| 南盘江断陷区二、三叠系的火山碎屑浊积岩--一种独特的无海底扇浊流沉积模式 |
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| 引用本文： | 侯方浩,黄继祥.南盘江断陷区二、三叠系的火山碎屑浊积岩--一种独特的无海底扇浊流沉积模式[J].沉积学报,1984,2(4):19-32. |
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| 作者姓名： | 侯方浩 黄继祥 |
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| 作者单位： | 西南石油学院 南充 |
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| 摘 要： | 一、概况位于滇、黔、桂三省间的南盘江断陷区面积达十万平方公里以上,自下二叠统茅口阶顶部至下三叠统印度阶,除周边和区内的一些孤立的碳酸盐岩台地外,连续地沉积了一套火山碎屑浊积岩及其伴生的富含放射虫、硅质海绵骨针的硅质岩,区域上大致作北西向的南、北两带展布,延伸约400公里,宽30-60公里不等,并于三省交界处汇合(图1)。地层东薄西厚,以茅口阶顶部和上二叠统的火山碎屑浊积岩厚度为准,南带最东端出露于广西武鸣、灵马等地，仅厚7 0-100米，向西至百色阳坪厚200米左右，至田林八渡厚361.44米，至隆林岭芬厚673米，西林石炮厚675米，再西至贵州雄武厚910米，云南师宗花桂一号井厚达1400米以上3北苹情况类似，东端的广西南丹龙王坡厚不足100米，向西至拥里厚127米，再西至贵州乐康厚612米，紫云卡务厚796米。
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RESEARCH INTO THE PERMIAN AND TRIASSIC VOLCANICLASTIC TURBIDITE OF NANPAN RIVER SEG-A UNIQUE TURBIDITE MODE WITHOUT SUBMARINE FAN |
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| Institution: | South-western Petrpleum Institute |
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| Abstract: | Nanpan River seg is located in the junction of Yunnan, Guizhou and Guangxi Provinces and its area is about 100, 000 km2. Besides isolated carbonate platforms which are different in size and roughly distribute in the WE direction, a set of volcaniclastic turbidite and chemigenic or biochemigenic silicilith associated with it were extensively deposited in this area from late Maokou Stage to Early Triassic epoch. Its maximum thickness is up to 1, 400. There is still a dispute about the lithologic character, naming, distributive regularity, eruptive mechanism and depositional mechanism of the volcaniclastic turbidite and silicilith. On the basis of the results of the field and laboratory work over four years, the author has pointed out that it is a set of andesitic volcaniclastic turbidite that erupted along the rift belt on sea floor and belongs to an ash flow type. According to the regional distributive regularity of the section types of different lithologic fabrics it can be divided into three types. ( 1 ) Volcanic lasfic avalanche-turbidite type ( 2 ) Dust cloud-suspension depositional type ( 3 ) The super type of volcaniclastic turbidity current and calciclastic turbidity fan. Nanpan River seg was located in Yunkai-Wuyi back-arc expending belt in late Paleozoic epoch. On the folede basement of early Paleozoic epoch, the activity of the seg became so strong that the crust thinned and back arc was expending. Thus paleogeomorphologic prototype which showed the form of alternation of trenches with platforms revealed itself. Under the great influence of Dongwu movement, the basement rift movmeent in NW, NE and NS directions happened in this area and this paleostructure was formed from the graben type of trenches alternating with the carbonate platforms that belong to horst type. Soon after eruption and intrusion of basic magma, in the trenche,there frequently happened intermediate ash flow tuffs eruption and after the middle Triassic the whole area began to subside. Then the seg mainly received calciclastic gravity flow sediments that came from adjacent carbonate platforms and terrigenous clastic turbidity sediments from the east part of Yunkai Mountain. In addition, there was a bit of the turbidity sediments resulting from acidic magma eruption during early Ladinic stage. The regional strong folding of the second episode of Indo-China movements made the sedimentary depositional history come to end. Two types of turbidite without submarine fan were summarized by Walker (1978). The first is the exogeosynclinal situation, the second is in the predeltaic areas on the craton. Nanpan River seg was located in back-arc expending belt from late Maokou stage to Early Triassic epoch. Actually, the graben type trench in this area is an exogeosyncline. The difference between them consists in material source, turbidity sediments in this seg from ash flow type tuffaceous materials erupted in the trench. So it is a unique turbidite mode without submarine fan. |
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