Crustal evolution of the Southern Granulite Terrane, south India: New geochronological and geochemical data for felsic orthogneisses and granites
Crustal evolution of the Southern Granulite Terrane, south India: New geochronological and geochemical data for felsic orthogneisses and granites
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DOI：
10.1016/j.precamres.2014.01.007
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发表时间：
2014-06
影响因子：
3.8
通讯作者：
S. Brandt;M. Raith;V. Schenk;P. Sengupta;C. Srikantappa;A. Gerdes
中科院分区：
文献类型：
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作者：
S. Brandt;M. Raith;V. Schenk;P. Sengupta;C. Srikantappa;A. Gerdes
本文介绍了印度南部麻粒岩地体的长英质正片麻岩和花岗岩的 LA-ICPMS U-Pb 锆石和 U-Th-Pb 独居石年龄以及地球化学数据，印度南部麻粒岩地体是重建晚新元古代冈瓦纳超大陆演化的关键区域。这些数据确定了马杜赖省（南部麻粒岩地体的主要部分）的两个不同的地壳域，我们为它们的地壳演化提出了一个新的大地构造模型。西马杜赖域广泛由新太古宙晚期 (2.53–2.46 Ga) 俯冲相关的镁砂岩末岩组成，这些岩体在古元古代早期 (2.47–2.43 Ga) 麻粒岩相变质作用和部分熔融过程中被改造。马杜赖东部地区以巨大的表壳序列为主，该序列沉积在晚古元古代 (1.74–1.62 Ga) 的镁质长辉岩和 Hbl-Bt 片麻岩基底上，这些片麻岩是通过底层太古宙岩石的改造而形成的。马杜赖省的这两个地区都被大量的新元古代中期 A 型辉长岩和长英质正片麻岩 (0.83–0.79 Ga) 侵入，它们是在拉张裂谷的主要阶段将太古宙岩石改造为古元古代岩石以及少量的隐色辉长岩和流纹岩而形成的。区域新元古代中期（0.82–0.78Ga）变质作用在时间和空间上与A型花岗岩岩浆作用有关。新元古代晚期（约 0.55 Ga）这两个区域的汇聚在沿着超高温变质岩 SSW-NNE 走向的卡巴姆超高温带（Kambam UHT Belt）碰撞时达到顶峰，并与淡色花岗岩（0.56 Ga）的局部侵位相关。太古宙达尔瓦克拉通马杜赖省的增生最早发生在沿莫亚尔-巴瓦尼-高韦里缝合线的古元古代，这是一个独特的地壳区域，以新太古代晚期 (2.50 Ga) 俯冲相关的镁质末咬岩为特征。它们的年龄和成分与西马杜赖域的 charno-enderbites 相似，并侵入中太古宙 charnockites (2.85 Ga) 和变碱岩，代表洋壳的残余物。缝合带与西马杜赖域同时代，受到早古元古代 (2.49–2.45 Ga) HP 麻粒岩相变质作用的影响。正如马杜赖省一样，缝合带被新元古代中期（0.84 Ga）变花岗岩侵入，但仅局部受到早寒武世叠印（0.54 Ga）的影响。推断的达尔瓦尔克拉通马杜赖省的早古元古代增生以及大量中新元古代 A 型霞岩岩的伸展相关起源很难与最近建立的克拉通和马杜赖省之间的新元古代俯冲带和缝合带的概念相匹配。在古地理模型中，广泛的新太古宙西马杜赖域与马达加斯加中部的塔那那利佛域，而元古代东马杜赖域与东高止山脉最南端的翁戈莱域和斯里兰卡的万尼杂岩相连。
This article presents LA-ICPMS U-Pb zircon and U-Th-Pb monazite ages and geochemical data for felsic orthogneisses and granites from the Southern Granulite Terrane of India, a key area for reconstructing the evolution of the late-Neoproterozoic Gondwana supercontinent. The data identify two distinct crustal domains in the Madurai Province, the major part of the Southern Granulite Terrane, and we present a new geotectonic model for their crustal evolution. The Western Madurai Domain is widely composed of late-Neoarchaean (2.53–2.46 Ga) subduction-related, magnesian charno-enderbites, which were reworked in the early-Palaeoproterozoic (2.47–2.43 Ga) during granulite facies metamorphism and partial melting. The Eastern Madurai Domain is dominated by a vast supracrustal sequence, which was deposited on a late-Palaeoproterozoic (1.74–1.62 Ga) basement of magnesian charnockites and Hbl-Bt gneisses that formed through reworking of underlying Archaean rocks. Both domains of the Madurai Province were intruded by voluminous mid-Neoproterozoic A-type charnockites and felsic orthogneisses (0.83–0.79 Ga), which formed through reworking of Archaean to Palaeoproterozoic rocks, together with minor leuco-gabbros and rhyolites, during a major phase of extensional rifting. Regional mid-Neoproterozoic (0.82–0.78 Ga) metamorphism is temporally and spatially related to A-type granite magmatism. Convergence of the two domains in the late-Neoproterozoic (ca. 0.55 Ga) culminated in their collision along a SSW-NNE-trending belt of ultrahigh-temperature metamorphic rocks, the Kambam UHT Belt, and was associated by the localized emplacement of leucogranites (0.56 Ga).Accretion of the Madurai Province at the Archaean Dharwar Craton occurred in the earliest Palaeoproterozoic along the Moyar-Bhavani-Cauvery Suture, a distinct crustal domain characterized by late-Neoarchaean (2.50 Ga) subduction-related, magnesian enderbites. They resemble the age and composition of the Western Madurai Domain charno-enderbites and intrude Mesoarchaean charnockites (2.85 Ga) and metabasites, representing remnants of oceanic crust. The suture zone was, coeval with the Western Madurai Domain, affected by early-Palaeoproterozoic (2.49–2.45 Ga) HP granulite facies metamorphism. Just as the Madurai Province the suture zone was intruded by ferroan mid-Neoproterozoic (0.84 Ga) metagranitoids but was only locally affected by an early-Cambrian overprint (0.54 Ga). The inferred early-Palaeoproterozoic accretion of the Madurai Province at the Dharwar Craton and the extension-related origin of the voluminous mid-Neoproterozoic A-type charnockites are difficult to match with the recently established concept of a Neoproterozoic subduction zone and suture between the craton and the Madurai Province.In a Palaeogeographic model the widely Neoarchaean Western Madurai Domain is correlated with the Antananarivo Domain of central Madagascar, whereas the Proterozoic Eastern Madurai Domain is linked with the Ongole Domain, the southernmost segment of the Eastern Ghats Belt, and the Wanni Complex of Sri Lanka.