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首页> 外文期刊>Precambrian Research >SHRIMP U-Pb zircon age constraints on the tectonics of the Neoarchean to early Paleoproterozoic transition within the Mulgathing Complex, Gawler Craton, South Australia
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SHRIMP U-Pb zircon age constraints on the tectonics of the Neoarchean to early Paleoproterozoic transition within the Mulgathing Complex, Gawler Craton, South Australia

机译：SHRIMP U-Pb锆石年龄限制在南澳大利亚Gawler Craton的Mulgathing构造体中的新古构造到早古元古代构造的构造中

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摘要

The Mulgathing Complex within the Gawler Craton, South Australia, preserves evidence for magmatism, sedimentation and metamorphism spanning the transition between the Neoarchean and Paleoproterozoic (ca. 2555-2410 Ma). Prior to this study, limited data were available to constrain the timing of these tectonothermal events. We report SHRIMP zircon U-Pb dating of metamorphosed sedimentary and magmatic rocks from the Mulgathing Complex that shows metasedimentary gneisses (Christie Gneiss) have maximum depositional ages ca. 2480 Ma, in contrast to previous studies that have suggested deposition had occurred ca. 2510 Ma. The oldest metamorphic zircons in our data are ca. 2465 Ma, thus indicating there was a time interval of less than 15 Myr between the cessation of sedimentation and the occurrence of high-grade metamorphism. Metamorphic zircons have a range of ages, from ca. 2465 to 2415 Ma, consistent with a period of similar to 50 Myr during which high-grade metamorphism occurred. Mafic and felsic intrusions have ages that range from ca. 2520 Ma to 2460 Ma, indicating magmatism occurred during sedimentation and continued during the early stages of metamorphism and deformation of these rocks. The presence of bimodal magmatism with continental arc affinity (Devils Playground Volcanics) together with mafic intrusions showing temporal overlap with sedimentation within the Mulgathing Complex suggests that the overall tectonic regime prior to deformation likely involved lithospheric extension, possibly related to a continental magmatic arc. The Mulgathing Complex shows similarities in the nature and timing of these tectonothermal processes with several other Neoarchean-Paleoproterozoic terranes, in particular the Terra Adelie Craton in Antarctica, the Sask Craton, Canada, and regions within the North China Craton and the North Australian Craton. It is possible that similarities in process could imply along-strike relationships between these terranes, for example as laterally continuous terranes at the margin of a former continental domain (or domains). Basement rocks with ages of ca. 3250-3150 Ma, ca. 2950-2800 Ma and 2600-2550 Ma within the Gawler Craton, as inferred from magmatic and inherited zircons, are temporally equivalent to some of the main basement units within the Pilbara Craton, and basement rocks in both the Gawler and Pilbara cratons are overlain by sedimentary rocks at ca. 2480 Ma that include banded iron formations. It is possible to envisage the Gawler Craton as representing an extended continental margin adjacent to a larger, more intact continental domain, such as the Pilbara. (C) 2014 Elsevier B.V. All rights reserved.
机译：南澳大利亚州戈勒克拉通（Gawler Craton）内的马尔加辛（Mulgathing）复杂地带，其岩浆作用，沉积作用和变质作用的证据涵盖了新古代与古元古代之间的过渡（约2555-2410 Ma）。在这项研究之前，有限的数据可用来约束这些构造热事件的时间。我们报告说，Mulgathing矿床的变质沉积岩浆岩的SHRIMP锆石U-Pb测年表明，沉积沉积片麻岩（Christie Gneiss）具有最大的沉积年龄。 2480 Ma，与以前的研究相反，该研究表明大约在大约2月份发生了沉积。 2510马。我们数据中最古老的变质锆石约为。 2465 Ma，因此表明沉积停止与高级变质发生之间的时间间隔小于15 Myr。变质锆石的年龄范围从大约2465至2415 Ma，与发生高级变质的类似于50 Myr的时期一致。母体和长英质侵入的年龄范围从大约1到2。 2520 Ma至2460 Ma，表明岩浆作用发生在沉积过程中，并在这些岩石的变质和变形的早期持续。具有大陆弧亲缘关系的双峰岩浆作用（魔鬼游乐场火山）以及镁铁质侵入体表明Mulgathing复杂区内的沉积与沉积存在时间重叠，这表明变形前的整体构造体制可能涉及岩石圈扩展，可能与大陆岩浆弧有关。 Mulgathing复杂体在这些构造热过程的性质和时间上与其他几个新古宙古生代地层相似，特别是南极的Terra Adelie Craton，加拿大的Sask Craton以及华北克拉通和北澳大利亚克拉通内的地区。过程中的相似性可能暗示这些地层之间的沿走向关系，例如，作为前一个大陆域（或多个域）边缘的横向连续地层。约有年龄的地下岩。 3250-3150 Ma，约从岩浆和继承的锆石推断，高勒克拉通内的2950-2800 Ma和2600-2550 Ma在时间上相当于Pilbara Craton内部的一些主要基底单元，而Gawler和Pilbara克拉通的基底岩石被约有沉积岩2480 Ma，包括带状铁地层。可以将高勒克拉通（Gawler Craton）视为代表更大的，更完整的大陆区域（例如Pilbara）附近的扩展大陆边缘。 （C）2014 Elsevier B.V.保留所有权利。

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