Deep electrical signatures across the Achankovil shear zone, Southern Granulite Terrain inferred from magnetotellurics

作者：Naidu G Dhanunjaya^*; Manoj C; Patro P K; Sreedhar Sreejesh V; Harinarayana T

来源：Gondwana Research, 2011, 20(2-3): 405-426.

DOI：10.1016/j.gr.2010.12.002

• Achankovil shear zone
• Magnetotellurics
• Deep resistivity structure
• Collision zone
• Flower structure

Two parallel magnetotelluric (MT) traverses across the Achankovil shear zone (AKSZ) in southern India using a wide band (1 kHz-1 ks) data acquisition system, reveal the regional geo-electric average strike direction of N 40 degrees W, consistent with the geological strike direction of the AKSZ. The derived model shows distinct high electrical resistivity (> 1000 Omega m) for the upper crust below the Madurai Granulite Block (MGB) with a gentle dip towards south and a northerly dip below the Kerala Khondalite Block (KKB). The lower crust is resistive below both MGB and KKB while it is moderately conductive (< 500 Omega m) below AKSZ. Our study shows that the AKSZ is a tectonic divide between the MGB to the north and KKB to the south. The results together with an integration of seismic, gravity and heat flow data suggest a high dense and moderately conductive mantle material brought up to the mid-lower crust, and a thermally eroded crust with a flower structure at depth, in conformity with the model of AKSZ as the trace of a collisional suture.

• 出版日期2011-9