Tectonic Dynamic Mechanism Of Tectonical-sensitive Elements’ Migration And Aggregation In Tectonically Deformed Coal

Tectonically deformed coal (TDC) samples with various deformation types andextents were collected from Huaibei Coalfield, and the migration and aggregation fortectonically sensitive elements in TDC were investigated, in combination with geologicalanalyzes of study region and dynamic mechanics of TDC development, distribution andmorphology of minerals in coal were analyzed, then the test methods of ICP-MS、SEM-EDX、XRF and CVAFS were used in the paper, the distribution and morphology ofminerals in coal, Major and trace and rare earth elements (REE) were determined, thenmigration and aggregation Characteristics for tectonically sensitive elements in TDCwere analyzed, finally their dynamic mechanics was revealed. The results were showedas follows:(1) Based on the structure and deformation mechanism, TDC from HuaibeiCoalfield can be systematically divided into6types and9classes, the distribution,deformation and morphology of minerals in TDC is related to tectonic deformation ofcoal, fissure filling, mechanical mixing and pressolution rheological effect are the mostimportant reasones.(2) The epigenetic mineral distribution characteristics and construction control werediscussed. Using the methods of XRD and SEM-EDX, the mineral distributioncharacteristics of TDC in Huaibei Coalfield were analyzed, found that with thedeformation degree increase of tectonic coal the crystallinity and integrity worse. Relatedto tectonic coal formation mechanism, fractures which formed in brittle deformationprocess provide the space for the formation and occurrence of minerals; coal deformationand dynamic metamorphism in ductile deformation process that driving elementmigration and aggregation and provide chemical conditions to mineral occurrence.(3) The migration and aggregation in different types of TDC were revealedsystematically. The distribution of major elements, organic elements, trace elements andrare earth elements were analyzed, elements migration accumulation associated withtectonic coal deformation degree, elements differentiation in different types of TDC andstructures, tectonic stress is a driving force prompt the elements migration andaccumulation.(4) The structure control mechanism of sensitive elements in different types of TDCwas revealed. We conclude that Xisipo thrust-nappe structures is a closed reductionenvironment, the elements migration, aggregation and loss in hanging wall and footwallof Xisipo Thrust-nappe Structure abide by the energy conservation law, the sensitive elements migration from high to low stress area which caused by regional tectonic stressand its associated with dynamic metamorphism; Sensitive elements in fault are changedregularly in upthrowns and downthrowns, the center is located in the fault surface. Withthe increase of tectonic coal deformation degree, dynamic metamorphism became themain factors to control element migration in coal, and influenced by the stress-strainenvironment and mechanical mixing action.(5) Basis on the basic law of sensitive elements migration and aggregation, theselecting principle and method of tectonic stress sensitive elements in TDC wasestablished, then the stress sensitive elements in different TDC types and differenttectonic position were selected, that provides a new way to establish a tectonicgeochemical method to predict coal and gas outburst.(6) The stress sensitive element migration accumulation dynamics mechanism wasdiscussed systematically. The results showed that the elements migration process includemigration and accumulation process then aggregation in favorable parts of structure,There are both physical and chemical approaches to prompt the migration process.Including five kinds of migration accumulation mode: fracture filling, stress and dynamicthermal migration, force chemistry, mechanical mixing rheological and so on. Tectonicaction after coal-formation, brittle or ductile deformation, and the metamorphicmechanism and its accompanying dynamic thermal effects are the main factors thatinfluence the redistribution of elements in TDC. We conclude that tectonic movementsprovide the motivation and basis for the redistribution of elements and the paths andmodes of element migration are controlled by brittle and ductile deformationmetamorphic processes. The dynamic thermal effect has the most significant effect oncoal metamorphism and tectonic-stress-accelerated element migration and accumulation.These factors then induce the tectonic-dynamic differentiation phenomenon of elementmigration.