Rodinia refined or obscured: palaeomagnetism of the Malani igneous suite (NW India)

被引:299
作者
Torsvik, TH
Carter, LM
Ashwal, LD
Bhushan, SK
Pandit, MK
Jamtveit, B
机构
[1] Univ Lund, Dept Geol, S-222333 Lund, Sweden
[2] Rand Afrikaans Univ, Dept Geol, ZA-2006 Auckland Pk, South Africa
[3] Geol Survey India, Jaipur 302004, Rajasthan, India
[4] Univ Rajasthan, Dept Geol, Jaipur 302004, Rajasthan, India
[5] Univ Oslo, Dept Geol, N-0316 Oslo, Norway
基金
新加坡国家研究基金会;
关键词
Rodinia; Neoproterozoic; Malani igneous suite; India; palaeomagnetism; palaeogeography;
D O I
10.1016/S0301-9268(01)00139-5
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
New palaeomagnetic data from the Neoproterozoic felsic volcanic rocks of the Malani igneous suite (MIS) in NW India, combined with data from an earlier study, yield a palaeomagnetic pole with latitude = 74.5 degreesN, longitude = 71.2 degreesE (dp/dm = 7.4/9.7 degrees). A statistically positive fold test and remanences carried by typical high-temperature oxidation (deuteric) minerals support a primary magnetic signature. U/Pb ages from MIS (771-751 Ma) overlap with those for granitoids and dolerite dykes from the Seychelles microcontinent (mainly 748-755 Ma), and palaeomagnetic data for both entities can be matched with a tight reconstruction fit (Seychelles --> India: Euler latitude = 25.8 degreesN, longitude = 330 degreesE, rotation angle = 28 degrees). In this Neoproterozoic time interval, MIS and the Seychelles must have been located at intermediate northerly latitudes along the western margin of Rodinia, with magmatism that probably originated in a continental are. The most reliable, dated palaeomagnetic data (+/- 756 Ma) from MIS, Seychelles and Australia require a crucial reappraisal of the timing and plate dynamics of Rodinia break-up and Gondwana assemblage. These new data necessitate an entirely different fit of East Gondwana elements than previously proposed, and also call to question the validity of the Southwest US-East Antarctic and Australia-Southwest US models. The palaeomagnetic data mandate that Greater India was located west of Australia rather than forming a conjugate margin with East Antarctica in the hlid-Neoptroterozoic. Break-up of Rodinia along western Laurentia may therefore have taken place along two major Neoproterozoic rifts: one leading to separation of Laurentia and Australia-East Antarctica, and the second between Australia and India. (C) 2001 Elsevier Science B.V. Ah rights reserved.
引用
收藏
页码:319 / 333
页数:15
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