福建漳州盆地活动断裂研究

本文从形态学和运动学的角度,确定并系统地研究了二十条主要活动断裂。北西向断裂以正-左行走滑型为主,北东向断裂以右行走滑-逆断层为主,两组断裂构成活动断裂网络。用 C¹⁴年龄数据计算得到了最近5990—1870年以来,各取样点地壳平均升降速率的变化范围是+3.53mm/a 至-0.65mm/a。用布仑法求得的九龙江活动断裂现代平均滑动速率是1.7mm/a。更新世至现代构造应力场的最大主压应力是以缓倾角、走向为 NW290°左右为特征的。350m 深处最大主压应力是700—760bar。两组断裂交汇形成的高渗透率带,对形成对流型中、低温热水型热田是十分有利的。此外,对该区的地震活动性亦进行了讨论。

THE RESEARCH ON ACTIVE FAULTS IN ZHANGZHOU BASIN, FUJIAN PROVINCE

Based on the systematic collection and analysis of geological and geomorphologic evide- nces, seismic events, bore hole data, geophysical data and coordinating the satellite images and airphotographes, the twenty active faults were studied in Zhangzhon Basin. These faults are high angle at the bedrock outcrop aad buried under the basin, and characterised by the network of intersection with NW aad NE trending faults which are the reaction of pre-existing faults or further developed fractures. Since Late-Pleistocene, Zhangzhou Basin was divided into up and down fault-blocks by active faults, controlling the development of Quaternary de posits and landforms. The NW faults and NE faults are prevalently normal sinistral strike-slip and dextral strike-slip reverse faults, respectively.Radiocarbon data of eleven samples representing different fault-blocks suggest that the average rates of tectonic uplift or submerge range from +3.53mm/yr to -0.65 mm/yr during 5990-1870 years.The maximum principal compressive stress directions of the tectonic stress field from Pleistocene to recent are mainly characterised by about NW 290? with low angle and also obtained by eighteen measurred points of the latest active conjugate shear joints and twenty five focal mechanism solutions. The recent maximum principal compressive stress at 350 m depth is 700-760 bars by means of acoustic emission method.The NW faults with extension and extension-shear, especially, the intersection of NW and NE trending faults, are favourable for low enthalpy hot-water systems. Sugar refinery-Gutang area is the most favourable area for forming low enthalpy hot-water system.That NW trending faults were more active than NE trending faults is proved through establishing a model of pre-existing NW and NE trending faults under the recent tectonic stress field. Fengle village-Guanyin mount fault and Guanyin mount-Fugong fault may be se-ismogenic faults in the future 100-200 years, but there will be less danger within the coming 50 years.