Preliminary geological interpretation of long-wavelength magnetic anomalies over China and surrounding regions

Abstract

Long-wavelength (>500 km) magnetic anomalies originating in the lithosphere were first found in satellite magnetic surveys. Compared to the striking magnetic anomalies around the world, the long-wavelength magnetic anomalies in China and surrounding regions are relatively weak. Specialized research on each of these anomalies has been quite inadequate; their geological origins remain unclear, in particular their connection to tectonic activity in the Chinese and surrounding regions. We focus on six magnetic high anomalies over the (1) Tarim Basin, (2) Sichuan Basin (3) Great Xing’an Range, (4) Barmer Basin, (5) Central Myanmar Basin, and (6) Sunda and Banda Arcs, and a striking magnetic low anomaly along the southern part of the Himalayan-Tibetan Plateau. We have analyzed their geological origins by reviewing related research and by detailed comparison with geological results. The tectonic backgrounds for these anomalies belong to two cases: either ancient basin basement, or subduction-collision zone. However, the geological origins of large-scale regional magnetic anomalies are always subject to dispute, mainly because of limited surface exposure of sources, later tectonic destruction, and superposition of multi-phase events.

Keywords

• long-wavelength magnetic anomaly
• lithospheric magnetic anomaly
• lithospheric magnetic field model
• satellite magnetic survey
• cses