Magnetic polarity of Masol 1 locality deposits, Siwalik Front Range, northwestern India
Résumé
The Mio-Pleistocene Siwalik formations have been known worldwide since the 19th century for their fossil hominoids. Numerous paleomagnetic studies have contributed to build the chronological framework of the Siwalik Group subdivided into Lower, Middle and Upper Siwalik Subgroups. Our study concerns the Tatrot Formation (Late Pliocene) of the Upper Siwalik Subgroup located at Masol in the Chandigarh Siwalik Frontal Range (India), and is accessible by the Patiali Rao River. At Masol (district Mohali, Punjab), the erosion of the anticline structure has formed an inlier and exposed paleontological assemblages characterizing the Late Pliocene “Quranwala fossiliferous zone”. Since 2008, the Indo-French research program, “Siwaliks”, has conducted surveys in the Masol inlier and has collected stone tools on the surface of the outcrops among fossilized bones, a few with cut marks. The first cut-marked bone was discovered in 2009 at Masol 1 (M1). The study of the magnetic polarities of some stratigraphic units of M1 revealed that the deposits recorded a normal polarity. According to the paleontology and the previous magnetostratigraphy of the Patiali Rao, it appeared that the deposits of Masol 1 are older than the Gauss-Matuyama reversal, dated to 2.58 Ma.