کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10145001 | 1646331 | 2018 | 61 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
An assembly of the Indian Shield at c. 1.0â¯Ga and shearing at c. 876-784â¯Ma in Eastern India: Insights from contrasting P-T paths, and burial and exhumation rates of metapelitic granulites
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Recent studies indicate that the Indian Shield formed contemporaneously but separately from Rodinia in Late Mesoproterozoic-Early Neoproterozoic. However, assembly of the eastern Indian Shield is poorly constrained. The dominant WSW-ENE â¼1.0â¯Ga foliation in Central Indian Tectonic Zone (CITZ) including Chotanagpur Gneissic Complex (CGC) in Eastern India indicates a north-south collision between the Northern and Southern Indian Blocks (NIB and SIB). But in northeastern CGC, the dominant foliation is north-south and parallel to the Eastern Indian Tectonic Zone (EITZ), a linear N-S to NNE-SSW belt associated with sinistral shearing at â¼876-784â¯Ma along the eastern margin of CGC, in Elan Bank of Kerguelen Plateau, and possibly in East Antarctica. The youngest dates in the metapelitic granulites from EITZ and NE-CGC (>13â¯km west of EITZ) are â¼876-784â¯Ma and â¼1.0â¯Ga, respectively. But monazite crystallization depends on bulk composition, and it is unclear whether the N-S foliation in NE-CGC metapelites originated at â¼1.0â¯Ga or â¼876-784â¯Ma. Pseudosection analysis in the MnO-CaO-Na2O-K2O-FeO-MgO-Al2O3-SiO2-H2O-P2O5-Y2O3-Ce2O3-F system shows contrasting P-T paths for the metapelites of NE-CGC (clockwise with <7â¯kbar/700â¯Â°C to â¼14â¯kbar/825â¯Â°C prograde conditions) and EITZ (counterclockwise with 8.93â¯kbar/794â¯Â°C to 8.80â¯kbar/809â¯Â°C prograde conditions, loading to 10.22â¯kbar/777â¯Â°C, and isothermal decompression to 6.83â¯kbar/787â¯Â°C). Furthermore, garnet diffusion modeling indicates that the burial rate (3.5-8.4â¯km/Ma) was similar to the exhumation rate (2.2-7.2â¯km/Ma) in NE-CGC, whereas exhumation (15-27â¯km/Ma) was â¼8-25 times faster than burial (1.1-2.0â¯km/Ma) in EITZ. The N-S foliation in NE-CGC is a manifestation of a â¼1.0â¯Ga collision between the CGC and Dinajpur Block along the EITZ, and is similar to the N-S trend in the NIB-Marwar Block collision zone in northwestern India. Evidently, SIB collided northward with NIB, NIB collided westward with Marwar Block, and Dinajpur Block collided westward with NIB simultaneously at â¼1.0â¯Ga. The EITZ was reactivated by sinistral shearing at â¼876-784â¯Ma, when the Dinajpur Block moved northward. In Cretaceous, dextral strike-slip movement on the E-W Dauki Fault split the Dinajpur Block into its present configuration. The northern parts of NIB and Dinajpur Block collided with Asia in Cenozoic during Himalayan Orogeny.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Precambrian Research - Volume 317, October 2018, Pages 117-136
Journal: Precambrian Research - Volume 317, October 2018, Pages 117-136
نویسندگان
Nilanjan Chatterjee,