Newly found Tunglo Active Fault System in the fold and thrust belt in northwestern Taiwan deduced from deformed terraces and its tectonic significance

We found active faults in the fold and thrust belt between Tunglo town and the Tachia River in northwestern Taiwan. The surface rupture occurred in 1999 and 1935 nearby the study area, but no historical surface rupture is recorded in this area, suggesting that the seismic energy has been accumulated during the recent time. Deformed fluvial terraces aid in understanding late Quaternary tectonics in this tectonically active area. This area contains newly identified faults that we group as the Tunglo Fault System, which formed after the area's oldest fluvial terrace and appears at least 16 km long in roughly N–S orientation. Its progressive deformations are all recorded in associated terraces developed during the middle to late Quaternary. In the north, the system consists of two subparallel active faults, the Tunglo Fault and Tunglo East Fault, striking N–S and facing each other from opposite sides of the northward flowing Hsihu River, whose course may be controlled by interactions of above-mentioned two active faults. The northern part of the Tunglo Fault, to the west of the river, is a reverse fault with upthrown side on the west; conversely the Tunglo East Fault, to the east, is also a reverse fault, but with upthrown side on the east. Both faults are marked by a flexural scarp or eastward tilting of fluvial terraces. Considering a Quaternary syncline lies subparallel to the east of this fault system, the Tunglo Fault might be originated as a bending moment fault and the Tunglo East Fault as a flexural slip fault. However, they have developed as obvious reverse faults, which have progressive deformation under E–W compressive stress field of Taiwan. Farther south, a west-facing high scarp, the Tunglo South Fault, strikes NNE–SSW, oblique to the region's E–W direction of compression. Probably due to the strain partitioning, the Tunglo South Fault generates en echelon, elongated ridges and swales to accommodate right-lateral strike–slip displacement. Other structures in the area include eastward-striking portion of the Sanyi Fault, which has no evidence for late Quaternary surface rupture on this fault; perhaps slip on this part of Sanyi Fault ceased when the Tunglo Fault System became active.     

Role of the Kazerun fault system in active deformation of the Zagros fold-and-thrust belt (Iran)

Field structural and SPOT image analyses document the kinematic framework enhancing transfer of strike-slip partitioned motion from along the backstop to the interior of the Zagros fold-and-thrust belt in a context of plate convergence slight obliquity. Transfer occurs by slip on the north-trending right-lateral Kazerun Fault System (KFS) that connects to the Main Recent Fault, a major northwest-trending dextral fault partitioning oblique convergence at the rear of the belt. The KFS formed by three fault zones ended by bent orogen-parallel thrusts allows slip from along the Main Recent Fault to become distributed by transfer to longitudinal thrusts and folds. To cite this article: C. Authemayou et al., C. R. Geoscience 337 (2005).     

Tectonic evolution of an active tectonostratigraphic boundary in accretionary wedge: An example from the Tulungwan-Chaochou Fault system,southern Taiwan

The Tulungwan-Chaochou Fault system in southern Taiwan represents the boundary between a slate belt of moderate metamorphic grade and a relatively unmetamorphosed fold-and-thrust belt. The offset between hanging wall and footwall of this fault ranges from 7 to 11 km and is considered one of the major tectonostratigraphic faults in Taiwan. This 75-km-long fault system is also one of the most conspicuous topographic features in Taiwan. The geometry, kinematic history and associated subsidiary structures have not been resolved. Field mapping of fabrics and brittle faults show that a 45-km-long west-northwest-vergent antiform defined by folded slaty cleavage exists in the hanging wall of the fault. This antiform has not been previously described and apparently formed in a brittle environment. The flat crest and tight forelimb of the antiform suggests a two-stage deformation model composed of a fault-bend fold followed by a trishear fold. We infer that regional scale fold is associated with a thrust that splays upward from the main detachment.     

胶西北焦家断裂带成矿后断裂活动对焦家式金矿破坏作用及找矿方向探讨

本文以焦家断裂带深部上盘发现金矿体的地质事实为依据,将焦家断裂在成矿后对矿体的破坏作用作为讨论重点,根据现今焦家断裂上、下盘金矿体以断层泥为界,有被错断的明显特征,指出发育在焦家断裂主断裂面中的断层泥为成矿后断裂活动的产物.依据上、下盘金矿在矿石类型、围岩蚀变、矿石矿物、成矿阶段等方面具有极为相似一致特征,提出在117...