当前位置: X-MOL 学术Geolog. J. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Geochemistry of 2.21 Ga giant radiating dyke swarm from the Western Dharwar Craton, India: Implications for petrogenesis and tectonic evolution
Geological Journal ( IF 1.8 ) Pub Date : 2021-03-01 , DOI: 10.1002/gj.4109
Pooja Yadav 1, 2 , Drona Srinivasa Sarma 1, 2
Affiliation  

The Western Dharwar Craton (WDC) exhibits numerous exposures of NNW–SSE to NW–SE trending mafic dykes. Geochemistry of four 2.21 Ga NNW–NW trending dykes and 21 other similar trending dykes provides new insights into the geochemical behaviour, mantle source characteristics, and tectonic history of mafic magmatic event, which have also affected the Eastern Dharwar Craton (EDC). Based on modal mineralogy and texture, these dykes can be classified into dolerite, olivine dolerite, gabbro, and olivine gabbro. They show basaltic to basaltic-andesitic composition and have sub-alkaline tholeiitic nature. LaN/LuN ratio classifies the dykes into two groups: Group I, with values close to 2, shows relatively flat REE patterns while, Group II, with values 4–6, has inclined REE patterns. In general, both groups show LREE enrichment and most of the samples exhibit negative Nb–Ta and Ti anomalies, indicating crustal contamination. However, negative Zr–Hf anomaly and low Th/Nb values (0.14–0.73) noticed within the samples preclude significant crustal inputs. Petrogenetic modelling using batch melting equation suggests that the dykes fractionated from two distinct mantle melts and had slightly different sources, both within the spinel–garnet transition zone. The overall composition of these 2.21 Ga dykes is consistent with a mantle plume-induced heterogeneous source that was previously modified by some ancient subduction event. Coeval dykes from EDC exhibit similar geochemical behaviour, mantle source characteristics, and tectonic history. These and other synchronous dykes from distant cratons, viz. Superior, Slave, Greenland, represent a 2.21 Ga large igneous province event, which is linked with the Sclavia/Superia supercraton.

中文翻译:

印度西达尔瓦克拉通 2.21 Ga 巨型辐射堤群的地球化学:对岩石形成和构造演化的影响

西达尔瓦克拉通 (WDC) 显示出大量的 NNW-SSE 暴露于 NW-SE 走向的基性岩脉。四个 2.21 Ga NNW-NW 走向岩脉和 21 个其他类似走向岩脉的地球化学提供了对基性岩浆事件的地球化学行为、地幔源特征和构造历史的新见解,这些岩浆事件也影响了东达尔瓦克拉通 (EDC)。根据模态矿物学和质地,这些岩脉可分为辉绿岩、橄榄石辉长岩、辉长岩和橄榄辉长岩。它们显示玄武岩至玄武岩-安山岩组成,并具有亚碱性拉斑岩性质。La N /Lu N比率将岩脉分为两组:I 组,值接近 2,显示相对平坦的 REE 模式,而 II 组,值为 4-6,具有倾斜的 REE 模式。总的来说,两组都显示出轻稀土元素富集,并且大多数样品显示出负的 Nb-Ta 和 Ti 异常,表明地壳污染。然而,样品中注意到的负 Zr-Hf 异常和低 Th/Nb 值 (0.14-0.73) 排除了重要的地壳输入。使用分批熔融方程的岩石成因模型表明,岩脉从两个不同的地幔熔体中分馏出来,来源略有不同,都在尖晶石-石榴石过渡带内。这些 2.21 Ga 岩脉的整体组成与地幔柱诱导的非均质源一致,该源先前被一些古老的俯冲事件修改过。来自 EDC 的同期岩脉表现出类似的地球化学行为、地幔源特征和构造历史。这些和其他来自遥远克拉通的同步岩脉,即。苏必利尔、斯拉夫、格陵兰岛代表 2.21 Ga 大型火成岩省事件,它与 Sclavia/Superia 超克拉通有关。
更新日期:2021-03-01
down
wechat
bug