The Deep-seated Structures And Assembly Processes Of The Microcontinents In The Proto-tethy Ocean

The Proto-Tethys Ocean research has always been a hot and difficult scientificstudy of the Earth because of a series of unknown affinity micro-continental blocks inthe Proto-Tethys Ocean. For a long time, scholars usually reveal their affinities,formation and evolution on basis of shallow structures of these micro-continents orgeological outcrop in instead of the deep-seated information. However, geophysicalmethods have a good effect on revealing the deep information and the traditionalgeological methods generally do not reflect the deep-seated information. This thesisattempts to explore the deep-seated structures of micro-continental blocks to solve thisproblem.The deep-seated structure can be reflected by the Bugur gravity anomaly. It isprimarily characterized by alternation of uplift and depression. The gravity anomalywas caused by mantle depth difference in the study area. Anomalies nature isrelatively large difference in different regions, and it reflect the distribution ofmagmatic rocks and the crystalline basement metamorphic, by aeromagnetic dataprocessing. The basement of the study area was consisting of more than one block.Gravity data or aeromagnetic data can only do an initial discussion on themetamorphic basement because of the multiplicity of potential field method, but itslateral resolution is very high.It can make more accurate judgment about the lateralheterogeneity of the compositions and structures of the basements. At the same time,magnetotelluric detection and deep seimic sounding are considered credible methodsto reveal crustal structures. Therefore, the combination of geophysical data can revealthe deep-seated structures of the microcontinents in the Proto-Tethy Ocean. Anomalyof deep geophysical field is nearly NS-trending abnormal and state, while the uppercrust nearly east-west structure as the leading factor.Firstly, this thesis explores the plane distribution and the range of themicro-continental blocks through the analysis of gravity and magnetic anomaly data.Secondly, it explains the deep-seated information to divide the micro-continentalblocks in Proto-Tethys Ocean and determine their ancient subduction polarity through tomography method, contrasting magnetotelluric data and deep-seated reflectionseismic profiles. Finally, it collects the known chronology and geological informationto discuss their evolution.