Construction of the Lesser Himalayan–Subhimalayan thrust belt: The primary driver of thickening, exhumation, and high elevations in the Himalayan orogen since the middle Miocene

Geology ◽  
2021 ◽  
Author(s):  
Sean P. Long ◽  
Delores M. Robinson
Keyword(s):  
Cross Sections ◽  
Middle Miocene ◽  
Structural Evolution ◽  
Crustal Thickening ◽  
Thrust Belt ◽  
Himalayan Orogen ◽  
Orogenic Wedge ◽  
Primary Driver ◽  
Thrust Sheets ◽  
High Elevations

Documenting the structural evolution of the Himalayan orogen is fundamental for understanding the dynamics of collisional orogenesis. We argue that the importance of deformation in the frontal, Lesser Himalayan–Subhimalayan (LH-SH) portion of the Himalayan thrust belt for driving crustal thickening over the past ~15–13 m.y. has long been overlooked. To quantify its contribution to thickening, we measured parameters from 22 published cross sections that span the length of the orogen. The mean structural uplift accomplished by the LH-SH thrust belt increases from 10–15 km in the eastern half of the orogen to 15–23 km in the western half. An antiformal culmination constructed by LH duplexing is observed across the orogen and increases in structural height (to as much as 15–20 km) and north-south width moving westward. Construction of the culmination was the primary mechanism for building and maintaining wedge taper. The westward scaling of culmination size is accompanied by doubling and tripling of LH-SH shortening and accretion magnitude, respectively; when combined with a consistent orogen-wide modern taper angle (11° ± 2°), this indicates that duplexing facilitated the growth of an overall larger orogenic wedge moving westward. Following the initial southward propagation of deformation into LH rocks at ca. 15–13 Ma, the Himalayan orogenic wedge has been characterized by stacking of multiple thin, smalldisplacement thrust sheets to develop a high-taper orogenic wedge. Thus, LH-SH deformation has had a profound effect on driving thickening, exhumation, and the attainment of high elevations since the middle Miocene.

scholarly journals Supplemental Material: Construction of the Lesser Himalayan–Subhimalayan thrust belt: The primary driver of thickening, exhumation, and high elevations in the Himalayan orogen since the middle Miocene

2021 ◽  
Author(s):  
Sean P. Long ◽  
Delores M. Robinson
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Middle Miocene ◽  
Thrust Belt ◽  
Himalayan Orogen ◽  
Primary Driver ◽  
High Elevations

Supplemental figures and tables that provide supporting data for the compiled cross sections and the measured parameters, as well as text that summarizes the tectonostratigraphic units on each cross section.<br>

scholarly journals Supplemental Material: Construction of the Lesser Himalayan–Subhimalayan thrust belt: The primary driver of thickening, exhumation, and high elevations in the Himalayan orogen since the middle Miocene

2021 ◽  
Author(s):  
Sean P. Long ◽  
Delores M. Robinson
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Middle Miocene ◽  
Thrust Belt ◽  
Himalayan Orogen ◽  
Primary Driver ◽  
High Elevations

Supplemental figures and tables that provide supporting data for the compiled cross sections and the measured parameters, as well as text that summarizes the tectonostratigraphic units on each cross section.<br>

Structure of the Gare Kakheti foothills using seismic reflection profiles: implications for kinematic evolution of the Georgian part of Kura foreland fold-and-thrust belt

2020 ◽  
Author(s):  
Alexander Razmadze
Keyword(s):  
Cross Sections ◽  
Seismic Reflection ◽  
Structural Evolution ◽  
Foreland Basin ◽  
Thrust Belt ◽  
Fault Propagation ◽  
Seismic Reflection Data ◽  
Growth Strata ◽  
Kinematic Evolution ◽  
Fold And Thrust Belt

&lt;p&gt;Gare Kakheti foothills are located between Lesser Caucasus and Kakheti Ridge and are mainly represented by the series of NEN dipping thrust faults, most of which are associated with fault&amp;#8208;related folds. Gare Kakheti foothills as a part of the Kura foreland fold-and-thrust belt developed formerly as a foreland basin (Oligocene-Lower Miocene) (e.g. Alania et al., 2017). Neogene shallow marine and continental sediments in the Gare Kakheti foothills keep the record on the stratigraphy and structural evolution of the study area during the compressive deformation. Interpreted seismic profiles and structural cross-sections across the Udabno, Tsitsmatiani, and Berebisseri synclines show that they are thrust-top basins. Seismic reflection data reveal the presence of growth fault-propagation folds and some structural wedges (or duplex). The evolution of the Udabno, Tsitsmatiani, and Berebisseri basins is compared with simple models of thrust-top basins whose development is controlled by the kinematics of competing for growth anticlines. Growth anticlines are mainly represented by fault-propagation folds. The geometry of growth strata in associated footwall synclines and the sedimentary infill of thrust-top basins provide information on the thrusting activity in terms of location, geometry, and age.&lt;br&gt;This work was supported by Shota Rustaveli National Science Foundation (SRNSF - #PHDF-19-268).&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Structure, strain and AMS of the Uzunakhmat thrust sheet (Talas Range, Kyrgyz North Tian Shan)

2020 ◽  
Author(s):  
Anastasia Kushnareva ◽  
Artem Moskalenko ◽  
Alexander Pasenko
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Structural Evolution ◽  
Middle Part ◽  
Tien Shan ◽  
Initial Shape ◽  
Thrust Sheet ◽  
Structural Style ◽  
Thrust Sheets ◽  
Tian Shan

&lt;p&gt;The Talas Range forms the northwest part of the Caledonides of the Northern Tian Shan. Based on differences in the structural style, metamorphism and sedimentary successions, three thrust sheets have been identified &amp;#8211; the Uzunakhmat, Talas, and Kumyshtag thrust sheets. The Talas and Kumyshtag thrust sheets consist of Neoproterozoic-Ordovician terrigenous and carbonate rock units, whereas the Uzunakhmat thrust sheet consists of Neoproterozoic terrigenous rocks metamorphosed up to greenschist facies. The Uzunakhmat thrust sheet is separated from the Talas and Kumyshtag thrust sheets by the southwest-dipping Central Talas thrust (CTT). The dextral strike-slip Talas-Fergana Fault bounds the Uzunakhmat thrust sheet in the southwest. The main deformation events occurred in the Middle-Late Ordovician.&lt;/p&gt;&lt;p&gt;Structural and strain studies were done along profiles normal to the strike of folds and faults and located in the northwest and southeast parts of the Uzunakhmat thrust sheet. We also incorporate in our study structural profile in the central part of the Uzunakhmat thrust sheet, documented by Khudoley (1993) and Voytenko &amp; Khudoley (2012).&lt;/p&gt;&lt;p&gt;The main strain indicators were detrital quartz grains in sandstones. Rf/&amp;#966; and Normalized Fry methods were used to identify the amount of strain. Oblate ellipsoids predominate with Rxz values varying mostly from 1,6 to 2,4. Long axes of strain ellipsoids are sub-horizontal with the southeast to east-southeast trend. Similar trends have long axes of the anisotropy magnetic susceptibility ellipsoid being parallel to fold axes, cleavage-bedding intersection and mineral lineation as well as the trend of the major thrusts, including CTT.&lt;/p&gt;&lt;p&gt;The modern shape of the Uzunakhmat thrust sheet is similar to an elongated triangle, pinching out northwest and expanding southeast. Cross-section balancing corrected for the amount of strain shows along-strike decreasing of shortening in the southeast direction. Total shortening varies from 35% to 55% between sections located about 15 km from each other. Such significant variation in shortening corresponds to variation in structural style with much more tight folds and more numerous thrusts for cross-sections with a higher amount of shortening. However, the restored length of all cross-sections is quite similar pointing to the approximately rectangular initial shape of the Uzunakhmat thrust sheet. Our interpretation is that during the Caledonian tectonic events, the Uzunakhmat thrust sheet was displaced in the northwest direction with accompanied thrusting and folding of rock units within the thrust sheet. These deformations formed the modern shape of the thrust sheet in accordance with the amount of shortening detected by cross-section balancing. This interpretation also implies that modern erosion did not significantly affect shape of the Uzunakhmat thrust sheet formed after the Caledonian deformation.&lt;/p&gt;&lt;p&gt;Khudoley, A.K., 1993. Structural and strain analyses of the middle part of the Talassian Alatau ridge (Middle Asia, Kirgiystan). J. Struct. Geol. 6, 693&amp;#8211;706.&lt;/p&gt;&lt;p&gt;Voytenko N.V., Khudoley A.K. Structural evolution of metamorphic rocks in the Talas Alatau, Tien Shan, Central Asia: Implication for early stages of the Talas-Ferghana Fault. // C. R. Geoscience. 2012. V. 344. P. 138&amp;#8211;148.&lt;/p&gt;

Integrated Cretaceous–Cenozoic plate tectonics and structural geology in southern Mexico

2020 ◽  
pp. SP504-2020-70
Author(s):  
Rod Graham ◽  
James Pindell ◽  
Diego Villagómez ◽  
Roberto Molina-Garza ◽  
James Granath ◽  
...  
Keyword(s):  
Cross Sections ◽  
Tectonic Evolution ◽  
Plate Tectonics ◽  
Plate Boundary ◽  
Structural Evolution ◽  
Thrust Belt ◽  
Cocos Plate ◽  
Southern Mexico ◽  
Arc Volcanism ◽  
Fold And Thrust Belt

AbstractThe structural evolution of southern Mexico is described in the context of its plate tectonic evolution and illustrated by two restored crustal scale cross-sections through Cuicateco and the Veracruz Basin and a third across Chiapas. We interpret the Late Jurassic–Early Cretaceous opening of an oblique hyper-stretched intra-arc basin between the Cuicateco Belt and Oaxaca Block of southern Mexico where Lower Cretaceous deep-water sediments accumulated. These rocks, together with the hyper-stretched basement beneath them and the Oaxaca Block originally west of them, were thrust onto the Cretaceous platform of the Cuicateco region during a Late Cretaceous–Eocene orogenic event. The mylonitic complex of the Sierra de Juárez represents this hyper-stretched basement, perhaps itself an extensional allochthon. The Chiapas fold-and-thrust belt is mainly Neogene in age. Shallowing of the subduction angle of the Cocos Plate in the wake of the Chortis Block, suggested by seismicity and migrating arc volcanism, is thought to play an important role in the development of the Chiapas fold-and-thrust belt itself, helping to explain the structural dilemma of a vertical transcurrent plate boundary fault (the Tonalá Fault) at the back of an essentially dip-slip fold-and-thrust belt.

Structural evolution in the northern part of the Moine thrust belt, NW Scotland

1980 ◽  
Vol 71 (2) ◽  
pp. 69-96 ◽  
Author(s):  
D. Elliott ◽  
M. R. W. Johnson
Keyword(s):  
Cross Sections ◽  
Structural Evolution ◽  
Thrust Belt ◽  
Sequence Diagrams ◽  
Western Margin ◽  
Contour Maps ◽  
Contact Aureoles

ABSTRACTFour balanced cross sections, supported by longitudinal sections, structure contour maps, stratigraphic separation diagrams and hangingwall sequence diagrams are keys to this interpretation of the Moine thrust, which forms the western margin of the Caledonides in NW Scotland. New basement and cover correlations between foreland and thrust belt give new slip estimates for the Moine thrust (∼ 77 km), the Loch More klippe (≥ 43 km), Glencoul sheet (20–25 km), Ben More sheet (∼28 km), Achall and Dundonnell ‘sheet II’ (∼28 km).Like other major thrusts the Moine thrust moved in a smooth or rough fashion at different places and times, and many structures are a footwall response to its passage. Widely developed duplexes vary in thickness so that the roof thrust is folded and occasionally faulted; many late Caledonian folds in the Moine metasediments are of this origin. The presence of igneous bodies with contact aureoles increased the propensity to rough slip and this, by causing thickening in the footwall to the Moine thrust, is partly responsible for the Assynt culmination.The previously accepted sequence of thrusting from foreland to hinterland, which has been deduced from the concept of ‘overstep’ of the Moine thrust across lower thrusts, is considered to be a misconception of thrust geometry. Instead, a ‘piggy-back’ sequence of thrusts, from higher to lower, is proposed.

Structural Cross-Section and Tectonic Model of the Southeastern Canadian Cordillera

1973 ◽  
Vol 10 (11) ◽  
pp. 1607-1620 ◽  
Author(s):  
R. B. Campbell
Keyword(s):  
Cross Sections ◽  
Rocky Mountains ◽  
Structural Evolution ◽  
Crystalline Basement ◽  
Canadian Rocky Mountains ◽  
Vertical Movements ◽  
Tectonic Model ◽  
Columbia Mountains ◽  
Thrust Sheets ◽  
Flanking Regions

Recent models for the structural evolution of the southern Canadian Rocky Mountains have emphasized 'thin-skinned' tectonics whereby thrust sheets piled up from west to east above a décollement on a passive crystalline basement. The concept implies that the more westernly Omineca Crystalline Belt, including granitoid gneiss believed to be basement more than 800 m.y. old, is allochthonous and has moved eastward by at least the amount of shortening in the thrust-faulted zone.Mildly deformed and metamorphosed stratified rocks in the northern Columbia Mountains (central Omineca Crystalline Belt) and adjacent Rocky Mountains permit construction of well-controlled structural and restored stratigraphic cross-sections, which show that the Crystalline Belt and Main Ranges were relatively uniformly uplifted by about 35 000 ft (11 km) whereas flanking regions experienced minor uplifts. Combined with other evidence this indicates that 'thick-skinned' tectonics with vertical movements of the entire crust affected the Omineca Crystalline Belt and the Main Ranges; major horizontal movements seem unnecessary. The Omineca Crystalline Belt is regarded as an autochthon in which the basement was extensively deformed and it is suggested that basement is deformed beneath the Main Ranges. The zone of thrusting and décollement above the basement is restricted to the Front Ranges and Foothills and may result from westward underthrusting of the craton.

The pre-Mesozoic basement underneath the Jura Mountains fold-and-thrust belt: an overview from models and maps

2020 ◽  
Author(s):  
Marc Schori ◽  
Anna Sommaruga ◽  
Jon Mosar
Keyword(s):  
Cross Sections ◽  
Structural Evolution ◽  
Rift System ◽  
European Alps ◽  
Thrust Belt ◽  
Jura Mountains ◽  
Basement Faults ◽  
Fold And Thrust Belt ◽  
Spatio Temporal ◽  
Basement Structures

&lt;p&gt;The Jura Mountains are a thin-skinned fold-and-thrust belt (FTB) in the northern foreland of the European Alps, extending over northern and western Switzerland and eastern France. The Jura FTB was detached in Triassic evaporites during Late Miocene and Pliocene compression. Prior to this, the pre-Mesozoic basement was intensely pre-structured by inherited faults that had been reactivated under changing stress fields during the Mesozoic and Cenozoic structural evolution of continental Europe. In order to understand the connection between thin-skinned FTB formation and pre-existing basement structures, we compiled boreholes and geological cross-sections across the Northern Alpine Foreland and derived elevation, thickness and erosion models of defined Mesozoic units and the top of the pre-Mesozoic basement.&lt;/p&gt;&lt;p&gt;Our models confirm the presence of basement faults concealed underneath the detached cover of the Jura Mountains. The pre-Mesozoic basement shows differences in structural altitudes resulting from partially overlapping lithospheric processes. They include graben formation during evolution of the European Cenozoic Rift System (ECRIS), flexural subsidence during Alpine forebulge development and lithospheric long-wavelength buckle folding. Faults in connection with these processes follow structural trends that suggest the reactivation of inherited Variscan and post-Variscan fault systems. We discuss the spatio-temporal imprint of lithospheric signatures on the pre-Mesozoic basement and their consequence on the formation of the Jura Mountains FTB. Untangling structures within the pre-Mesozoic basement leads us to a modern understanding of the long-term evolution of the detached Mesozoic cover. Furthermore, it allows us to improve the prediction of ages that are potentially preserved within the Mesozoic cover of the Jura FTB.&lt;/p&gt;

Unraveling the contribution of the western margin of the Altiplano plateau in North Chile (20°S) to Andean mountain-building

2020 ◽  
Author(s):  
Tania Habel ◽  
Robin Lacassin ◽  
Martine Simoes ◽  
Daniel Carrizo
Keyword(s):  
Cross Sections ◽  
Crustal Thickening ◽  
Thrust Belt ◽  
Seismic Profiles ◽  
Mountain Building ◽  
Buried Structures ◽  
Common View ◽  
Western Margin ◽  
The Andes ◽  
Fold And Thrust Belt

&lt;p&gt;&lt;span&gt;The Andes are the case example of an active Cordilleran-type orogen. It is generally admitted that, in the Central Andes (~20&amp;#176;S), mountain-building started ~50-60 Myr ago, close to the subduction margin, and then propagated eastward. Though suggested by some early geological cross-sections, the structures sustaining the uplift of the western flank of the Altiplano have been largely dismissed, and the most common view theorizes that the Andes grow only by east-vergent deformation along its eastern margin. However, recent studies emphasize the significant contribution of the West Andean front to mountain-building and crustal thickening, in particular at the latitude of Santiago de Chile (~33.5&amp;#176;S). The contribution of similar structures elsewhere along the Andes to the kinematics of the orogen is still poorly solved, because not yet well synthesized nor quantified. Here, we focus on the western margin of the Altiplano at 20&amp;#176;S, in the Atacama desert of northern Chile. We focus our work on two sites where structures are well exposed. &lt;br&gt;Our results confirm two main structures: (1) a major west-vergent thrust placing Andean Paleozoic basement over Mesozoic strata, and (2) a west-vergent fold-and-thrust-belt involving Mesozoic units. Once restored, we calculate a minimum of ~4 km of shortening across the sole ~10 km-wide outcropping fold-and-thrust-belt. Further west, structures of this fold-and-thrust-belt are unconformably buried under slightly deformed Cenozoic units, as revealed from seismic profiles. By comparing the scale of these buried structures to those investigated previously, we propose that the whole fold-and-thrust-belt has most probably absorbed ~15-20 km of shortening, sometime between ~68 Ma (youngest folded Mesozoic layers) and ~29 Ma (oldest unconformable Cenozoic layer). Preliminary (U-Th)/He thermochronological data suggest that basement exhumation by thrusting happened at the beginning of this ~40 Ma time span. Minor shortening affecting the mid-late Cenozoic deposits indicates that deformation continued after 29 Ma along the western Andean fold-and-thrust-belt, but remained limited compared to the more intense deformation during the Paleogene. Altogether, the data presented here will provide a quantitative evaluation of the contribution of the western margin of the Altiplano plateau to mountain-building at this latitude.&lt;/span&gt;&lt;/p&gt;

scholarly journals The structure of the northern Agrio fold and thrust belt (37°30’ S), Neuquén Basin, Argentina

2018 ◽  
Vol 45 (2) ◽  
pp. 249 ◽  
Author(s):  
Fernando Lebinson ◽  
Martín Turienzo ◽  
Natalia Sánchez ◽  
Vanesa Araujo ◽  
María Celeste D’Annunzio ◽  
...  
Keyword(s):  
Cross Sections ◽  
Sedimentary Cover ◽  
Structural Evolution ◽  
Normal Faults ◽  
Suitable Model ◽  
South American ◽  
Thrust Belt ◽  
Seismic Line ◽  
Fold And Thrust Belt ◽  
Fault Bend

The Agrio fold and thrust belt is a thick-skinned orogenic belt developed since Late Cretaceous in response to the convergence between the Nazca and South American plates. The integration of new structural field data and seismic line interpretation allowed us to create two balanced cross-sections, which help to analyse the geometry of both thick and thin-skinned structures, to calculate the tectonic shortenings and finally to discuss the main mechanisms that produced this fold and thrust belt. The predominantly NNW-SSE structures show varying wavelengths, and can be classified into kilometer-scale first order basement involved structures and smaller second, third and fourth order fault-related folds in cover rocks with shallower detachments. Thick-skinned structures comprise fault-bend folds moving into the sedimentary cover, mainly along Late Jurassic evaporites, which form basement wedges that transfer the deformation to the foreland. Thus, shortenings in both basement and cover rocks must be similar and consequently, by measuring the contraction accounted for thin-skinned structures, is possible to propose a suitable model for the thick skinned deformation. The balanced cross-sections indicate shortenings of 11.2 km (18%) for the northern section and 10.9 km (17.3%) for the southern section. These values are different from the shortenings established by previous works in the region, reflecting differences in the assumed model to explain the basement-involved structures. According to our interpretation, the structural evolution of this fold and thrust belt was controlled by major basement-involved thrust systems with subordinate influence of inversion along pre-existing normal faults during the Andean compression.

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