An analysis of crustal magnetic anomaly and Curie surface in west Himalayan syntaxis and adjacent area

Abstract

In this paper, the magnetic model NGDC-720-V3 is used to investigate the distribution of crustal magnetic anomaly and the depth of Curie surface in west Himalayan syntaxis and its adjacent area. The Curie surface is compared with regional heat flow, the Moho, and seismicity. The results show that the magnetic anomaly and Curie surface are both consistent with the regional tectonic setting. Tarim craton, Tadjik Basin, and Indian Plate have positive magnetic anomaly and a Curie surface deeper than 36 km, corresponding to low heat flow there. In contrast, orogenic belts such as west Himalayan syntaxis, Tianshan Mountain, Afghanistan, and Tibetan Plateau have negative anomaly and a Curie surface shallower than 32 km, corresponding to high heat flow. The north of the syntaxis presents a positive anomaly on the surface, resulting from Ferghana Basin, while the negative anomaly in large depth is probably associated with the subduction of the slab and the resulting heat. The depth of the Curie surface has an inverse relationship to the Moho depth, which is attributed to temperature and isostatic balance. The distribution of earthquakes with epicenter deeper than 100 km clearly suggests the subduction of the Indian plate deep down to the asthenosphere and the deep earthquakes were caused by shear motion within the subducting slab.

Studies on the relationships of the Curie surface with heat flow and crustal structures in Yunnan Province, China, and its adjacent areas

“…The geothermal method is based on geothermal data of terrestrial heat flow, geothermal gradients, and thermal conductivity. Its disadvantage is that it cannot directly measure the geothermal parameters at a relatively large depth (Gao et al 2017(Gao et al , 2018Tanaka et al 1999). There are many factors that affect the depth of a Curie surface, including the surface heat flow, the geothermal gradient, the rock heat generation rate, mantle heat flow, fault activity, and the composition of rock physical properties.…”

Sources of the lithosphere magnetic field based on magnetic data obtained at different heights

“…The methods applied for identification of magnetic anomaly sources are mainly based on the results of spectral analysis of their data. The method described in Spector and Grant (1970) is widely used for estimating the depths of geological objects (Gao et al 2017;Tanaka et al 1999), which will be considered in "Spectral analysis" section of this paper.…”

Correlation between lithospheric magnetic anomalies and tectonic structures in the Norwegian-Greenland region of the Arctic

“…Таким образом, поскольку магнитное поле индуцируется магнитными минералами в коре и верхней мантии, его параметры могут использоваться как маркер для определения структуры литосферы [Hemant, Maus, 2005]. АМП, отражающее современное положение тектонических структур и их физические свойства, может быть использовано для расчета параметров земной коры, в частности для расчета поверхности изотермы Кюри [Gao et al, 2017]. Опираясь на данные об АМП, можно оценивать площадное распределение погруженных проводящих коровых слоев, ассоциированных с шовными зонами внутри и на периферии древних кратонов, выявлять зоны платформенной активизации, а также изучать геодинамические процессы в активных регионах -выделять глубинные разломные зоны и «корневые» области частичного плавления в верхней мантии [Hemant, Maus, 2005;Abramova et al, 2017].…”