Paleomagnetism of some Gondwana red beds from central India

Abstract

Oriented samples were collected for paleomagnetic research from red horizons of the Gondwana sediments at a few localities in central India. The specimens were subjected to both alternating-field and thermal demagnetization and were measured on astatic magnetometers. Usually a stable direction of magnetization was observed only after thermal treatment. The following results were obtained: 1. (1) The Upper Permian Kamthi Beds reveal a mean direction of magnetization given by D = 79.4°, I = +61.6° (pole position 21.05°S 50.4°W; dp = 2.8° and dm = 3.7°); 2. (2) The Lower Triassic Mangli Beds have D = 100.1°, I = +62.8° (pole position 7.3°S 55.7°W; dp = 5.7° and dm = 7.3°); 3. (3) The Upper Triassic Pachmarhi Beds have D = 117.2°, I = +48.9° (pole position 10.15°N 49.9°W; dp = 4.0° and dm = 6.1°). These results combined with earlier data indicate that the Indian subcontinent has made a sinistral rotation of about 90° during Upper Paleozoic through Mesozoic times, without a considerable meridional shift.