- 學位論文
菲律賓民多羅造山帶的剝蝕歷史
Exhumation History of The Mindoro,Philippine and Its Implication for Mountain Building Process.
摘要
菲律賓民多羅島位於呂宋島弧中段，處於菲律賓活動帶與巴拉望陸塊碰撞造山帶中，根據前人研究得知: 因始新世中國南海的開裂，造成巴拉望陸塊向南東遷移，並在中新世開始與菲律賓活動帶產生碰撞。 民多羅島的北邊主要分成兩塊變質岩帶，這兩塊變質岩形成主因由在侏羅紀時期Izanagi板塊的隱沒碰撞在亞洲大陸之下後，因為逆衝將Izanagi板塊的材料帶回地表經過變質，而形成後來的Halcon Metamorphics。隨即在始新世晚期到漸新世因亞洲大陸的拉張，導致巴拉望地塊(包含Halcon Metamorphics)向東南遷移。在Halcon變質岩區旁為低變質度的Lasala Formation，因Lasala Formation屬於大陸地殼來源，說明了其成因為一旁的Halcon Metamorphics在大陸地殼拉張的過程中沉積而形成的地層。 由於在民多羅島南部發現上新世邦索礫岩(Punso conglomerate)的沉積，藉此可推測南方碰撞造山運動的時期。但對於民多羅島北方尚未全盤了解情況下，本論文採用核飛跡定年法來加以釐清民多羅島的造山運動時間點與抬升剝蝕歷史。 民多羅島北部主要分成東西兩塊不同的變質岩帶，斷層走向則以東北-西南為主。另外在島的東側則是一條貫穿全島的民多羅斷層(Mindoro fault)，本研究工作則在此斷層上盤採集矽質片岩、變質砂岩、片麻岩等露頭為主要樣本，進行鋯石核飛跡定年，結果均約略為4~6個百萬年。 由於研究結果顯示民多羅島北部東西兩側變質岩，鋯石核飛跡定年結果皆約落在4~6個百萬年間，推測此年代應反映為巴拉望陸塊與呂宋島弧碰撞造山的時間點。根據前人研究，民多羅島南部的造山運動時間點約在上新世期間。結合以上可以推測:民多羅島全島的碰撞造山運動的時間點在6個百萬年左右，且島之東西或南北造山運動時間點均一致。
並列摘要
The Philippine Mindoro is located in the most southern edge of the Manila Trench.The seismic data in study area showing the subduction of the South China Sea lithosphere along the Manila Trench with extremely high depth; Due to this collision in PMB(Philippine Mobile Belt)formation of the Mindoro orogens. The work presented in this research is the dating result carried out in the Philippine Mindoro. Rock samples were collected around the island especially northeast and northwest part of Mindoro. A combination of fission track dating technology was applied in an effort to get better insight into various aspects in respective areas. The fission track ages on the plate of the major fault in east side Mindoro were around 6 Ma. Indicated the begging of collision in PMB even earlier. Although ,the information here is empty. Except the major fault in east side of Mindoro Metamorphic, we also found few faults with north-east trend in northwest part of Mindoro by dating result and topographic data. In the future, we will combine zircon U-Th/He with apatite fission track dating result to analysis the orogenic mechanism of Mindoro.