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Enigmatic Mid-Proterozoic Orogens: Hot, Thin, and Low
Geophysical Research Letters ( IF 4.6 ) Pub Date : 2021-07-30 , DOI: 10.1029/2021gl093312
Christopher J. Spencer 1 , Ross N. Mitchell 2 , Michael Brown 3
Affiliation  

Since the Archean, secular change in orogenic style is demonstrated through evolution of metamorphic conditions and geochemical proxies. Linked to orogenic style is the amount of crustal thickening and elevation, whereas orogenic vigor is related to the supercontinent cycle. An array of Proterozoic orogens spanned the assembly of supercontinents Columbia and Rodinia, but the vigor of orogenesis is debated, with proposals for both Mesoproterozoic quiescence and climax. We show mid-Proterozoic orogenesis occurred globally and was broadly continuous; furthermore, orogens exhibit elevated metamorphic thermobaric ratios with large volumes of high-temperature felsic magmatic rocks. These features reflect higher mantle heat flux leading to increased mid-crustal flow and lower elevation. In this context, proposals that geochemical proxies for crustal thickness record orogenic quiescence are inconsistent with the geological record. Alternatively, secular change in crustal thickness is attributed to orogenic style, namely the prevalence of hot, thin, and low orogens in the mid-Proterozoic.

中文翻译:

神秘的中元古代造山带:热、薄、低

自太古宙以来,造山风格的长期变化通过变质条件和地球化学代理的演变得到证明。与造山风格相关的是地壳增厚和抬高的数量,而造山活力与超大陆旋回有关。一系列元古代造山带跨越了哥伦比亚和罗迪尼亚超大陆的集合,但造山作用的活力是有争议的,并提出了中元古代静止和高潮的建议。我们显示中元古代造山作用发生在全球范围内并且是广泛连续的;此外,造山带具有大量高温长英质岩浆岩的变质温压比升高。这些特征反映了较高的地幔热通量,导致中地壳流动增加和海拔降低。在这种情况下,建议地壳厚度记录造山静止的地球化学代理与地质记录不一致。或者,地壳厚度的长期变化归因于造山风格,即中元古代中热、薄和低造山带的盛行。
更新日期:2021-08-19
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