台灣位在歐亞板塊與菲律賓海板塊的聚合交界帶上，在這活躍的地體架構下，台灣有著較多的聚合作用。台灣西南部包括台南、高雄及屏東，在外海及陸上都有發現泥貫入體(Mud diapir)以及泥火山(Mud volcano)等構造。為了了解西南海域泥貫入體和泥火山，本研究使用涵蓋台灣西南海域的重力資料和多頻道反射震測等地球物理資料，來分析探討台灣西南部的泥貫入體及泥火山的關係。 我們使用了OR1-1009及OR1-1030航次的重力資料以及多頻道反射震測，再利用重力資料進行模擬與多頻道反射震測相互比對。在模擬中，本研究以有根泥貫入體模型（深度1-2公里）及無根泥貫入體模型（深度10公里）來進行模擬，可以得到結果是在Line2以西，以有根泥貫入體模擬較好，以東則是以無根泥貫入體模擬較好。之後以重力異常值來比對，可以得到在有泥火山區域的泥貫入體，重力異常值呈現負的異常。在密度對比上約在0.4 g/cm3 ～ -0.3 g/cm3之間，而有噴氣活動的泥火山區，密度對比約在0 g/cm3～ -0.3 g/cm3之間。 Taiwan orogeny is located in a convergent zone between the Eurasian Plate and the Philippine Sea Plate. Because of initial collision, there are folds and thrusts off SW Taiwan. Besides, there are mud diapirs and mud volcanoes in the onshore and offshore area of SW Taiwan. In this study, we use the gravity data and seismic data to study the density anomalies of the mud diapers. We use the gravity data and seismic data collected in OR1-1009 and OR1-1030 cruises. According to those data, we find that mud diapers are basically formed by relatively low-density material in the middle of the diapirs. The relatively low density may be due to the gassy and hydrous sediments. In this study, we use two gravity models to simulate the mud diapirs: (1) a mud diaper model of 10 km thick (root model) and (2) a mud diaper model of 1-2km (non- root model). In the west of Line 2, the root model is better than the non-root model. In the east of line 2, the non-root model is better than the root model. In general, the density contrast of a mud diapir is about 0.4 ~ -0.3g/cm3 and a mud volcano is about 0 g/cm3 ~ -0.3 g/cm3.
