Sedimentary Characteristics and Origin of Taitung Canyon in Eastern Waters of Taiwan Island

There is a lack of systematic discussion on the sedimentary characteristics and causes of Taitung Canyon. The morphological features, sedimentary filling characteristics and origin of Taitung Canyon are analyzed by using the single-channel and multi-channel seismic profiles recently acquired in eastern Taiwan. Taitung Canyon is mainly located in the Huatung Basin and is generally oriented NE oriented with a length of 160 km, a width of 0.2-14 km in the water depth of 4 000-5 500 m.The Taitung Canyon can be divided into three types in profile shape:V, U, complex types and three segments in plane:upper, middle and lower segments, which are NE-NEE-striking, NE-NNW-striking and NE-striking respectively. Mass movements such as slides or slumps are ubiquitous in the upper of Taitung Canyon, which are driven by a variety of erosional processes from gravity flow erosion to turbidity current. Wavy deposition can be observed in the flank of the middle section of Taitung Canyon, which may be formed by turbidity current. The sufficient deposits could be discharged at the lower of Taitung Canyon, where the modern submarine fan developed.The formation and development of the Taitung Canyon resulted from the interaction between the tectonic activity, topography and deep-water deposition. Upper segment is controlled by topography and deep-water deposition. Gravity flow deposition provides a material and power source for the erosion and fills in the canyon.The middle segment is controlled by tectonism, which Gagua Ridge changes the orientation of the middle reach of Taitung Canyon; The deep-water fan, located at the end of Taitung Canyon, is controlled by "trumpet" topography.When they get rid of the lateral constraints from Gagua Ridge, the debris occur to unload, resulting in a large deepwater fan.