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研究生:陳儀清
研究生(外文):Chern, Yi-Ching
論文名稱:臺灣西南外海海床表層沉積現象之研究
論文名稱(外文):Sedimentology of surface sediments off Southwest Taiwan
指導教授:陳民本陳民本引用關係俞何興俞何興引用關係劉家瑄劉家瑄引用關係陳琪芳陳琪芳引用關係周瑞燉周瑞燉引用關係鄭偉力謝昭輝謝昭輝引用關係
指導教授(外文):Chen Men-PenTian Wen-MinFan Zheng-ChengWang Joa-joaShiu Shea-jieWen Jeng-hwaLing Yu-Sung
學位類別:博士
校院名稱:國立臺灣大學
系所名稱:海洋研究所
學門:自然科學學門
學類:海洋科學學類
論文種類:學術論文
論文出版年:1997
畢業學年度:85
語文別:中文
論文頁數:180
中文關鍵詞:沉積學沉積構造角礫質泥岩生物擾動濁流泥火山
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本研究係對臺灣西南外海海床之五個箱型岩心及四十六支重力岩心進
行一系列的沉積 構造、粒徑、物理性質、有機碳和碳酸鈣的分析及含量
檢測,以瞭解當地之沉積環境。 研究結果顯示臺灣西南海域海床
表層沉積物可分成四個堆積區及六種沉積構造相: (1)陸棚區的陸源
碎屑堆積缺乏明顯之層理且含貝殼碎屑,為砂質混沌沉積構造,(2)河口
的陸源碎屑堆積區因受高屏溪季節性及氣候性之影響,形成紋層構造
,(3)角礫質泥岩堆 積區因泥火山之泥漿噴發活動,形成角礫泥岩的散
亂堆積構造,(4)在高屏斜坡上之沉積 大多屬於濁流堆積區,濁流堆積
區可再分為「不含黃鐵礦絲」及「含黃鐵礦絲」兩種構造 相。此外,陸
坡上的岩心及大部份的河口堆積區岩心中含有生物擾動的痕跡相當普遍,
呈 現含生物擾動的沉積構造。

整體而言,臺灣西南海域的沉積環境主要受到地體構造所控制。板塊的持
續隱沒、擠 壓促成泥貫入體的形成及發育,也造成地形崎嶇,峽谷、渠
道密佈。泥貫入作用在角礫泥 岩堆積區形成大規模的泥火山活動,其他
地區亦有零星泥火山的發現。部份角礫泥岩堆積 中夾雜濁流沉積構造,
證明泥火山有間歇性噴發活動。粒徑分析結果顯示壽山海渠與高屏 峽谷
為臺灣西南海域棚坡沉積物傳輸的主要管道,高雄峽谷雖在地形上較壽山
海渠更陡峭 而綿長,但並未擔負傳輸沉積物的主要角色。豐沛的陸源碎
屑沉積物藉由河川與沿岸的侵 蝕源源輸入大海,陸棚上的潮汐流及離岸
海流將沉積物向外海搬運,陸坡上沉積物的搬運 則以濁流為主。濁流中
大量的細顆粒沉積物附著有機碳沉降在陸坡之上,提供底棲生物所 需食
物,造成沉積物中普遍的生物擾動現象,並因而形成還原環境,使部份地
區在表層即 有黃鐵礦絲之形成。

在高屏斜坡上濁流的發生頻率相當高,在一個濁流事件尚未結束,水體中
尚存在許多 懸浮物時,另一個濁流事件可能又已發生,因而濁流的層序
重疊而不完整。在濁流的旁側 或其末端,有富含生物擾動及黃鐵礦絲之
半濁流沉積構造。本研究區沉積物中之黃鐵礦聚 集型態共可分為以下五
類:(1)桿狀,(2)近乎垂直之髮狀細絲,(3)斷續、凌亂之細絲或 細桿
,(4)獨立之細球粒或較大之團塊,(5)極細顆粒之霧狀聚集。生痕的存在
促成黃鐵礦 聚集成形。沉積速率及有機碳含量明顯會影響生痕的種類。
在臺灣西南大陸斜坡的岩心中 共發現十種生痕,其中含黃鐵礦絲堆積區
所含種類最多,濁流堆積區次之,河口陸源碎屑 堆積區最少,陸棚區則
未發現生物擾動痕跡。
Surface sediments from five box cores and forty-six gravity
cores in continental shelf and slope off southwestern
Taiwan were examined. Analyses of radiography, grain-size,
physical properties, and organic carbon as well as carbonates
contents of these sediments were performed to recognize the
sedimentary environments of the study area.

Four depositional subenvironments and six types of sedimentary
structures off southwestern Taiwan have been identified: (a)
terrigenous clastic shelf deposits with shelly sands; massive
structure, (b) terrigenous clastic estuary deposits off Kaoping
River; laminated structure, (c) mudstone brecciaed mudstone
deposits resulting from the eruption of mud volcanos; breccia
scattering structure, (d) turbidite sequence structure.
Turbidite deposits can be subdivided into two structures: pyrite
vein facies and non-pyrite vein facies. Bioturbation is commonly
found in core sediments from Kaoping slope and formed
bioturbated structure. In general, the
sedimentary environments of the continental shelf and slope off
southwestern Taiwan were controlled by tectonics. The plate
subduction and compression between Eurasian and Philippine Sea
plates contribute the formation and development of mud diapirs,
and make the rugged slope surface incised by many canyons and
gullies. In the subenvironment characterized by mudstone
brecciaed mudstone, mud diapirism contributes a large scale mud
volcano activity, but, some single mud volcano have also been
found in other subenvironments. Some mud breccia was interbeded
with turbidites suggesting intermittent eruptionof mud
volcanoes. On the basis of grain-size analysis, Shou-Shan Gully
and Kaoping Canyon were found to be the main passages of the
slope sediment transportation. Although the Kaohsiung Canyon is
deeper and much extensive than the Shou-Shan Gully, Kaohsiung
Canyon does not play the role for slope sediment transportation.
Abundant terrigenous clastic matierals continuously pour into
the shelf and slope area by river propagation and longshore
erosion. Tidal current and offshore current are the main
mechanism of shelf sediment transportation, while turbidity
current is that prevalent on the slope. Abundant fine-grained
sediments within the turbidity currents were attached by
organic carbon and were deposited on the slope, offering foods
for benthos. It is probably the reason that bioturbations can
be commonly found within the sediments in a reducing setting,
and even the pyrite vein can be formed in the surfacial
sediment. In Kaoping Slope, turbidity currents may occurr in
high frequency. Incomplete sequences of turbidites may be due to
overlapping turbidity events. Near the sides and at the end of
turbidites, hemiturbidite structure associated with abundant
trace fossils and pyrite veins can be found. Five types of
pyrite vein can be distinguished in the study area. Most of them
are trace fossil tracks and tubes filled with pyrite.
Obviously the diversity of trace fossilwas constrained by
sedimentary accumulation rate and the organic carbon content.Ten
species of trace fossils can be found from the sediments on
Kaoping Slope, where the pyrite vein (or hemiturbidite)
subenvironment has the highest diversity, turbidite
subenvironment the second, and estuary area the least.
Bioturbation is rarely found in the sediments on the shelf.
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