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Middle cretaceous geomagnetic field anomalies in the eastern Indian Ocean and their implication to the tectonic evolution of the Bay of Bengal

DRS at CSIR-National Institute of Oceanography

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Title Middle cretaceous geomagnetic field anomalies in the eastern Indian Ocean and their implication to the tectonic evolution of the Bay of Bengal
 
Creator Desa, M.
Ramana, M.V.
 
Subject Geology and geophysics
Geology and geophysics
Geology and geophysics
 
Description The Middle Cretaceous period is largely known for its stable normal polarity in the Earth's magnetic field. A few reversals (ISEA, M-3r; M-2r and M-1r) have been postulated during this period but are yet to be accepted in total. Recently, two anomalies Q1 (92 Ma) and Q2 (108 Ma) have been identified globally and proposed as internal time markers useful to trace the evolution of the world oceans. While the evolutionary history of the Indian Ocean from Late Cretaceous to present is well-established, the older (Middle to Early Cretaceous) record is still ambiguous. The occurrence of a major plate reorganization during the Middle Cretaceous period has added to the dilemma in understanding the early evolution of the Eastern Indian Ocean. The detailed evolution of the Bay of Bengal and its conjugate Enderby Basin has remained speculative to date due to various constraints such as lack of good geophysical dataset and drill sites, and the presence of thick sedimentary load. In the present study, an attempt is made to validate the occurrence of the Middle Cretaceous internal time markers in the Eastern Indian Ocean. These time markers are used to provide additional constraints for tracing the evolution of the Eastern Indian Ocean since Late Jurassic. Identification of these markers aided to confirm the timing of spreading ridge extinction in the Perth Basin as 102 Ma. In the Bay of Bengal, these markers facilitated to infer the evolution of the Middle Cretaceous crust, east of the buried 85°E Ridge. The age of the oceanic crust increases from south to 115 Ma at the northern tip of the Bay of Bengal. Seafloor spreading occurred in ~ NNE-SSW direction between 115 Ma and 102 Ma, and thereafter it changed its direction to ~ N-S. Half spreading rates ranging from 4.0 to 4.2 cm/yr between 108 Ma and 84 Ma in the Bay of Bengal are higher than its conjugate Enderby Basin. This spreading system belongs to the second rifting episode between Antarctica and India, and was caused by the Kerguelen mantle plume activity. The 85°E Ridge south of 12°N is emplaced on a transform fault that constitutes the northern extension of the 86°E Fracture Zone and active since 102 Ma. The study suggests that excess crustal accretion occurred on the Indian plate since the Middle Cretaceous
 
Date 2016-12-02T11:52:13Z
2016-12-02T11:52:13Z
2016
 
Type Journal Article
 
Identifier Marine Geology, vol.382; 2016; 111-121
no
http://drs.nio.org/drs/handle/2264/5053
 
Language en
 
Relation Mar_Geol_382_111.jpg
 
Rights An edited version of this paper was published by Elsevier. Copyright [2016] Elsevier
 
Publisher Elsevier