| 鄂尔多斯盆地东胜东三叠系—侏罗系湖泊风暴沉积的发现及其意义 |
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| 引用本文： | 钟建华,倪良田,孙宁亮,郝兵,薛纯琦.鄂尔多斯盆地东胜东三叠系—侏罗系湖泊风暴沉积的发现及其意义[J].沉积学报,2021,39(2):353-373. |
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| 作者姓名： | 钟建华 倪良田 孙宁亮 郝兵 薛纯琦 |
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| 作者单位： | 中国矿业大学(北京)煤炭资源与安全开采国家重点实验室,北京 100083;中国石化集团胜利石油管理局博士后科研工作站,山东东营 257000;中国石油大学(华东)地球科学与技术学院,山东青岛 266580 |
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| 摘 要： | 鄂尔多斯盆地东北部东胜—纳林河一带出露的中生界三叠系—侏罗系—白垩系地层，为一套河湖相沉积（白垩系可能有风成沉积）。在三叠系—侏罗系地层中发育完好的风暴沉积和风暴岩。在东纳林煤矿—德胜西岔路口的109国道两侧长约40 km的三叠系—侏罗系地层中发育风暴沉积，该德胜西剖面连续长度达548 m。这套风暴沉积主要为一套河流—三角洲—湖泊沉积（有少量泥炭沼泽），并以发育典型的风暴沉积构造:丘状构造（Hummocky Structures，HS）、洼状构造（Swaley Structures，SS）、丘状交错层理（Hummocky Cross Stratification，HCS）和洼状交错层理（Swaley Cross Stratification，SCS）极为引人注目。初步研究认为，这套风暴沉积和风暴岩主要发育在浅水湖泊中。主要特点:1）凡发育有风暴沉积或风暴岩的地方，地层的成层性极差，地层多呈透镜状、豆荚状或波浪状；2）岩层的接触关系主要为冲刷面，很少正常沉积接触，冲刷面呈不规则波浪状，最大起伏可达2 m；3）丘状和洼状构造具有连续的正弦曲线的完美形态，规模在中大型，波长在数米到近百米，高数十厘米到1~2 m；4）岩性及其组合主要为一套黄褐色砾岩+砂岩+灰色泥岩；具有明显的二元结构（下粗上细；下部块状上部发育层理）；在以粗碎屑为主的风暴沉积中砾岩是常见的底部沉积。在纳林煤矿附近有煤层形成的风暴沉积和风暴岩；5）在德胜西岔路口的重要剖面的风暴沉积和风暴岩底部发育了1~3层较厚的砾石层，其中中间一层为厚数十厘米到1~2 m，砾石直径大者可达30~40 cm，大部分具有叠瓦构造，前者可能指示了向湖的风暴回流，后者指示了向岸的冲洗流，揭示了风暴冲洗流非常强劲；6）灰色含砾块状泥岩，砾石呈漂浮状，揭示含砾泥岩是风暴冲洗流形成的类似于泥石流的快速沉积，而非正常天气形成的静水沉积；厚数十厘米的含砾泥岩揭示了当时的沉积速率相当大，也揭示了风暴流极其浑浊，可能几乎接近饱和；7）振荡流占优势，但在某些部位又具有明显的复合流和振荡流特点。8）总体沉积背景是一种宽阔浅水湖泊环境，以原地振荡垂向沉积为主。鄂尔多斯盆地三叠系—侏罗系湖泊风暴沉积是一种新的沉积类型。到目前为止，还未见到有关如此大型的HCS和SCS的相关报道。研究表明，形成这种风暴沉积的水体的最大深度在50 m左右。鄂尔多斯盆地早三叠世—中侏罗世的风暴沉积和风暴岩的长期发育与长期稳定的强烈亚洲季风有关。
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| 关 键 词： | 丘状构造和洼状构造 HCS和SCS 湖泊风暴 鄂尔多斯盆地 |
| 收稿时间： | 2019-12-30 |
Discovery and Significance of Lake Storm Deposits in the Triassic-Jurassic of Eastern Dongsheng,Ordos Basin |
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| ZHONG JianHua,NI LiangTian,SUN NingLiang,HAO Bing,XUE ChunQi.Discovery and Significance of Lake Storm Deposits in the Triassic-Jurassic of Eastern Dongsheng,Ordos Basin[J].Acta Sedimentologica Sinica,2021,39(2):353-373. |
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| Authors: | ZHONG JianHua NI LiangTian SUN NingLiang HAO Bing XUE ChunQi |
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| Institution: | 1.State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology(Beijing), Beijing 100083, China2.Postdoctoral Scientific Research Station, Shengli Oilfield Company Ltd. , SINOPEC, Dongying, Shandong 257000, China3.School of Geosciences, China University of Petroleum (East China), Qingdao, Shandong 266580, China |
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| Abstract: | Mesozoic rocks are exposed in the northeastern corner of Ordos City.The main strata consist of a set of Triassic-Jurassic lacustrine deposits.Well-developed storm deposits and tempestites are found in the Triassic-Jurassic.The main site of the study is in the Triassic-Jurassic on both sides of National Highway 109 from Nalinhe coal mine to western Desheng,a distance of about 40 km.The western Desheng profile shows well-developed storm deposits and tempestites over a continuous length of 548 m.These are mainly a fluvial-delta-lacustrine deposit(with a few peat bogs),which is remarkable for its type-perfect HCS and SCS.Preliminary studies suggest that this set of storm deposits and storm rocks mainly developed in shallow lakes.The main features are as follows.(1)Where there are storm deposits or storm rocks,the stratification is very poor,and the strata are mostly lenticular,or lenticular/wavy.(2)The mounds and depressions form perfect medium-and large-scale continuous sinusoidal curves of wavelength ranging from several meters to nearly 100 meters,and amplitude ranging from tens of centimeters to 1-2 meters.(3)The lithology and its combinations are mainly a set of yellow-brown conglomerate+sandstone+gray mudstone.It has an obvious binary structure(lower coarse/upper fine).Stratification has developed in the upper part of the lower block.Conglomerate dominated by coarse debris is a common bottom deposit in the storm deposits.Storm deposits and tempestites have been formed by coal seams near the Nalinhe coal mine.(4)Gray gravel-bearing block mudstone with floating gravel reveals that it was deposited rapidly,similar to debris flows formed by storms rather than hydrostatic deposits formed in normal weather.The pebbly mudstone is tens of centimeters thick,which indicates a considerable rate of deposition at the time.(5)In western Desheng,a prominent profile of storm sediments and rock,the bottom developing the 1 to 3 thick gravel layers,with a middle layer tens of centimeters to 1-2 m thick and large amounts gravel 30-40 cm in diameter,most with imbricate structure.The former may be instructed the backflow storm in the direction of the lake,which indicates flushing flow to the lake shore caused by very strong storms.(6)Oscillatory flow is dominant,but has clear characteristics of composite and oscillatory flow in some places.(7)The overall sedimentary background is that of a broad,shallow lake environment,with mainly in situ oscillatory vertical deposition.Lake storm deposits and tempestites in the Triassic-Jurassic in Ordos is not usual;to date,no such large HCS and SCS have been reported anywhere worldwide.This study has shown that the lacustrine water in which these storm deposits and tempestites were formed was about 50 meters deep. |
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| Keywords: | hummocky structure and swaley structure HCS and SCS lacustrine storm Ordos Basin |
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