Episodic uplift of the Tianshan Mountains since the late Oligocene constrained by magnetostratigraphy of the Jingou River section, in the southern margin of the Junggar Basin, China
Episodic uplift of the Tianshan Mountains since the late Oligocene constrained by magnetostratigraphy of the Jingou River section, in the southern margin of the Junggar Basin, China
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DOI：
10.1029/2007jb005064
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发表时间：
2008-05
影响因子：
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通讯作者：
Junliang Ji;P. Luo;Paul White;Hanchao Jiang;Ling Gao;Z. Ding
中科院分区：
文献类型：
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作者：
Junliang Ji;P. Luo;Paul White;Hanchao Jiang;Ling Gao;Z. Ding
[1]准噶尔盆地南缘新生代巨厚沉积是天山隆升变形的产物。为了更好地确定天山的构造历史，我们对位于天山北方皮埃蒙特的金沟河剖面进行了详细的磁性地层学研究。在安集海河组出露基底至西峪组中部3000多米厚的剖面上，共采集了1133个样品，建立了磁性地层学。根据两个脊椎动物化石点和与CK 95地磁极性时标的良好对比，推测该剖面的沉积时代为1030.5 ~ 104.6Ma，根据沉积速率外推，西峪组顶部的年龄为102.6Ma。研究结果表明，天山造山带在1026 - 22.5Ma、1013 -11 Ma和107 Ma时，沉积速率显著增加，沉积环境发生了显著变化，代表了天山造山带的初始隆升。以及随后的两次快速隆升事件。此外，沉积速率的变化意味着天山的隆升。是幕式的，时间相对较短，有强烈的变形与长期的构造软弱或平静的时间间隔。
[1] Thick Cenozoic sediments in the southern margin of the Junggar Basin accumulated in response to the uplift and deformation of the Tianshan Mountains. To better constrain this mountains' tectonic history, we report a detailed magnetostratigraphic study of the Jingou River section, located in the northern piedmont of the Tianshan Mts. A total of 1133 samples were used to establish the magnetostratigraphy of a more than 3000 m thick section from the exposed base of the Anjihaihe Formation to the middle of the Xiyu Formation. Two vertebrate fossil sites and a good correlation with the CK95 geomagnetic polarity timescale suggest that the section was deposited from ∼30.5 to ∼4.6 Ma and the age of the top of the Xiyu formation is ∼2.6 Ma based on an extrapolation of the sedimentation rates. Our results show that significant increases in sedimentation rates as well as notable changes in depositional environments occurred at ∼26–22.5 Ma, ∼13–11 Ma and ∼7 Ma, which represent the initial uplift of the Tianshan Mts. and two subsequent rapid uplift events. In addition, changes in sedimentation rates imply that the uplift of the Tianshan Mts. was episodic, and relatively short, with intervals of intensified deformation with long periods of tectonic weakness or quiescence.