Magnetic susceptibility and facies relationship in Bajocian–Bathonian carbonates from the Azé caves, southeastern Paris Basin, France

Abstract

AbstractThis study focuses on three Bajocian and Bathonian carbonate sections from the southeastern part of the Paris Basin (Mâconnais area, in the east of France). The main goals of the study are to propose a palaeoenvironmental model, to get insight into vertical and lateral facies evolution, to improve correlations and to better understand the origin of the magnetic susceptibility (MS) signal in these deposits. The sedimentological setting corresponds to a ramp, with two types of geometries: (1) a homoclinal carbonate ramp with oolitic shoals; and (2) a multiple-slopes carbonate ramp with reef complexes. The MS signal appears to be influenced by facies and ramp geometry. The evolution of MS seems to be mainly related to changes in carbonate productivity and water agitation: oolitic facies and reef complexes, with high carbonate production show the lowest signal, while storm deposits are characterized by higher values. In addition, the MS signal from proximal tempestites have higher values than distal ones. MS appears to be a useful complementary proxy for palaeoenvironmental interpretations, correlations and sequential stratigraphy. The facies evolution, supported by MS curves, shows at least nine successive depositional sequences, which were inserted into the regional sequential canvas.