Provenance of the Surveyor Fan and Precursor Sediments in the Gulf of Alaska—Implications of a Combined U-Pb, (U-Th)/He, Hf, and Rare Earth Element Study of Detrital Zircons
Provenance of the Surveyor Fan and Precursor Sediments in the Gulf of Alaska—Implications of a Combined U-Pb, (U-Th)/He, Hf, and Rare Earth Element Study of Detrital Zircons
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阿拉斯加湾测量扇和前体沉积物的来源——碎屑锆石 U-Pb、(U-Th)/He、Hf 和稀土元素联合研究的意义
DOI：
10.1086/699740
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Gerdes
中科院分区：
文献类型：
--
作者：
Bahlburg;Berndt;Gerdes
新生代圣伊利亚斯造山带的折返剥蚀历史保存在阿拉斯加湾中新世至全新世测量员范的沉积中。山脉带的造山作用恰逢导致不同程度冰川的主要气候事件，这些冰川被认为与造山过程有强烈的相互作用。为了评估气候和构造对侵蚀模式的相对影响，并重建向海洋的沉积物路线，我们将锆石U-Pb定年和(U-Th)/He热年代学与综合大洋钻探计划探险341个测点U1417和U1418的砂岩和粉砂中的锆石的稀土元素和Hf同位素分析相结合。所有中新世至更新世的沉积物具有相似的U-Pb年龄谱，表明主源区在不同的冰期保持不变。一个50-60 Ma的显著年龄组分可与丘加赫变质杂岩和山脉中的萨纳克-巴拉诺夫深成岩带联系起来。较老的颗粒可归因于丘加赫、威廉王子和雅库塔地体中的低级变质来源。50-60 Ma的火成岩和变质锆石的减少意味着来自Chugach变质杂岩和Sanak-Baranof深成岩带的输入减少。这表明，冰川向南向海洋推进，加上中新世至上新世的构造变化，触发了新冰川区的较高贡献。在更新世冰川作用加剧的时期，冰川似乎与以前一样嵌套在同一区域。我们的数据没有给出更新世期间水系或构造环境发生普遍变化的证据，但也不能证明没有这种变化。
The history of exhumation and denudation of the Cenozoic St. Elias orogen is stored in the sediments of the Miocene to Holocene Surveyor Fan, Gulf of Alaska. The orogeny of the mountain belt coincides with major climatic events leading to varying degrees of glaciation that are considered to have strongly interacted with mountain-building processes. In order to assess the relative influence of climate and tectonics on erosion patterns and to reconstruct sediment routing to the ocean, we combine zircon U-Pb dating and (U-Th)/He thermochronology with analysis of rare earth elements and Hf isotopes of zircons of sands and silts from Integrated Ocean Drilling Program expedition 341 sites U1417 and U1418 in the Surveyor Fan. All Miocene to Pleistocene sediments show similar U-Pb age spectra, indicating that the main source areas remained the same during different stages of glaciation. A prominent age component at 50–60 Ma can be linked to the Chugach Metamorphic Complex and the Sanak-Baranof plutonic belt in the mountain range. Older grains can be referred to low-grade metamorphic sources within the Chugach, Prince William, and Yakutat terranes. A decrease in 50–60 Ma igneous and metamorphic zircons implies a reduction of input from the Chugach Metamorphic Complex and the Sanak-Baranof plutonic belt. This indicates that the southward advance of glaciers toward the ocean, together with tectonic changes from the Miocene to the Pliocene, triggered a higher contribution from the newly glaciated areas. During times of increased glaciation in the Pleistocene, glaciers appear to have been nested in the same area as before. Our data do not give evidence of a general change in the drainage systems or the tectonic setting during the Pleistocene but also do not prove the absence of such.
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影响因子：
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DOI：
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