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Title: | 臺灣北方海域新近紀的盆地演化 The Neogene Basin Development Offshore Northern Taiwan |
Authors: | Eason Yicheng Yang 楊懿丞 |
Advisor: | 劉家瑄(Char-Shine Liu) |
Keyword: | 臺灣北方海域,前陸盆地,盆地演化模型,多頻道反射震測,構造特徵, Offshore northern Taiwan,foreland basin,basin development model,multi-channel reflection seismic data,post-collision extensional collapse and structural features., |
Publication Year : | 2017 |
Degree: | 碩士 |
Abstract: | 本研究經由多頻道反射震測資料及井位資料對臺灣北方海域的構造及盆地特徵進行分析,提出臺灣北方海域盆地的演化模型。配合井位資料的對比以及地質架構的分析,我們得到三個區域性的地層邊界,分別為:中中新世前陸盆地基底面,上新世前陸盆地沉積物底覆面(downlap surface),以及上新世垮塌不整合面。本研究描繪出台灣北方海域構造的邊界與範圍,認為位於金山北方外海的外金山斷層為一重要地質邊界。在外金山斷層以東,有一系列東北-西南向的正斷層出現,可分別對比臺灣北部陸上的基隆斷層、崁腳斷層、臺北-深澳坑斷層、龍洞斷層、屈尺-澳底斷層。在外金山斷層以西,我們辨識出數個頂部遭到傾蝕的背斜與斷塊,而在此區西緣有向西進覆之反射層序,再往西,向西進覆的反射層序趨向水平。以褶皺-逆衝帶與前陸盆地演化的觀點,可將向西進覆之反射層序、受到傾蝕的背斜斷塊以及活化正斷層的斷塊視為垮山之前的前陸盆地沉積區、原逆衝區(proto-thrust zone)以及覆瓦狀逆衝區(imbricated-thrust zone)。因此外金山斷層為垮塌作用之重要地質構造,或為一垮塌前緣(front)。根據以上分析結果結合井位資訊,我們認為此區域盆地演化的模型一共經歷了五個階段:(1)後張裂盆地時期:此時期的地層形成於前陸基底面形成之前,表示此區構造尚未經歷弧陸碰撞的影響。(2)初始前陸盆地時期:初始臺灣造山帶於此時期形成,前陸基底面伴隨著初始臺灣造山帶荷重而撓曲形成。(3)成熟期前陸盆地時期:初始臺灣造山帶於此時期趨向成熟。在地層層序中,此時期的地層形成於前陸沉積物進覆面之後,其沉積物供應來源主要來自於初始臺灣造山帶。(4)造山抬升與侵蝕的穩定態(static state)期:在此階段中,盆地持續接收來自造山帶的沉積物,而在造山帶側,區域性的侵蝕發生,初始臺灣造山帶被傾蝕截切,留下一區域性侵蝕面。(5)後碰撞伸張盆地時期:此時期發生於區域性侵蝕截切之後,在地層中出現一系列反轉構造特徵,說明此區域在經歷擠壓後,再次進入伸張的應力環境。 We investigate the structural features and the Neogene basin development in the offshore northern Taiwan. Integrating multi-channel reflection seismic data with well data, we observe three regional sequence boundaries: Middle Miocene unconformity, Pliocene downlap surface, and Pliocene-Pleistocene unconformity, indicating the formation of foreland basin, the fulfillment of foreland basin, and the erosion of foreland basin and orogeny, respectively. We find the outer Chinshan fault which situated at the offshore area of Chinshan faults is the major structural boundary. It separates two regions from study area. On the east side of outer Chinshan fault, a series of normal faults trend NE-SE, and they can correlate to the fault onshore of Chilung fault, Kanchiao fault, Taipei-Shenaokeng fault, London fault, and Chuchin-Audi fault. On the west side of outer Chinshan fault, numerous truncated anticlines and fault blocks are identified. In addition, this region is dominated by the westward progradational reflection, which become flat-lying westward. In the perception of foreland and fold-thrust couplet model, we interpret the westward progradational reflection, the anticlines, and the reactivated fault blocks as the foreland basin, proto-thrust zone, and imbricated-thrust zone, formed in response to the early Taiwan orogeny before the mountain have collapsed. When the orogeny began to collapse, the outer Chinshan fault became the frontal structure of mountain collapse. According to the analysis above integrated with the drilled well data, we suggest there are five stages in the basin development. The tectonics in study area are dominated by basin rifting events, and is terminated by Oligocene-Miocene post-rift unconformity. Subsequently, compressional event began to occur and accreted wedge stared to form. The flexual forebulge is likely to occur in response to loading of accreted wedge. The flexual forebulge was eroded once it uplifted, forming the foreland basal unconformity. With the progradation of the accreted wedge, the mountain belt has become larger, becoming as a major sediment supplier. The sediments originated from orogenic belt sink into the foreland basin, forming the downlap surface. Subsequently, a regional erosion occurred in Pliocene, and the Orogenic belt was eroded, forming a regional erosion boundary. The erosion boundary reflects the age of post-collisional extension tectonic scenarios. The last, a post-collisional extension occur, forming a series of post-collisional extensional basins in study area. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/67746 |
DOI: | 10.6342/NTU201701534 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 海洋研究所 |
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