Late Cenozoic exhumation and erosion of the Taiwan orogenic belt: New insights from petrographic analysis of foreland basin sediments and thermochronological dating on the metamorphic orogenic wedge
Late Cenozoic exhumation and erosion of the Taiwan orogenic belt: New insights from petrographic analysis of foreland basin sediments and thermochronological dating on the metamorphic orogenic wedge
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DOI：
10.1016/j.tecto.2018.09.003
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发表时间：
2019-01-05
期刊：
影响因子：
2.9
通讯作者：
Syu, Shih-Jie
中科院分区：
文献类型：
--
作者：
Chen, Wen-Shan;Yeh, Jia-Jhih;Syu, Shih-Jie
台湾造山楔两侧前前陆盆地和后前陆盆地中记录的晚新生代造山带沉积物对沉积物源演化具有重要的制约作用，并进一步勾勒出造山带的折返剥蚀历史。我们提供了前前陆盆地和后前陆盆地7个代表性地区的172个砂岩岩石学数据，并结合雪山山脉前楔体和主干山脉后楔体的以往热年代学数据，阐明了源区造山楔体与其伴生的前陆盆地之间的源汇关系。我们的数据分析和估算提供了证据，证明前前陆盆地和后前陆盆地造山带的初始沉积年龄与邻近造山带的折返和剥蚀历史相一致，表明主干和雪山山脉分别在12 Ma和5-6 Ma左右开始堆积。造山沉积和造山隆升的历时开始也表明了前陆盆地逐渐向南和向西迁移的趋势，以及造山楔由于斜向碰撞而随着时间的推移而不对称地折返和侵蚀。台湾造山作用开始的时间约为12 Ma，形成了主干山脉的后向楔形，比以往确定的台湾造山运动开始年龄约为6 Ma要早得多。我们将台湾造山演化分为两个阶段：第一阶段是中中新世碰撞前，由主干山脉的鱼犁带形成的俯冲楔体的挤压和折返。第二阶段为弧陆碰撞阶段，产生双重强烈的造山楔体挤压作用，形成了雪山和中新世晚期以来主干山脉的历时隆起史。
Late Cenozoic orogen-derived sediments recorded in the pro- and retro-foreland basins on both sides of the Taiwan orogenic wedge provide important constraints on sediment provenance evolution, and further outline the exhumation and erosion histories of the orogenic belt. We present 172 sandstone petrographic data from seven representative regions on the pro- and retro-foreland basins, which we coupled with previous thermochronological data from the pro-wedge of the Hsuehshan Range and the retro-wedge of the Backbone Range to elucidate the source-sink relationships between a source orogenic wedge and its associated foreland basin. Our data analysis and estimation provide evidence that the initial depositional age of orogen-derived sediments in pro- and retro-foreland basins is consistent with the exhumation and erosion histories of the adjacent orogen, indicating that the Backbone and Hsuehshan Ranges started to build up at similar to 12 and 5-6 Ma, respectively. The diachronous onset of orogenic sediment deposition and orogenic uplift also suggest a tendency for progressively southward and westward migration of the foreland basin, and asymmetric exhumation and erosion of the orogenic wedge over time due to oblique collision. The timing of the onset of the Taiwan orogeny formed the retro-wedge of the Backbone Range at similar to 12 Ma, which is much older than the previously determined onset age of Taiwan mountain building of similar to 6 Ma. We divide the Taiwan orogenic evolution into two stages: the first stage comprises the extrusion and exhumation of the subduction wedge formed as the Yuli Belt of the Backbone Range prior to the collision during the middle Miocene. The second stage comprises the arc-continent collision, producing doubly vergent orogenic wedge extrusion, leading to a diachronous uplift history of the Hsuehshan and Backbone Ranges since late Miocene.