Study on Distribution Features of Crustal Magnetic Anomalies Around Eastern Himalayan Syntaxis

Abstract

AbstractThe Potsdam Magnetic Model of the Earth (POMME6.2) is used to investigate the spatial distribution of crustal magnetic anomalies around eastern Himalayan syntaxis and their decay with altitude. In order to study the different scales of magnetic anomalies, the two‐dimensional wavelet transform method is employed to decompose the ground magnetic anomalies. The relationship between magnetic anomaly and geological structure is also discussed. The results show that the distribution of crustal magnetic anomalies over study area is considerably non‐uniform. Relatively strong negative magnetic anomalies are distributed over Himalaya‐Eastern Syntaxis‐Longmen Mountains‐Daba Mountains, whereas positive magnetic anomalies are present over Sichuan Basin, with weaker magnetic anomalies over other regions. The eastern Himalaya syntaxis has important impact on magnetic anomalies around. All crustal magnetic anomalies over Eastern Syntaxis and the surrounding regions are medium‐ and short‐wavelength positive/negative ones superposed onto a negative or weak magnetic anomaly setting. These meso‐ and micro‐scale magnetic anomalies are generated from magnetic materials in the upper and middle crust, with strikes basically consistent with geological structures. Along Jinshajiang‐Honghe Fault Belt, there is a sharp weak magnetic anomaly belt. Longmenshan Fault Belt, Lijiang‐Xiaojinhe Fault Belt and Honghe Fault Belt are transitional zones between strong and weak magnetic anomalies. The east‐west magnetic anomalies in the central Tibetan Plateau exhibited arc shape in the dome of Eastern Syntaxis. The banded lumpy magnetic anomalies over the central Tibetan Plateau and Central Yunnan massif have the same decay rule.