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首页> 外文期刊>Precambrian Research >Neoarchean suprasubduction zone ophiolite discovered from the Miyun Complex: Implications for Archean-Paleoproterozoic Wilson cycle in the North China Craton
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Neoarchean suprasubduction zone ophiolite discovered from the Miyun Complex: Implications for Archean-Paleoproterozoic Wilson cycle in the North China Craton

机译：NeoArchean suprasubduction区Ophiolite从Miyun Complex发现：在华北Craton中对Archean-PaleoproteroZoice威尔逊循环的影响

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摘要

The North China Craton (NCC) offers a window to Archean-Paleoproterozoic crustal evolution. Following the amalgamation of microblocks during Neoarchean, the NCC witnessed another protracted Wilson cycle in the Paleoproterozoic with subduction-accretion-collision process. Here we report a newly identified suprasubduction zone ophiolite suite from the Miyun complex in the NCC where a rare and near-complete ophiolite succession is preserved including serpentinite, lherzolite, olivine clinopyroxenite, websterite, gabbro, dolerite, diorite, monzonite, metabasalts and trondhjemite, in association with Banded Iron Formation (BIF). The geochemical features of the suite are consistent with those of suprasubduction ophiolite complexes, with the mafic and intermediate members displaying Island Arc Tholeiite (IAT) and Mid-Ocean Ridge Basalt (MORB) affinity. Zircon grains from lherzolite define three groups of Pb-207/Pb-206 weighted mean ages at 2500 +/- 12 Ma marking the formation age, and 2237 +/- 47 Ma, and 1843 +/- 30 Ma representing subsequent thermal events. The majority of zircon grains in olivine clinopyroxenite, gabbro, and quartz monzonite yield 207Pb/206Pb weighted mean ages of 2510 +/- 19 Ma, 2495 +/- 10 Ma, and 2486 +/- 21 Ma respectively. Those from the trondhjemite show weighted mean age of 2476 +/- 9.4 Ma. The compiled age data from all the rock types in the Miyun suite show two distinct age peaks at ca. 2486 Ma and 1832 Ma, corresponding to the timing of magma differentiation and subsequent metamorphism. The zircon Lu-Hf isotope data display distinct positive epsilon Hf(t) values in the range 0.35-7.05, suggesting magma derived from Neoarchean to Paleoproterozoic depleted mantle (juvenile) source. The zircon TDM ages show a peak at 2670 Ma, confirming Neoarchean components. The timing of magma formation in the Miyun ophiolite is broadly identical to those of the other rare Neoarchean - early Paleoproterozoic ophiolite suites described from the NCC including those from Yishui and Zunhua. Furthermore, evidence from the recently reported Alaskan-type intrusions and arc root mafic-ultramafic complexes around Miyun complex with ages in the range of 2.4-2.0 Ga suggest continued subduction-related magmatic processes, with final collision in latest Paleoproterozoic at around 1.84 Ga. We propose that following the assembly of ancient microblocks along multiple zones of ocean closure marked by major greenstone belts of 2.6-2.5 Ga, and high-grade metamorphism along the margins of the microblocks during Archean-Paleoproterozoic transition, the NCC went through another major Wilson cycle from early to late Paleoproterozoic involving prolonged subduction, accretion and collision of larger crustal blocks and intervening arc complexes, leading to final cratonization.
机译：North中国Craton（NCC）为Archean-PaleProteroZoic地壳演进提供了一个窗口。在NeoArchean期间微嵌段融合后，NCC在古邦古代中目睹了古普朗佐的另一个悬垂的威尔逊循环，具有俯冲 - 吸收碰撞过程。在这里，我们报告了NCC中的Miyun综合体的新鉴定的Suasubducke区Ophiolite套件，罕见和接近完全的眼科继承，包括蛇形素，Lherzolite，Olivine Clossoceite，韦斯特，Gabbro，Dolerite，Diority，Monzonite，Metabasalts和Trondhjemite与带状铁形成（BIF）相关联。该套件的地球化学特征与Suprasub uppaulation络合物的地球化学特征一致，其中乳头和中间成员显示岛Arc Tholeiite（IAT）和中海脊玄武岩（Morb）亲和力。来自LherzoLite的锆石谷物定义了三组PB-207 / PB-206加权平均年龄，标志着形成年龄，2237 +/- 47 mA，1843 +/- 30 mA，代表后续的热敏发生。橄榄石临床中的大多数锆石颗粒，Gabbro和石英单硝石产量207pb / 206pb加权平均值为2510 +/- 19 ma，2495 +/- 10 mA和2486 +/- 21 mA。来自Trondhjemite的那些展示加权平均年龄为2476 +/- 9.4 mA。 Miyun套件中所有岩石类型的编译年龄数据显示了CA的两个不同年龄峰。 2486 mA和1832 mA，对应于岩浆分化和随后的变质的时序。锆石Lu-HF同位素数据显示在0.35-7.05范围内的不同正εHF（t）值，暗示从新台学源于古普罗古奇耗尽的地幔（少年）来源的岩浆。锆石TDM年龄在2670 mA时显示出峰值，确认新轴心组件。 Miyun Ophiolite中岩浆形成的时序与来自NCC中描述的其他罕见的新古古典杂交套件（包括来自Yishui和Zunhua）的其他罕见的新古古典古古木套房。此外，来自最近报道的阿拉斯加型入侵和弧根MAFIC-ultramafic-Ultramafic复合物周围的Miyun综合体，在2.4-2.0 GA的范围内，持续的俯冲相关的魔法过程，最新古地区的最终碰撞左右1.84克。我们建议在沿着多个海洋封闭区域的古代微块组装，由大型绿岩皮带为2.6-2.5 Ga的主要绿岩皮带，沿着微块的边缘在Archean-ogleoprotozoico转型期间沿着微块的边缘，NCC通过另一个主要的威尔逊从早期到后期古地区的循环涉及延长的俯冲，较大的地壳块的凝结和碰撞，并介入弧形复合物，导致最终的裂缝。

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