The Laramie River after flowing in a north direction through southeast Wyoming’s Laramie Basin abruptly turns in an east direction to flow across the north-to-south oriented Laramie Range in a bedrock-walled canyon a...The Laramie River after flowing in a north direction through southeast Wyoming’s Laramie Basin abruptly turns in an east direction to flow across the north-to-south oriented Laramie Range in a bedrock-walled canyon and eventually reaches the lower elevation Great Plains and southeast-oriented North Platte River. The North Laramie River, Bluegrass Creek, and North Sybille/Sybille Creek also flow from the Laramie Basin in separate bedrock-walled valleys into the Laramie Range before eventually joining the Laramie River. Bedrock-walled through valleys link the various Laramie Range stream and river crossing valleys and detailed topographic maps were used to determine how this anastomosing bedrock-walled canyon complex and the large escarpment-surrounded Goshen Hole basin (located just to the east of the anastomosing canyon complex) originated. Map evidence shows multiple streams of water must have diverged in the Laramie Basin from the north-oriented Laramie River to enter the Laramie Range before converging in or east of the Laramie Range and also shows how present day through valleys enabled diverging and converging streams of water to cross the Laramie Range. The anastomosing bedrock-walled valley complex studied here extends from north of the North Laramie River valley to south of the North Sybille/Sybille Creek valley. Large volumes of water flowing from the Laramie Basin to the Great Plains are interpreted to have eroded the anastomosing canyon complex and the “downstream” Goshen Hole escarpment-surrounded basin. Headward erosion of the north-oriented Sybille and Chugwater Creek valleys across large sheets of east-oriented water are interpreted to have left the Goshen Hole escarpment-surrounded basin as a large abandoned headcut. A water source was not determined, although a continental ice sheet that deeply eroded and warped the North American continent is considered to be a possible source.展开更多
Based on the Late Paleozoic geological background and the latest exploration achievements of the Ordos Basin and North China platform, it is concluded that during the sedimentary period of Permian He 8 Member, the are...Based on the Late Paleozoic geological background and the latest exploration achievements of the Ordos Basin and North China platform, it is concluded that during the sedimentary period of Permian He 8 Member, the area in concern had multiple material sources, multiple river systems, flat terrain, shallow sedimentary water, widely distributed fluvial facies sand body and no continuous lake area, so alluvial river sedimentary system developed in the whole region. Based on stratigraphic correlation and division, and a large number of drilling and outcrop data, a comprehensive analysis of lithofacies and sedimentary facies types and distribution was carried out to reconstruct the ancient geographic pattern of the He 8 Member sedimentary period. The results of paleogeography restoration show that the area of Ordos Basin was the "runoff area" in the sedimentary slope in the western part of the North China platform during the sedimentary period of He 8 Member, the whole region was mainly alluvial plain sedimentation featuring alternate fluvial facies, flood plain facies and flood-plain lake facies. According to the results of flume deposition simulation experiment, a new sedimentary model of "alluvial river & flood-plain lake" is established, which reveals the genesis of large area gravel sand body in He 8 Member of this area and provides geological basis for the exploration of tight gas in the south of the basin.展开更多
Wetland is a new type of sedimentary facies proposed for the first time in this paper. It is a type of sedimentary environment, transitional between land facies and water (sea or lake) facies. In this paper, wetland i...Wetland is a new type of sedimentary facies proposed for the first time in this paper. It is a type of sedimentary environment, transitional between land facies and water (sea or lake) facies. In this paper, wetland is redefined as “a type of sedimentary environments whose ground surface is flat and wet throughout the year, which may be covered with very shallow water (less than 2 m deep), and is covered with lush plant growth”. Wetland is reclassified into two types, swamp wetland (swamp in brief) and wet plain wetland (wet plain in brief). Swamp deposits are coal, while wet plain deposits are dark colored mudstones or silty mudstones rich in plant fossils and carbon debris. The deposits of wet plain are different from those of lake and floodplain in the abundance of plant fossils, color, resistivity well logging curve, and other sedimentary characteristics. In boreholes, resistivity logging can be used to distinguish between wet plain mudstones and lake mudstones. Understanding the sedimentary characteristics of wet plain wetland can help to identify wet plain deposits which were formerly classified as floodplain or lake deposits. This will help to reconstruct the palaeogeography and to understand the history of basin and climate evolution accurately, and is especially important in evaluation of the hydrocarbon generating potential of a basin. With the Jurassic Sangonghe Formation of the Yanqi Basin as an example, the identification characteristics of wetland are described.展开更多
Taking the Songnen Plain as the research region and basing on the structural division of river water resources, the impounding models of flood water utilization are proposed. Considering the water requirement, potenti...Taking the Songnen Plain as the research region and basing on the structural division of river water resources, the impounding models of flood water utilization are proposed. Considering the water requirement, potential impoundage and the degree of risk, two modes of the flood water utilization are developed: full impounding and partial impounding. A risk assessment method is put forward according to variation of the flood storage capacity before and after impounding water. A representative hydrological year is taken as an example to analyze the application of the model at the downstream of the Nenjiang River. It is found that the model is very useful for the flood utilization and protection. For flood utilization, the spring drought can be relieved and the risk of impounding water is also acceptable. For flood protection, the river flood peak can be largely reduced and the impounding water can increase the river discharge at the low water period, at the same time the structure of river water resources can be improved as well.展开更多
文摘The Laramie River after flowing in a north direction through southeast Wyoming’s Laramie Basin abruptly turns in an east direction to flow across the north-to-south oriented Laramie Range in a bedrock-walled canyon and eventually reaches the lower elevation Great Plains and southeast-oriented North Platte River. The North Laramie River, Bluegrass Creek, and North Sybille/Sybille Creek also flow from the Laramie Basin in separate bedrock-walled valleys into the Laramie Range before eventually joining the Laramie River. Bedrock-walled through valleys link the various Laramie Range stream and river crossing valleys and detailed topographic maps were used to determine how this anastomosing bedrock-walled canyon complex and the large escarpment-surrounded Goshen Hole basin (located just to the east of the anastomosing canyon complex) originated. Map evidence shows multiple streams of water must have diverged in the Laramie Basin from the north-oriented Laramie River to enter the Laramie Range before converging in or east of the Laramie Range and also shows how present day through valleys enabled diverging and converging streams of water to cross the Laramie Range. The anastomosing bedrock-walled valley complex studied here extends from north of the North Laramie River valley to south of the North Sybille/Sybille Creek valley. Large volumes of water flowing from the Laramie Basin to the Great Plains are interpreted to have eroded the anastomosing canyon complex and the “downstream” Goshen Hole escarpment-surrounded basin. Headward erosion of the north-oriented Sybille and Chugwater Creek valleys across large sheets of east-oriented water are interpreted to have left the Goshen Hole escarpment-surrounded basin as a large abandoned headcut. A water source was not determined, although a continental ice sheet that deeply eroded and warped the North American continent is considered to be a possible source.
基金Supported by the China National Science and Technology Major Project(2011ZX05044,2011ZX05007-004)
文摘Based on the Late Paleozoic geological background and the latest exploration achievements of the Ordos Basin and North China platform, it is concluded that during the sedimentary period of Permian He 8 Member, the area in concern had multiple material sources, multiple river systems, flat terrain, shallow sedimentary water, widely distributed fluvial facies sand body and no continuous lake area, so alluvial river sedimentary system developed in the whole region. Based on stratigraphic correlation and division, and a large number of drilling and outcrop data, a comprehensive analysis of lithofacies and sedimentary facies types and distribution was carried out to reconstruct the ancient geographic pattern of the He 8 Member sedimentary period. The results of paleogeography restoration show that the area of Ordos Basin was the "runoff area" in the sedimentary slope in the western part of the North China platform during the sedimentary period of He 8 Member, the whole region was mainly alluvial plain sedimentation featuring alternate fluvial facies, flood plain facies and flood-plain lake facies. According to the results of flume deposition simulation experiment, a new sedimentary model of "alluvial river & flood-plain lake" is established, which reveals the genesis of large area gravel sand body in He 8 Member of this area and provides geological basis for the exploration of tight gas in the south of the basin.
基金supported by the "973" National Major Fundamental Research & Development Project "Reservoir-forming mechanism and distribution law of oil and gas in superimposed basins of China" (2006C13202300)
文摘Wetland is a new type of sedimentary facies proposed for the first time in this paper. It is a type of sedimentary environment, transitional between land facies and water (sea or lake) facies. In this paper, wetland is redefined as “a type of sedimentary environments whose ground surface is flat and wet throughout the year, which may be covered with very shallow water (less than 2 m deep), and is covered with lush plant growth”. Wetland is reclassified into two types, swamp wetland (swamp in brief) and wet plain wetland (wet plain in brief). Swamp deposits are coal, while wet plain deposits are dark colored mudstones or silty mudstones rich in plant fossils and carbon debris. The deposits of wet plain are different from those of lake and floodplain in the abundance of plant fossils, color, resistivity well logging curve, and other sedimentary characteristics. In boreholes, resistivity logging can be used to distinguish between wet plain mudstones and lake mudstones. Understanding the sedimentary characteristics of wet plain wetland can help to identify wet plain deposits which were formerly classified as floodplain or lake deposits. This will help to reconstruct the palaeogeography and to understand the history of basin and climate evolution accurately, and is especially important in evaluation of the hydrocarbon generating potential of a basin. With the Jurassic Sangonghe Formation of the Yanqi Basin as an example, the identification characteristics of wetland are described.
基金the National Natural Science Foundation of China (Grant Nos. 50139020 and 50679012)
文摘Taking the Songnen Plain as the research region and basing on the structural division of river water resources, the impounding models of flood water utilization are proposed. Considering the water requirement, potential impoundage and the degree of risk, two modes of the flood water utilization are developed: full impounding and partial impounding. A risk assessment method is put forward according to variation of the flood storage capacity before and after impounding water. A representative hydrological year is taken as an example to analyze the application of the model at the downstream of the Nenjiang River. It is found that the model is very useful for the flood utilization and protection. For flood utilization, the spring drought can be relieved and the risk of impounding water is also acceptable. For flood protection, the river flood peak can be largely reduced and the impounding water can increase the river discharge at the low water period, at the same time the structure of river water resources can be improved as well.
