Magnetic fabrics in characterization of magma emplacement and tectonic evolution of the Moyar Shear Zone, South India

Pratheesh, P.; Prasannakumar, V.; Praveen, K. R.

doi:10.1016/j.gsf.2012.04.004

Cited by 10 publications

(3 citation statements)

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“…The cooling and heating curve were irreversible, and the cooling curve showed conspicuous increase in susceptibility, corroborating the creation of new magnetite in the heating curve (Archanjo et al, 1999). In addition, the high values of mean susceptibility are normally interpreted to be contributed mainly by ferromagnetic phases (Rochette, 1987;Tarling et al, 1993;Pratheesh et al, 2013). According to thermomagnetic measurements and magnetic susceptibility, it is considered to be dominantly contributed by magnetite acting as main magnetic carrier of the sample with high value of susceptibility.…”

Section: Magnetic Mineralogymentioning

confidence: 76%

“…If the mean susceptibility value is comparatively lower, i.e. less than 500 µSI, it is interpreted to be dominantly contributed by paramagnetic phyllosilicate such as biotite acting as main magnetic carrier (Rochette, Table 1 Magnetic fabric data of the Jingzhuba-Shiwo section 1987; Tarling et al, 1993;Pratheesh et al, 2013). Additionally, the κ-T curve was controlled jointly by component and grain size distribution of magnetic minerals, which was relatively complicated to be deciphered, especially for the weak magnetic minerals (Ao et al, 2007).…”

Section: Magnetic Mineralogymentioning

confidence: 99%

“…The T parameter, called shape parameter, indicates the shapes of the susceptibility ellipsoids, varying from -1 (perfectly linear magnetic fabric) to +1 (perfectly planar magnetic fabric). And the P parameter is the corrected anisotropy degree, indicating the intensity of the preferred orientation of magnetic minerals in a rock (Pratheesh et al, 2013). Compared with Cartesian plot, a polar plot of T − P J gives an unbiased distribution of ellipsoid shapes, especially for those with low P J (Borradaile et al, 2010).…”

Section: T and P Jmentioning

confidence: 99%

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Magnetic Fabrics in Jingzhuba‐Shiwo Section of Foreland Fold Belt of the South Dabashan: Constraints on Its Tectonic Evolution

Xie

Zhang

Xiu-feng

et al. 2014

Chinese J of Geophysics

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A detailed investigation of the structural geometry and magnetic fabrics together with rock magnetism has been carried out along Jingzhuba‐Shiwo section located in the foreland fold belt of the South Dabashan, which aims to shed light on the superimposed deformation and tectonic evolution. As a whole, the intensity of deformation decreases from the northeast to the southwest, and the axial planes dip northeastward and the hinges of large‐scale folds plunge northwestward at small angle. Moreover, the maximum principal stress indicates that the compression of the South Dabashan is dominant as per palaeostress analysis. The sampling horizons before the Late Jurassic are mainly characterized by magnetic fabrics in deformed rocks, whereas the sampling horizons ranging from the Late Jurassic to the Early Cretaceous are characterized by incipient magnetic fabrics in weakly deformed rocks. The magnetic lineations are dominantly oriented NW‐SE and remain almost parallel to the main tectonic structures of the section, suggesting that AMS can be ascribed to tectonic processes. Also there are two types of unusual magnetic fabrics revealed. The first one merely occurring in the northeast section is characterized by an oblique magnetic foliation with respect to bedding, which is related with parallel‐bedding simple shear during fold growth. The other one caused by tectonic superimposition is characterized by an oblique magnetic lineation with respect to bedding strike. The plunges of Kmin increase with decreasing deformation intensity from northeast to southwest along the section, which can be taken as a gauge to distinguish the deformation intensity of weakly‐deformed sedimentary rocks according to the relativity. Consequently it can be concluded that the superimposed structure of the section was formed by the combined compression which arose from the South Dabashan primarily and the Micangshan and the eastern Sichuan fold belt secondly during the Late Jurassic. Afterwards the compression from the South Dabashan was still dominant, the compression from the other two directions, however, became much weaker in the Early Cretaceous than in the Late Jurassic. Furthermore, the effects resulting from Qinling intracontinental orogeny during J3‐K1 and Xuefeng intracontinental deformation could be reflected by the results mentioned above, which can also provide evidences for exploration of continental dynamics.

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Section: Magnetic Mineralogymentioning

confidence: 76%

Section: Magnetic Mineralogymentioning

confidence: 99%

Section: T and P Jmentioning

confidence: 99%

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