Detrital zircon U-Pb geochronology of the Eocene to Pliocene Series in central Taiwan: Implications for source provenance and exhumation history

• Main Authors: Hsien-Yuan Chou, 周賢元
• Other Authors: Wen-Shan Chen
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/68841602653829555873

碩士 === 國立臺灣大學 === 地質科學研究所 === 101 === Detrital zircons collected from sedimentary rocks can find out exhumation history for the U-Pb dating. This study aims to reconstruct the Eocene–Miocene exhumation history of the southeast China by using U-Pb detrital zircon geochronology. The samples were collected from the Eocene-Miocene formation along the Beigang river and the upper Miocene formation from the Daan river. Each sample contains about 80-100 zircons U-Pb dating data with LA-ICPMS. Zircon formed from igneous activity or metamorphism of the source province. U-Pb dates are distributed to several groups according to the major geological movement in southeast China, (1) Wutai orogeny (2400-2600 Ma) (2) Luliang orogeny (1700-1900 Ma) (3) Sibao orogeny (930-1000 Ma) (4) Jinning orogeny (700-850 Ma) (5) Caledonian orogeny (400-450) (6) Indosinian orogeny (200-250 Ma) (7) Early Yanshanian orogeny (200-145) (8) Late Yanshanian orogeny (Ⅰ) (100-145 Ma) and (9) Late Yanshanian orogeny (Ⅱ) (100-65 Ma) (10) continental rifting period (65-8Ma). Age spectrum analyses of the Eocene formation indicates that the major proportion is the Late Yanshanian orogenyⅠgroup, about 12%－22%； the major proportion of the Oligocene formation is the Late Yanshanian orogenyⅠgroup, about 23%－36%； the major proportion of the Miocene formation is the Luliang movement group about 10%－23%. The Major proportion of Yanshanian orogeny (Ⅰ) group shows the increasing in the Eocene to the Oligocene formations, but the decreasing in the Miocene formation means that Late Yanshanian orogeny (Ⅰ) period rock eroded and reduced the exposed area during the Miocene period； The Luliang movement group proportion of Miocene formation data is increasing, and it means that the younger rocks eroded causes older rocks exposed. The youngest zircon age can be a corroboration of sedimentary age of sedimentary rock, 39.3±0.8 Ma of the Eocene formation, 27.4±0.6 Ma of the Oligocene formation, 26.7±0.6 Ma of the Miocene formation that confirms the previous reports of the age of sedimentary rocks. Keywords: Central Taiwan, detrital zircon, U-Pb datimg