Cenozoic growth of West Kunlun Mountains and tectono-sedimentary evolution of adjacent SW Tarim Basin-New spatial model based on seismic data

Author(s):  
Wenhang Liu ◽  
Piotr Krzywiec ◽  
Stanisław Mazur ◽  
Fanwei Meng ◽  
Qingong Zhuo ◽  
...  

<p>Kunlun Mountains, SW part of the Tarim Basin and S edge of the Bachu Uplift in central Asia collectively form the northernmost segment of the vast Cenozoic deformation zone and associated depositional areas formed in course of the India – Euroasia collision. Five seismic transects from the SW Tarim Basin (Yechang - Hotan area) calibrated by deep wells were used in order to assess lateral variations of a structural style and syn-tectonic sedimentation in this part of the basin. Pre-Cenozoic substratum of SW Tarim Basin is formed by crystalline basement covered by Paleozoic strata, with important mid-Cambrian evaporites (Awatage Formation) that served as first, deep detachment level. Cenozoic sedimentary infill consists of several kilometers of shallow water to terrestrial clastics with Paleogene evaporites of the Bashiblake Formation at their base. Paleogene evaporites acted as a second, shallow detachment. Mid – late Miocene to Quaternary wedging along the front of the Kunlun Mts., associated with formation of a large-scale duplex consisting of slivers built of Precambrian to Permian rocks, resulted in progressive, laterally variable uplift of the S margin of the Tarim Basin documented by well-preserved growth strata that have been also described in the field. Jade Anticline, large intra-basinal structure that is located in the central part of the Tarim Basin, previously interpreted as a regional wrenching zone, was reinterpreted as a thin-skinned syn-depositional “fish tail” structure, detached in the Paleogene evaporites and formed in Quaternary above local basement elevation. Northernmost late Miocene compressional deformations have been recognized along the S edge of the Bachu Uplift in its Western and central segment. They formed due to complex interplay of thick-skinned basement reverse faulting responsible for regional elevation of basement blocks, and two types of thin-skinned thrusting: southward directed thrusting detached within the mid-Cambrian evaporites and northward directed thrusting detached within the Paleogene evaporites. Compressional deformations along the S edge of the Bachu Uplift are diminishing and eventually disappearing towards the East. All these findings point to significant transfer of compressional stresses into the far foreland of the W Kunlun Mountains and laterally variable tectonic coupling between the Tibet Plateau and central part of the Tarim Basin.</p><p>Seismic data used in this study was kindly provided by China National Petroleum Corporation (PetroChina). IHS Markit is thanked for providing academic license of Kingdom seismic interpretation software.</p>

2021 ◽  
Author(s):  
Wenhang Liu ◽  
Piotr krzywiec ◽  
Stanisław Mazur ◽  
Fanwen Meng ◽  
Zhuxin Chen

<p>The vast Tarim basin is surrounded by Tian Shan Mountains in the north, West Kunlun Mountains in the southwest, and the Altyn Mountains in the southeast. The southwestern Tarim Basin developed within the foreland of the West Kunlun Mountains and cumulated up to 10 km of Cenozoic strata. Despite several decades of geological studies its structural styles and details of its geological evolution are still being debated. In this study, we used seven regional seismic transects from the Yecheng - Hotan area calibrated by deep wells to assess lateral variations of a structural style and syn-tectonic sedimentation in this part of the basin.</p><p>The basement of the SW Tarim Basin is covered by Paleozoic and Cenozoic strata, as revealed by several deep calibration wells. The regional north-directed basement thrust together with two evaporitic detachments including the Middle Cambrian evaporites (Awatage Formation) and Paleogene evaporites (Aertashi Formation) controlled the overall tectonic framework and structural evolution of this part of the basin. The visible growth strata on seismic data indicate progressive development of the structural wedge within the frontal W Kunlun Mountains from the Late Miocene to the Present day.</p><p>Four main Cenozoic evolutionary stages of the W Kunlun Mountains and adjacent SW Tarim Basin have been determined. At the end of Paleogene, evaporites of the Aertashi Formation have been deposited in SW Tarim Basin; their thickness, as indicated by seismic data, increases towards the Kunlun orogenic wedge which suggests their deposition within the flexural foreland basin. Then, during the Early to Middle Miocene, about 4000m of sediments have been deposited in rapidly subsiding foreland basin. Towards the end of Late Miocene-Pliocene, tectonic wedging along thrust front led to significant uplift of the Kunlun Mountains that presently form S margin of the Tarim Basin. Quaternary migration of compressional deformations towards the North, towards the basin interior led to formation of the intra-basinal Jade anticline that was re-interpreted as a thin-skinned syn-depositional “fish tail” structure detached within the Paleogene evaporites. Present-day activity along some deeply buried thrusts of the Kunlun Mts. tectonic wedge might be related to current earthquakes.</p>


2021 ◽  
Author(s):  
Wajdi Belkhiria ◽  
Haifa Boussiga ◽  
Imen Hamdi Nasr ◽  
Adnen Amiri ◽  
Mohamed Hédi Inoubli

<p>The Sahel basin in eastern Tunisia has been subject for hydrocarbon exploration since the early fifties. Despite the presence of a working petroleum system in the area, most of the drilled wells were dry or encountered oil shows that failed to give commercial flow rates. A better understanding of the tectono-sedimentary evolution of the Sahel basin is of great importance for future hydrocarbon prospectivity. In this contribution, we present integration of 2D seismic reflection profiles, exploration wells and new acquired gravity data. These subsurface data reveal that the Sahel basin developed as a passive margin during Jurassic-Early Cretaceous times and was later inverted during the Cenozoic Alpine orogeny. The occurrence of Triassic age evaporites and shales deposited during the Pangea breakup played a fundamental role in the structural style and tectono-sedimentary evolution of the study area. Seismic and gravity data revealed jointly important deep-seated extensional faults, almost along E-W and few along NNE–SSW and NW-SE directions, delimiting horsts and grabens structures. These syn-rift extensional faults controlled deposition, facies distribution and thicknesses of the Jurassic and Early cretaceous series. Most of these inherited deep-seated normal and transform faults are ornamented by different types of salt-related structures. The first phase of salt rising was initiated mainly along these syn-extensional faults in the Late Jurassic forming salt domes and continued into the Early and Late Cretaceous leading to salt-related diapir structures. During this period, the salt diapirism was accompanied by the development of salt withdrawal minibasins, characterized important growth strata due the differential subsidence. These areas represent important immediate kitchen areas to the salt-related structures. The later Late Cretaceous - Cenozoic shortening phases induced preferential rejuvenation of the diapiric structures and led to the inversion of former graben/half-graben structures and ultimately to vertical salt welds along salt ridges. These salt structures represent key elements that remains largely undrilled in the Sahel basin. Our results improve the understanding of salt growth in eastern Tunisia and consequently greatly impact the hydrocarbon prospectivity in the area.</p>


2021 ◽  
Author(s):  
Adam J. Cawood ◽  
David A. Ferrill ◽  
Alan P. Morris ◽  
David Norris ◽  
David McCallum ◽  
...  

<p>The Orphan Basin on the eastern edge of the Newfoundland continental margin formed as a Mesozoic rift basin prior to continental breakup associated with the opening of the North Atlantic. Few exploration wells exist in the basin, and until recently regional interpretations have been based on sparse seismic data coverage - because of this the structural evolution of the Orphan Basin has historically not been well understood. Key uncertainties include the timing and amount of rift-related extension, dominant extension directions, and the structural styles that accommodated progressive rift development in the basin.     </p><p>Interpretation of newly acquired modern broadband seismic data and structural restoration of three regional, WNW-ESE oriented cross-sections across the Orphan Basin and Flemish Cap provide new insights into rift evolution and structural style in the area. Our results show that major extension in the basin occurred between 167 Ma and 135 Ma, with most extension occurring prior to 151 Ma. We show that extension after 135 Ma largely occurred east of Flemish Cap due to a shift in the locus of rifting from the Orphan Basin to east of Flemish Cap. We find no evidence for discrete rifting events in the Orphan Basin, as has been suggested by other authors.  Kinematic restoration and associated heave measurements for the Orphan Basin show that extension was both widespread and relatively evenly distributed across the basin from Middle-Late Jurassic to Early Cretaceous.</p><p>We provide evidence for more widespread deposition of Jurassic strata throughout the Orphan Basin than previously interpreted, and show that Jurassic deposition was controlled by the occurrence and displacement of crustal-scale extensional detachment faults.  Structure in the three regional cross sections is dominated by large-scale, shallowly dipping extensional detachment faults. These faults mainly dip to the northwest and control the geometry and position of extensional basins – grabens and half-grabens – which occur at a range of scales. Stacked detachment surfaces, hyperextension, and attenuation of the crust are observed in central and eastern parts of the Orphan Basin. Zones of extreme crustal attenuation (to ca. 3.7 km) are interpreted to be coincident with large-displacement (up to 60 km) low-angle detachments. Results from crustal area balancing suggest that up to 41% of extension is not recognized through structural seismic interpretation, which we attribute to subseismic-scale ductile and brittle deformation, and uncertainties in the identification of detachment surfaces or complex structural configurations (e.g., overprinting of early extensional deformation).</p><p>Rifting style in the central, northern, and eastern parts of the Orphan Basin is dominated by low-angle detachment faulting with maximum extension perpendicular to the incipient rift axis. In contrast, structural geometries in the southwestern part of the basin are suggestive of transtensional deformation, and interplay of normal and strike-slip faulting.  Results from map-based interpretation show that strike-slip faults within this transtensional zone are associated with displacement transfer between half-grabens of opposing polarity, rather than regional strike-slip displacement.  These structures are interpreted as contemporaneous and kinematically linked to displacement along low-angle detachment surfaces elsewhere, and are not attributed to distinct episodes of oblique extension.       </p>


Author(s):  
Nguyen Thi Phuong Thao ◽  
Tran Nghi ◽  
Dinh Xuan Thanh

The characteristics of late Miocene lithofacies in the southeast region of  Hanoi depression have been revealed on the basis of sedimentary evolution in relation to sea level change and tectonic movement. During late Miocene, global sea level change has created one depositional sequence and three sedimentary systems tract. The lowstand systems tract (LST) is characterized by 5 rhythms of  alluvial lithofacies. These rhythms are represented by rough, humoc seismic wave  fields. This environment is not favorable condition for coal formation. The transgressive systems tract (TST) is characterized by 6 transitional lithofacies rhythms. Each lithofacies rhythm consists of 4 facies: the tidal flats sand facies of the bay, the  mud facies of the river mouth lagoon, the coastal marshy mud facies creating coal and the bay greenish-gray clay facies. The pacing process involves changes in the local sea level caused by tectonic lift. Each tectonic subsidence phase takes place at a very slow velocity, so it is compensated for fine-grained sediment creating marshy mud facies to develop mangroves on a large scale. It is a prerequisite to create thick coal seams distributed near the end of each rhythm. A part of highstand systems tract (HST) are eroded due to the improved folding process, creating an angular unconformity boundary with Pliocene-Quaternary sediments. However, after reconstracting of deformated section, it was clear that this systems tract  had only one  rhythm including 2 facies: prodelta mud facies and alluvial fan sandstone facies. Keywords: Lithofacies-paleogeography, sedimentary systems tract, sedimentary rhythm


2021 ◽  
Vol 13 (6) ◽  
pp. 1180
Author(s):  
Da Guo ◽  
Xiaoning Song ◽  
Ronghai Hu ◽  
Xinming Zhu ◽  
Yazhen Jiang ◽  
...  

The Hindu Kush Himalayan (HKH) region is one of the most ecologically vulnerable regions in the world. Several studies have been conducted on the dynamic changes of grassland in the HKH region, but few have considered grassland net ecosystem productivity (NEP). In this study, we quantitatively analyzed the temporal and spatial changes of NEP magnitude and the influence of climate factors on the HKH region from 2001 to 2018. The NEP magnitude was obtained by calculating the difference between the net primary production (NPP) estimated by the Carnegie–Ames Stanford Approach (CASA) model and the heterotrophic respiration (Rh) estimated by the geostatistical model. The results showed that the grassland ecosystem in the HKH region exhibited weak net carbon uptake with NEP values of 42.03 gC∙m−2∙yr−1, and the total net carbon sequestration was 0.077 Pg C. The distribution of NEP gradually increased from west to east, and in the Qinghai–Tibet Plateau, it gradually increased from northwest to southeast. The grassland carbon sources and sinks differed at different altitudes. The grassland was a carbon sink at 3000–5000 m, while grasslands below 3000 m and above 5000 m were carbon sources. Grassland NEP exhibited the strongest correlation with precipitation, and it had a lagging effect on precipitation. The correlation between NEP and the precipitation of the previous year was stronger than that of the current year. NEP was negatively correlated with temperature but not with solar radiation. The study of the temporal and spatial dynamics of NEP in the HKH region can provide a theoretical basis to help herders balance grazing and forage.


Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 293
Author(s):  
Wei Tian ◽  
Xiaomin Li ◽  
Lei Wang

Disparities between fold amplitude (A) and intrusion thickness (Hsill) are critical in identifying elastic or inelastic deformation in a forced fold. However, accurate measurements of these two parameters are challenging because of the limit in separability and detectability of the seismic data. We combined wireline data and 3-D seismic data from the TZ-47 exploring area in the Tarim Basin, Northwest China, to accurately constrain the fold amplitude and total thickness of sills that induced roof uplift in the terrain. Results from the measurement show that the forced fold amplitude is 155.0 m. After decompaction, the original forced fold amplitude in the area penetrated by the well T47 ranged from 159.9 to 225.8 m, which overlaps the total thickness of the stack of sills recovered by seismic method (171.4 m) and well log method (181.0 m). Therefore, the fold amplitude at T47 area is likely to be elastic. In contrast, the outer area of the TZ-47 forced fold is characterized by shear-style deformation, indicating inelastic deformation at the marginal area. It is suggested that interbedded limestone layers would play an important role in strengthening the roof layers, preventing inelastic deformation during the emplacement of intrusive magma.


2019 ◽  
Vol 500 (1) ◽  
pp. 531-549 ◽  
Author(s):  
Suzanne Bull ◽  
Joseph A. Cartwright

AbstractThis study shows how simple structural restoration of a discrete submarine landslide lobe can be applied to large-scale, multi-phase examples to identify different phases of slide-lobe development and evaluate their mode of emplacement. We present the most detailed analysis performed to date on a zone of intense contractional deformation, historically referred to as the compression zone, from the giant, multi-phase Storegga Slide, offshore Norway. 2D and 3D seismic data and bathymetry data show that the zone of large-scale (>650 m thick) contractional deformation can be genetically linked updip with a zone of intense depletion across a distance of 135 km. Quantification of depletion and accumulation along a representative dip-section reveals that significant depletion in the proximal region is not accommodated in the relatively mild amount (c. 5%) of downdip shortening. Dip-section restoration indicates a later, separate stage of deformation may have involved removal of a significant volume of material as part of the final stages of the Storegga Slide, as opposed to the minor volumes reported in previous studies.


Sign in / Sign up

Export Citation Format

Share Document