A new interpretation of the high aeromagnetic anomaly zone in central Tarim Basin

Abstract：The ΔTa high aeromagnetic anomaly zone lying in the central part of Tarim Basin has been a focus in discussing the composition and structure of Tarim basin and its basement. Based on a comprehensive analysis of borehole and seismic data, the authors have found that there exist large-scale seismic reflection anomaly bodies in Middle-Upper Ordovician strata of Manjiaer depression, which are related closely to the Central High Aeromagnetic Anomalies Zone (CHAAZ) and constituted mainly by eight nearly EW-trending seismic reflection anomaly bodies. The stratigraphic and seismic facies analysis shows that these seismic anomaly bodies should be igneous rocks. The anomaly bodies have vertical downward channels in seismic profiles, which are related to faults and magmatic activity channels. The CHAAZ of the basin is a product of multi episodes tectonic activities, suggesting the development of Manjiaer depression in an extensional tectonic setting in Sinian and Late Ordovician.