Review of Researches on the Magnetic Quiet Zone at the Northern Continental Margin of the South China Sea and Its Comparison with Those in the Global Oceans

Abstract

Different from the magnetic lineations in oceans,magnetic quiet zone(MQZ),where magnetic anomalies are greatly subdued in amplitude with long wavelengths,also probably contains information of tectonic activities and evolutions from continental margin rifting to sea floor spreading.In order to deepen understanding in the MQZ at the northern continental margin of the South China Sea,this paper summarized three possible occurrences of the global MQZs originated from physical,chemical and structural processes,respectively,located at marginal zones and abyssal zones of the global oceans,mainly Jurassic MQZs both in the Atlantic and the western Pacific,Cretaceous MQZs in the northern Pacific,the Indian and in the Southern.Meanwhile,it is worth attaching importance to mantle plume activities in different scales,small magnetic sources induced by initially fragmented ridge oblique to the continental margin and faint magnetic lineations in those MQZs.And then,main advances of study of the MQZ at the northern continental margin of the South China Sea have been analyzed,and mechanisms of the MQZ formation have also been discussed from views of both regional integrated geophysics and mantle thermal activities.Finally,research emphases and their significances are clarified to catch attention for the MQZ.