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Research On The Tectonic Boundary Of Ying-Qiong Basin And Adjacent Faults’Features Based On Gravity And Magnetic Data

Posted on:2014-04-19Degree:MasterType:Thesis
Country:ChinaCandidate:J A ZhangFull Text:PDF
GTID:2250330422461316Subject:Solid Earth Physics
Abstract/Summary:PDF Full Text Request
Ying-Qiong basin(Yinggehai basin&Qiongdongnan basin)locates in the position-jointof Indosinian Block and South China Continent. With complex geological structure, theregion is at the confluence of strike-slip and extensional continental margins in thenorthwestern of the South China sea,and it’s also the extrusion-escape tectonic area ofIndia-Australian and Eurasian plate collision,and the subduction-stretch tectonic zone ofPaleo-South China sea. Yinggehai basin is located in the northwest edge of the south Chinasea, which is the growth of the red river fault zone in sea area, and is a Cenozoicconversion-extensional basin formed under the dual action of lithosphere extension and thered river fault zone strike-slip; Qiongdongnan basin is located in the marginal sea andcontinental transition zone, is a passive continental rift basin of typical double-layer structurewith fault and depression. It is universally acknowledged that No.1fault is the northernboundary of Ying-Qiong basin. However due to the lack of geological and geophysical data inthe southern part, the tectonic framework in this area and the location of the southern tectonicboundary of Ying-Qiong basin are not explicit. Based on widely collected geological andgeophysical material including terrain data, satellite gravity, aeromagnetic and petrophysical,and after the gravity and magnetic data processing we research characteristics of the gravityfield and magnetic field in the boundary of Ying-Qiong basin. The key technology of dataprocessing include bouguer gravity anomaly calculation, vertical derivative calculation, thenormalized vertical derivation of total horizontal derivative calculation, reduction to polecalculation with variational inclination in low magnetic latitude and corresponding analysisbetween gravity and magnetic data. we realize that there is an obvious gravity and magneticanomaly belt to the north of the boundary of Ying-Qiong basin,and the belt is just in theposition of No.1fault. There is an obvious zone with higher value of gravity and magneticanomaly, which we deduced “Zhongjian rise”. And using the technology based oncorrespondence analysis of gravity and magnetic anomalies, we ascertained the range of therise. We recognized the faults near the boundary of Ying-Qiong basin using the technologybased on the normalized vertical derivative of the total horizontal derivative (NVDR_THDR)for gravity and magnetic anomaly data. NNW-trending faults are primarily distributed in itswest, and NE-trending in the east. With the comprehensive research on geological andgeophysical data, we conclude that the northern boundary of Ying-Qiong basin is the No.1fault;“Zhongjian rise” is the southern boundary, it is take the role of structural transformation belt during the formation and evolution of the Ying-Qiong basin, and is the boundary ofstrike-slip and stretching marginal intersection zone in the northwest of South China sea too.
Keywords/Search Tags:boundary of Ying-Qiong basin, faults, Zhongjian rise, the normalizedvertical derivative of the total horizontal derivative (NVDR_THDR), technology based oncorrespondence analysis of gravity and magnetic anomalies
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