Neogene Exhumation of the Tordrillo Mountains, Alaska, and Correlations With Denali (Mount Mckinley)
Neogene Exhumation of the Tordrillo Mountains, Alaska, and Correlations With Denali (Mount Mckinley)
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阿拉斯加托德里罗山脉的新近纪发掘及其与麦金利山（麦金利山）的相关性
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发表时间：
2013
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通讯作者：
J. Spotila
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作者：
P. Haeussler;P. O’Sullivan;Aaron Berger;J. Spotila
为了更好地了解阿拉斯加山脉西部托尔德里洛山脉的造山时间，从古新世花岗岩中收集了10个样品的磷灰石裂变径迹（AFT）和磷灰石（U-Th）/He（AHe）热年代学，海拔295和3231米之间。在一个样品上测得锆石裂变径迹年龄为59 Ma，与结晶年龄60 Ma相近。一个AFT样品显示出在35 Ma时快速冷却的证据，其他样品在2023 Ma时有一个快速冷却的初始阶段，然后是一段相对稳定的时期，直到206 Ma开始的另一个快速冷却阶段。来自最高的两个样品的AHe数据也表明在6-8 Ma快速冷却。其余样品的AHe年龄大于AFT年龄，在一种情况下，年龄大于一致的U/Pb锆石年龄，这可能是由于磷灰石晶体的环带。Tordrillos AFT数据与先前发表的德纳里地区AFT数据的比较表明，两者都经历了从106 Ma开始的快速冷却。由于大量的斯特林组上新世沉积物填充了邻近的苏西特纳和库克湾盆地，因此，折返的时间也代表了地表隆起。我们推断，阿拉斯加山脉的中部和西部的同步隆起发生的结果，阿拉斯加南部，南部的德纳里断层逆时针旋转，作为雅库塔特微板块碰撞和平板俯冲的远场效应。
To better understand the timing of mountain building of the western Alaska Range in the Tordrillo Mountains, a preliminary suite of 10 samples from Paleocene granite was collected for apatite fission track (AFT) and apatite (U-Th)/He (AHe) thermochronology from elevations between 295 and 3231 m. We obtained a zircon fission track age on one sample of 59 Ma, which is close to the 60 Ma age of crystallization. One AFT sample shows evidence of rapid cooling at 35 Ma, and the others had an initial phase of rapid cooling at ∼23 Ma, followed by a period of relative stability until another phase of rapid cooling that started at ∼6 Ma. AHe data from the highest two samples also indicate rapid cooling at 6-8 Ma. The remainder of the samples have AHe ages older than the AFT ages and in one case older than the concordant U/Pb zircon date, which may be due to zonation of the apatite crystals. Comparison of the Tordrillos AFT data with previously published AFT data from the Denali area indicates both experienced rapid cooling starting at ∼6 Ma. The timing of exhumation also represents surface uplift because voluminous Pliocene sediments of the Sterling Formation fill the adjacent Susitna and Cook Inlet basins. We infer that synchronous uplift of the central and western Alaska Range occurred as a result of counterclockwise rotation of southern Alaska, south of the Denali fault, as a far-field effect of the Yakutat microplate collision and flat-slab subduction.