Detachment faulting in a bivergent core complex constrained by fault gouge dating and low-temperature thermochronology
Detachment faulting in a bivergent core complex constrained by fault gouge dating and low-temperature thermochronology
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DOI：
10.1016/j.jsg.2019.103865
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发表时间：
2019-10-01
影响因子：
3.1
通讯作者：
Hampel, Andrea
中科院分区：
文献类型：
--
作者：
Heineke, Caroline;Hetzel, Ralf;Hampel, Andrea
土耳其西部孟得勒斯地块中部是一个以两条逆剪切作用滑脱断裂为特征的双辐合变质核杂岩。本文利用断层泥的K-Ar年龄和氢同位素数据，以及基岩样品中磷灰石和锆石的裂变径迹和(U-Th)/He年龄来约束滑脱断裂的时间。K-Ar年龄与低温热年代学年龄的对比表明，Gediz拆离西端在240 ~ 70℃之间存在脆性断裂，K-Ar年龄在12 ~ 5 Ma之间，表明中新世中期以来存在较为连续的断裂；该滑脱的东部主要为上新世期的快速滑动期。相比之下，Buyuk Menderes拆离群的K-Ar年龄在22-16和9-3 Ma，为两期断裂提供了证据，这与新的和已发表的低温热年代学资料一致。氢同位素比值为-76 ~ -115‰，表明滑脱断裂和断层泥形成过程中有大气水入渗。上盘和下盘岩石最年轻的K-Ar年龄和冷却历史表明，这两个分离体的活动结束于3 Ma以前，即目前活跃的地堑建立的时候。
The central Menderes Massif in western Turkey is a bivergent metamorphic core complex characterised by two detachment faults that operated with opposite sense of shear. Here, we present K-Ar ages and hydrogen isotope data for fault gouge as well as fission track and (U-Th)/He ages for apatite and zircon from bedrock samples to constrain the timing of detachment faulting. Comparison of the K-Ar ages and low-temperature thermochronologic ages indicates brittle faulting at temperatures between similar to 240 and similar to 70 degrees C. At the western termination of the Gediz detachment, K-Ar ages between similar to 12 and similar to 5 Ma suggest rather continuous faulting since the mid-Miocene; a Pliocene phase of rapid slip is mainly recorded in the eastern part of this detachment. In contrast, K-Ar ages from the Buyuk Menderes detachment cluster at 22-16 and 9-3 Ma and provide evidence for two phases of faulting, which is in accordance with new and published low-temperature thermochronologic data. Hydrogen isotope ratios of -76 to -115 parts per thousand indicate infiltration of meteoric water during detachment faulting and gouge formation. The youngest K-Ar ages and cooling histories for hanging and footwall rocks imply that the activity of both detachments ended similar to 3 Ma ago when the currently active grabens were established.