深圳后海填海区北西向隐伏断层的综合探测研究

Comprehensive Exploration of the Northwest Buried Faults in theHouhai Reclamation Area, Shenzhen

在现场地质调查基础上,通过钻探、断层气氡探测、浅层地震探测和智能微动探测等多种手段,揭示深圳后海填海区隐伏断层F1、F2的几何学特征,对沿北西向断层发育的风化槽成因进行分析。结果表明:1)F1、F2隐伏断层发育于燕山期花岗岩中,走向、倾向和倾角分别为N38°~40°W、NE、59°~63°和N50°W、NW、70°,断层带宽分别为30~35 m、40 m,主要由碎裂岩及碎斑岩组成,裂面上发育薄层碎粉岩,绿泥石化现象显著,属脆性破裂体系,均为张性兼反扭性质,未见扰动全新世地层;2)采用断层气Rn浓度强度对隐伏断层相对活动性进行测定显示,F1隐伏断层活动性较强;3)F1、F2断层分别控制风化槽南西、北东边界,风化槽主要成因为张性断层上盘较下盘破碎,裂隙、孔隙和次级小断层较发育,构造破碎的花岗岩体在海水、温度等作用下使长石快速风化所致。

Based on the geological survey,through drilling,fault gas radon detection,shallow seismic detection and intelligent micro-motion detection,we reveal the geometric characteristics of buried faults F1 and F2 in the Houhai reclamation area of Shenzhen,and analyze the weathering genesis of the NW trending faults.The results show that:1)The buried faults F1 and F2 are developed in Yanshanian granite,and the occurrences are N38°-40°W,NE,59°-63°and N50°W,NW,70°,respectively.The width of the faults are 30-35 m and 40 m,respectively.Cataclasite rocks can be widely found around the faults and the chlorite phenomenon is obvious as well.A thin layer of powdery rock is developed in the fault surface zone,but the overlying Quaternary strata is not disturbed.The faults belong to brittle fracture system and present both tensile and reverse torsional features.2)The relative activity of the buried faults are measured by fault gas Rn concentration intensity,which shows that the relative activity of F1 buried fault is strong.3)F1 and F2 faults control the southwest and northeast boundaries of the weathered trough respectively.The main causes of the weathered trough are that the hanging wall of the extensional fault is more cataclastic compared to the lower wall,the cracks,pores and secondary faults are denser,and the rapid weathering of feldspar in broken granite under the action of water and temperature.