上,分别在鲁西沂山、徂徕山和蒙山三处进行了大量的样品采集,总计完成了25个样品的测试,获得了一系列新的磷灰石裂变径迹(AFT)年代学结果。结合前人已发表的裂变径迹结果,对鲁西地区新生代与伸展变形有关的剥露-隆升作用的时空分布特征、隆升剥露模式及隆升幅度进行分析,并揭示郯庐断裂带在鲁西新生代热隆升过程中的影响。主要认识有:1)新生代以来,鲁西主要经历了始新世-早渐新世和新近纪以来两期快速剥露-隆升阶段。2)始新世-早渐新世主要表现为幕式差异性快速剥露-隆升,鲁西南受NW向断层控制形成向北、向东的掀斜抬升作用,鲁西北受NE向断裂控制,形成向北、向西的掀斜抬升作用。新近纪以来,进入相对低速区域性剥露-隆升阶段。3)AFT模拟显示,与始新世-早渐新世的幕式快速剥露-隆升相比,中新世以来,鲁西剥露-隆升速率相对减小,但剥蚀量剥露-抬升量较大。故鲁西整体抬升于中新世以来。4)结合前人研究成果,新生代以来,鲁西宏观上受郯庐断裂带伸展活动影响,越靠近郯庐断裂带剥蚀量越大,局部受NW或NE向断裂控制。

Tan-Lu Fault Zone（ TLFZ） is a large-scale NNE-trending fault zone cross the eastern part of the North China Block. The intracontinental extension on both sides and the internal of TLFZ are prominent in the Cenozoic,which produced Tai ＇an-LaiwuMengyin basins and result in fast uplift of the Luxi Rise. On the basis of the previous studies,25 Apatite Fission Track（ AFT） samples were collected from the Yi Mt. profile,Culai Mt. profile and Meng Mt. profile,respectively. Combined our new AFT data with some published AFT data,this paper determines the onset time,spatial distribution and pattern of the Cenozoic uplift and exhumation,and discusses the impaction of TLFZ on the Cenozoic uplift and exhumation. The main conclusions are as follows： 1） The Luxi Rise underwent mainly two-stage rapid extension-related uplifts in Eocene-Early Oligocene and since Miocene. 2） Episodic uplifting in the Eocene-Early Oligocene is controlled by NW-trending fault in the southwestern Luxi with eastward and northward tilting-related uplift and exhumation,and is controlled by NE-trending fault in the northeastern Luxi with westward and northward tilting-related uplift and exhumation. 3） The AFT model shows episodic uplifting with a faster erosion rate,following small denudation during Paleogene and a steady uplifting with a slower erosion rate but larger denudation since the Miocene. The results also show that the uplift of the main Luxi Rise developed since the Miocene. 4） Our and pervious results reveal that the Cenozoic uplift and exhumation in the Luxi Rise is controlled by the TLFZ on the whole,displaying more rapid closer to TLFZ and locally being affected by NW- and/or NE-trending faults.