Meso-Cenozoic negative inversion model for the Linhe Depression of Hetao Basin, China

2021 ◽  
pp. 1-26
Author(s):  
Fusheng Yu ◽  
Ruifeng Zhang ◽  
Jiafu Yu ◽  
Yidan Wang ◽  
Shuguang Chen ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Morphological Changes ◽  
Kinematic Model ◽  
Seismic Interpretation ◽  
Thrust Belt ◽  
Key Factors ◽  
Analogue Modelling ◽  
Geological Conditions ◽  
Oil Flow ◽  
Dip Angle

Abstract The Linhe Depression is the largest tectonic unit in the Hetao Basin. The recently discovered commercial oil flow in the structural trap of wells JH2X and S5 has proved that the Meso-Cenozoic strata in the Linhe Depression have great exploration potential. Research on the kinematic model for the Mesozoic–Cenozoic Linhe Depression is important for analysing the geological conditions of hydrocarbon accumulation. In this study, field observations, seismic interpretation and scaled analogue modelling are performed. The results prove that the Linhe Depression experienced different stages of tectonic evolution, such as compressional depression (K1l), conversion from contraction to uniform subsidence (K1g), extensional rifting (E2–N2) and strike-slip deformation (Q), during the Mesozoic–Cenozoic eras. The kinematic model of negative inverted basins was first established with the early differential compression superimposed by the late extension. The seismic interpretation and analogue modelling results show that Jilantai Sag in the southern part of the Linhe Depression was subjected to compression from the Bayanwulashan fold–thrust belt on the NW side and the Helanshan fold–thrust belt on the SE side during Early Cretaceous time. Meanwhile, the Hanghou Sag in the northern part of the Linhe Depression was only compressed by the Langshan fold–thrust belt from the NW direction. The rifted structure generated by the extension from the SE direction during the Cenozoic Era resulted in the negative inversion of the pre-existing thrusts in different patterns. The intensity of negative inversion is controlled by several key factors, such as dip angle and the patterns of thrust faults, along with different basement textures. The morphological changes in the forebulge zone developed during Early Cretaceous time are responsible for the development of the segmented Central fault zones in the Hanghou Sag.

scholarly journals Key Factors Affecting the Deformation and Failure of Surrounding Rock Masses in Large-Scale Underground Powerhouses

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Meng Wang ◽  
Jia-wen Zhou ◽  
An-chi Shi ◽  
Jin-qi Han ◽  
Hai-bo Li
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Surrounding Rock ◽  
Rock Masses ◽  
Affecting Factors ◽  
Key Factors ◽  
Underground Powerhouse ◽  
Deformation And Failure ◽  
Factors Affecting ◽  
Geological Conditions

The stability of the surrounding rock masses of underground powerhouses is always emphasized during the construction period. With the general trends toward large-scale, complex geological conditions and the rapid construction progress of underground powerhouses, deformation and failure issues of the surrounding rock mass can emerge, putting the safety of construction and operation in jeopardy and causing enormous economic loss. To solve these problems, an understanding of the origins and key affecting factors is required. Based on domestic large-scale underground powerhouse cases in the past two decades, key factors affecting the deformation and failure of the surrounding rock mass are summarized in this paper. Among these factors, the two most fundamental factors are the rock mass properties and in situ stress, which impart tremendous impacts on surrounding rock mass stability in a number of cases. Excavation is a prerequisite of surrounding rock mass failure and support that is classified as part of the construction process and plays a pivotal role in preventing and arresting deformation and failure. Additionally, the layout and structure of the powerhouse are consequential. The interrelation and interaction of these factors are discussed at the end of this paper. The results can hopefully advance the understanding of the deformation and failure of surrounding rock masses and provide a reference for design and construction with respect to hydroelectric underground powerhouses.

scholarly journals Examining the tectono-stratigraphic architecture, structural geometry, and kinematic evolution of the Himalayan fold-thrust belt, Kumaun, northwest India

Lithosphere ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 414-435 ◽  
Author(s):  
Subhadip Mandal ◽  
Delores M. Robinson ◽  
Matthew J. Kohn ◽  
Subodha Khanal ◽  
Oindrila Das
Keyword(s):  
Cross Section ◽  
Structural Model ◽  
Kinematic Model ◽  
Thrust Belt ◽  
Main Central Thrust ◽  
Thrust Sheet ◽  
Balanced Cross Section ◽  
Kinematic Evolution ◽  
Thrust Sheets ◽  
Northwest India

Abstract Existing structural models of the Himalayan fold-thrust belt in Kumaun, northwest India, are based on a tectono-stratigraphy that assigns different stratigraphy to the Ramgarh, Berinag, Askot, and Munsiari thrusts and treats the thrusts as separate structures. We reassess the tectono-stratigraphy of Kumaun, based on new and existing U-Pb zircon ages and whole-rock Nd isotopic values, and present a new structural model and deformation history through kinematic analysis using a balanced cross section. This study reveals that the rocks that currently crop out as the Ramgarh, Berinag, Askot, and Munsiari thrust sheets were part of the same, once laterally continuous stratigraphic unit, consisting of Lesser Himalayan Paleoproterozoic granitoids (ca. 1850 Ma) and metasedimentary rocks. These Paleoproterozoic rocks were shortened and duplexed into the Ramgarh-Munsiari thrust sheet and other Paleoproterozoic thrust sheets during Himalayan orogenesis. Our structural model contains a hinterland-dipping duplex that accommodates ∼541–575 km or 79%–80% of minimum shortening between the Main Frontal thrust and South Tibetan Detachment system. By adding in minimum shortening from the Tethyan Himalaya, we estimate a total minimum shortening of ∼674–751 km in the Himalayan fold-thrust belt. The Ramgarh-Munsiari thrust sheet and the Lesser Himalayan duplex are breached by erosion, separating the Paleoproterozoic Lesser Himalayan rocks of the Ramgarh-Munsiari thrust into the isolated, synclinal Almora, Askot, and Chiplakot klippen, where folding of the Ramgarh-Munsiari thrust sheet by the Lesser Himalayan duplex controls preservation of these klippen. The Ramgarh-Munsiari thrust carries the Paleoproterozoic Lesser Himalayan rocks ∼120 km southward from the footwall of the Main Central thrust and exposed them in the hanging wall of the Main Boundary thrust. Our kinematic model demonstrates that propagation of the thrust belt occurred from north to south with minor out-of-sequence thrusting and is consistent with a critical taper model for growth of the Himalayan thrust belt, following emplacement of midcrustal Greater Himalayan rocks. Our revised stratigraphy-based balanced cross section contains ∼120–200 km greater shortening than previously estimated through the Greater, Lesser, and Subhimalayan rocks.

Seismic interpretation of fault-related deformation using a numerical kinematic model

2016 ◽  
Author(s):  
Gabriel Godefroy ◽  
Guillaume Caumon ◽  
Gautier Laurent ◽  
Mary Ford
Keyword(s):  
Kinematic Model ◽  
Seismic Interpretation

Improving 2D seismic interpretation in challenging settings by integration of restoration techniques: A case study from the Jura fold-and-thrust belt (Switzerland)

2015 ◽  
Vol 3 (4) ◽  
pp. SAA37-SAA58 ◽  
Author(s):  
Alexander Malz ◽  
Herfried Madritsch ◽  
Jonas Kley
Keyword(s):  
Cross Section ◽  
Lower Triassic ◽  
Seismic Profile ◽  
Seismic Interpretation ◽  
Mountain Range ◽  
Thrust Belt ◽  
Jura Mountains ◽  
Northern Switzerland ◽  
Fold And Thrust Belt

The structural geologic interpretation of reflection seismic data is affected by conceptual uncertainty, particularly in challenging onshore settings. This uncertainty can be significantly reduced by the integration of cross-section restoration and balancing techniques into the seismic interpretation workflow. Moreover, these techniques define a solid and comprehensive basis, grounding the interpretation and allowing a closer investigation of the deformation history that led to the interpreted structures. These benefits are demonstrated on the basis of a case study from the eastern Jura Mountains in northern Switzerland. This mountain range was formed by a thin-skinned foreland fold-and-thrust belt with a multiphase prethrusting tectonic history. Despite significant seismic acquisition and processing efforts, seismic imaging of the strongly deformed parts of the belt widely remains ambiguous. We have developed a detailed systematic interpretation workflow that is exemplified here for a single seismic profile across the Jura Main Thrust. Classical cross-section balancing techniques of equal bed lengths and areas were applied to validate and reinterpret the given seismic interpretation. Our results suggest that most of the observed structures resulted from thin-skinned deformation along a basal décollement in Lower Triassic evaporites, which is generally inferred for the Jura Mountains. Nevertheless, secondary detachment levels in above lying strata have to be considered as well. The stepwise restoration of the analyzed cross section points toward different styles of thin-skinned deformation and possibly several episodes of earlier basement-rooted faulting events, which are indicated by subtle stratigraphic thickness changes. In summary, our workflow allowed us to significantly improve the original seismic interpretation, highlight specific deformation styles, and illuminate possible prethrusting deformation events that would otherwise be easily overlooked.

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