Deformation And Metallogenic Prediction Of Caohekou Area , Liaodong Peninsula

The Jiao-Liao-Ji orogenic belt,which records the tectonic messages of the North China Craton?NCC?from the Paleo-Proterozoic to present,is one of the most important tectonic belts and a valuable metallogenic zone in the eastern part of the NCC.Therefore,characteristics of deformation the Jiao-Liao-Ji orogenic belt are the key to understand the tectonic evolution and mineralizing processes in the eastern margin of the NCC.This study aims at analysis of structural deformation and metallogeny of the Caohekou area within the Jiao-Liao-Ji orogenic belt based on the previous researches,combining with our mew macro-and micro-deformation.Following new results are achieved in this study:Four deformation stages have been identified in study area.The first stage of extensional tectonics along N-S direction is characterized by penetrative foliation?schistosity?S₁,bedding-parallel recumbent folds,folded layers within ductile shear zone,mineral stretching lineations and boudinages.The second stage of continuous compression along S-N direction is characterized by synclines and fold-related faults,crenulation cleavages,kink bands,syn-tectonic quartz veins,axial cleavages dip to N or S,mica fishes and other related structural features.The third one of NE-trending compression characterized by superposition of synclines,and the cleavages dip to NW.The fourth stage is characterized by NW-trending strike-slip faults.The occurrences of the Caohekou syncline is rebuilt by measurement of the structural elements and cross-sections.The fold shows an interference pattern of cylindrical folds of S-N plunging upright fold over NW plunging upright fold based on three sections cross-cutting the Caohekou fold.The fold hinge up westward and down eastward,and the axis curve in 3-D space,the dip angle of axis changes from 32°to 15°then to 13°eastward.Regionally,the western segment has combination style of anticline-syncline-anticline,while,the eastern segment changes to a single syncline,and thus the middle segment is a transition zone for the assemblage style.The structural features of syncline and ore-forming geological characteristics of adjacent ore-concentration are studied.Based on the comprehensive analysis,it is suggested that there is a tectonic-metallogenic favorable area in the Caohekou syncline,which is probably located in the core of the Caohekou syncline,and in the triangular belt of interbedded fracture structure zone between the Caohekou fault and Jiaojiapuzi fault.