Palaeomagnetic, geochronological and geochemical study of Mesoproterozoic Lakhna Dykes in the Bastar Craton, India: Implications for the Mesoproterozoic supercontinent
Palaeomagnetic, geochronological and geochemical study of Mesoproterozoic Lakhna Dykes in the Bastar Craton, India: Implications for the Mesoproterozoic supercontinent
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DOI：
10.1016/j.lithos.2012.07.015
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发表时间：
2013-08
期刊：
影响因子：
3.5
通讯作者：
S. Pisarevsky;T. K. Biswal;Xuan‐Ce Wang;B. Waele;R. Ernst;U. Söderlund;J. Tait;Kamleshwar Ratre;Y. K. Singh;Mads Cleve
中科院分区：
文献类型：
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作者：
S. Pisarevsky;T. K. Biswal;Xuan‐Ce Wang;B. Waele;R. Ernst;U. Söderlund;J. Tait;Kamleshwar Ratre;Y. K. Singh;Mads Cleve
Lakhna 岩脉（印度巴斯塔克拉通）的古地磁分析得出古极点位于北纬 36.6°，东经 132.8°，dp=12.4°，dm=15.9°，从其中一个流纹质岩脉获得的 UPb 锆石年龄为 1466.4±2.6Ma（MSWD=0.21，基于协和年龄）两次分析具有相同的 Pb/U 年龄），与之前发表的 UPb 年龄类似。 Lakhna Dykes 的主量和微量元素分析表明，钾玄岩和高钾钙碱性亲和力与俯冲相关特征一致，表明存在活跃的大陆边缘环境。这与印度东部边缘古至中元古代的构造环境相符。新的1460Ma印度古极点被用来测试印度在中元古代哥伦比亚超大陆内可能的古位置。在四个古地磁允许的重建中，将印度西部与波罗的海西南部并置是地质上最可靠、最合适的模型。我们首选的重建意味着一个长的古元古代到中元古代增生造山带，从劳伦大陆东南部穿过波罗的海西南部延伸到印度东南部。印度和波罗的海的分裂可能发生在中元古代晚期，但还需要额外的限制。
Palaeomagnetic analysis of the Lakhna Dykes (Bastar Craton, India) yields a palaeopole at 36.6°N, 132.8°E, dp=12.4°, dm=15.9°, and the UPb zircon age obtained from one of the rhyolitic dykes is 1466.4±2.6Ma (MSWD=0.21, concordia age based on two analyses with identical Pb/U ages), similar to previously published UPb ages. Major and trace element analyses of the Lakhna Dykes show shoshonitic and high-K calc-alkaline affinities consistent with a subduction related characteristics suggesting an active continental margin setting. This is in keeping with the Palaeo- to Mesoproterozoic tectonic environments in the eastern Indian margin. The new 1460Ma Indian palaeopole was used to test possible palaeopositions of India within the Mesoproterozoic supercontinent Columbia. Of the four palaeomagnetically permissible reconstructions, juxtaposing western India against south-west Baltica is geologically the most reliably constrained and best fitting model. Our preferred reconstruction implies a long Palaeo- to Mesoproterozoic accretionary orogen stretching from south-eastern Laurentia through south-western Baltica to south-eastern India. Breakup of India and Baltica probably occurred in the Late Mesoproterozoic, but additional constraints are needed.