Calcite twinning strains associated with Laramide uplifts, Wyoming Province

ABSTRACT We report the results of 167 calcite twinning strain analyses (131 limestones and 36 calcite veins, n = 7368 twin measurements)t from the Teton–Gros Ventre (west; n = 21), Wind River (n = 43), Beartooth (n = 32), Bighorn (n = 32), and Black Hills (east; n = 11) Laramide uplifts. Country rock limestones record only a layer-parallel shortening (LPS) strain fabric in many orientations across the region. Synorogenic veins record both vein-parallel shortening (VPS) and vein-normal shortening (VNS) fabrics in many orientations. Twinning strain overprints were not observed in the limestone or vein samples in the supracrustal sedimentary veneer (i.e., drape folds), thereby suggesting that the deformation and uplift of Archean crystalline rocks that form Laramide structures were dominated by offset on faults in the Archean crystalline basement and associated shortening in the midcrust. The twinning strains in the pre-Sevier Jurassic Sundance Formation, in the frontal Prospect thrust of the Sevier belt, and in the distal (eastern) foreland preserve an LPS oriented approximately E-W. This LPS fabric is rotated in unique orientations in Laramide uplifts, suggesting that all but the Bighorn Mountains were uplifted by oblique-slip faults. Detailed field and twinning strain studies of drape folds identified second-order complexities, including: layer-parallel slip through the fold axis (Clarks Fork anticline), attenuation of the sedimentary section and fold axis rotation (Rattlesnake Mountain), rotation of the fold axis and LPS fabric (Derby Dome), and vertical rotations of the LPS fabric about a horizontal axis with 35% attenuation of the sedimentary section (eastern Bighorns). Regional cross sections (E-W) across the Laramide province have an excess of sedimentary veneer rocks that balance with displacement on a detachment at 30 km depth and perhaps along the Moho discontinuity at 40 km depth. Crustal volumes in the Wyoming Province balance when deformation in the western hinterland is included.

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Influence of basement rocks on fluid evolution during multiphase deformation: the example of the Estamariu thrust in the Pyrenean Axial Zone

10.5194/se-2020-65 ◽

2020 ◽

Author(s):

Daniel Muñoz-López ◽

Gemma Alías ◽

David Cruset ◽

Irene Cantarero ◽

Cédric M. Jonh ◽

...

Keyword(s):

Sedimentary Cover ◽

Crystalline Basement ◽

Normal Faults ◽

Published Data ◽

Fluid Migration ◽

Rock Interaction ◽

Fluid Chemistry ◽

Vein Formation ◽

Basement Rocks ◽

Calcite Veins

Abstract. Calcite veins precipitated in the Estamariu thrust during two tectonic events decipher the temporal and spatial relationships between deformation and fluid migration in a long-lived thrust and determine the influence of basement rocks on the fluid chemistry during deformation. Structural and petrological observations constrain the timing of fluid migration and vein formation, whilst geochemical analyses (δ13C, δ18O, 87Sr/86Sr, clumped isotope thermometry and elemental composition) of the related calcite cements and host rocks indicate the fluid origin, pathways and extent of fluid-rock interaction. The first tectonic event, recorded by calcite cements Cc1a and Cc2, is related to the Alpine reactivation of the Estamariu thrust, and is characterized by the migration of meteoric fluids, heated at depth (temperatures between 56 and 98 °C) and interacted with crystalline basement rocks before upflowing through the thrust zone. During the Neogene extension, the Estamariu thrust was reactivated and normal faults and shear fractures with calcite cements Cc3, Cc4 and Cc5 developed. Cc3 and Cc4 precipitated from hydrothermal fluids (temperatures between 127 and 208 °C and between 102 and 167 °C, respectively) derived from crystalline basement rocks and expelled through fault zones during deformation. Cc5 precipitated from low temperature meteoric waters percolating from the surface through small shear fractures. The comparison between our results and already published data in other structures from the Pyrenees suggests that regardless of the origin of the fluids and the tectonic context, basement rocks have a significant influence on the fluid chemistry, particularly on the 87Sr/86Sr ratio. Accordingly, the cements precipitated from fluids interacted with crystalline basement rocks have significantly higher 87Sr/86Sr ratios (> 0.710) with respect to those precipitated from fluids that have interacted with the sedimentary cover (

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Long-term burial history and orogenic-scale fluid flow depicted from stable isotopes and stylolite paleopiezometry in the Umbria-Marches arcuate belt (Northern Apennines, Italy).

10.5194/egusphere-egu2020-19184 ◽

2020 ◽

Author(s):

Nicolas Beaudoin ◽

Aurélie Labeur ◽

Olivier Lacombe ◽

Guilhem Hoareau ◽

Marta Marchegiano ◽

...

Keyword(s):

Fluid Flow ◽

Local Maximum ◽

Geothermal Gradient ◽

Burial Depth ◽

Fold Axis ◽

Clumped Isotopes ◽

Burial History ◽

Fluid System ◽

Calcite Veins ◽

Absolute Dating

Faults, joints and stylolites are ubiquitous features in fold-and-thrust belts, and have been used for decades to reconstruct the past fluid flow (or plumbing system) at the scale of folded reservoirs/basins. The textural and geochemical study of the minerals filling the fractures makes it possible to unravel the history of fluid flow in an orogen, when combined with a knowledge of the burial history and/or of the paleothermal gradient. In most cases, the latter derives from the former, itself often argued over, limiting the interpretations of past fluid temperatures. Yet, recent methodological developments applied to carbonates and calcite fillings provide new perspectives for a more accurate reconstruction of the temperature, pressure and timing of the fluids that were present in the strata at the time they deformed, at every stage of fold development. Indeed, the temperature at which fluids precipitated can be obtained by &#916;47CO2&#160;clumped isotopes while the timing of calcite precipitation in veins and faults is given by U-Pb absolute dating. Also, the maximum burial depth of strata before contraction can be estimated using sedimentary stylolite paleopiezometry, hence in a way free of any consideration about the geothermal gradient. These techniques were jointly applied at the scale of the Umbria-Marches arcuate belt (UMAR, Northen Apennines, Italy). Mesoscale faults and vein sets were measured and sampled in the Cretaceous-Eocene rocks. Focusing on those fractures that developed during Layer Parallel Shortening (LPS, i.e. oriented NE-SW to E-W) and during folding (i.e. oriented parallel to local fold axis), paleofluid sources, temperatures and timing were reconstructed using U-Pb absolute dating, &#916;47CO2 clumped isotopes as well as &#948;18O, &#948;13C, and 87/86Sr signatures of calcite veins. Results show a regional divide in the fluid system, with most of the belt including the foreland recording a fluid system involving basinal brines resulting at various degree from fluid-rock interactions (FRI) between pristine marine fluids (&#948;18Ofluid= 0&#8240; SMOW) and surrounding limestones (&#948;18Ofluid= 10&#8240; SMOW). Precipitation temperatures (35&#176;C to 75&#176;C) appear consistent with the burial history unraveled by sedimentary stylolite roughness paleopiezometry (600 m to 1500m in the range) and estimated geothermal gradient (23&#176;C/km, Caricchi et al., 2004). As the degree of FRI increases forelandward, we propose a lateral, strata-bound, squeegee-type migration of fluids during folding and thrusting. In the western hinterland however, the fluid system rather involves hydrothermal fluids with a higher degree of FRI, the corresponding precipitation temperatures (100&#176;C to 130&#176;C) of which are inconsistent with local maximum burial (1500m). As the Sr radiogenic signatures preclude any deep origin of the fluids, we propose that the fluid system prevailing in the hinterland during LPS reflects the eastward migration of formational fluids originating from the Tuscan basin, located west from the UMAR, where studied Cretaceous rocks were buried under more than 4 km of sediments during the Miocene. Beyond being the first combination of paleofluid geochemistry and burial estimates through paleopiezometry, this fluid flow model illustrates how the large scale structures may control the fluid system at the scale of a mountain belt.

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Geochemistry and origin of Archean granites from the Black Hills, South Dakota

Canadian Journal of Earth Sciences ◽

10.1139/e90-005 ◽

1990 ◽

Vol 27 (1) ◽

pp. 57-71 ◽

Cited By ~ 8

Author(s):

D. C. Gosselin ◽

J. J. Papike ◽

C. K. Shearer ◽

Z. E. Peterman ◽

J. C. Laul

Keyword(s):

Rare Earth ◽

South Dakota ◽

Partial Melting ◽

Residence Time ◽

Earth Element ◽

Black Hills ◽

Isotopic Data ◽

Tectonic Environment ◽

Sedimentary Source ◽

Wyoming Province

The Little Elk Granite (2549 Ma) and granite at Bear Mountain (BMG) (~2.5 Ga) of the Black Hills formed as a result of a collisional event along the eastern margin of the Wyoming Province during the late Archean. Geochemical modelling and Nd isotopic data indicate that the Little Elk Granite was generated by the partial melting of a slightly enriched (εNd = −1.07 to −3.69) granodioritic source that had a crustal residence time of at least 190 Ma. The medium-grained to pegmatitic, peraluminous, leucocratic BMG was produced by melting a long-lived (>600 Ma), compositionally variable, enriched (εNd = −7.6 to −12.3) crustal source. This produced a volatile-rich, rare-earth-element-poor magma that experienced crystal–melt–volatile fractionation, which resulted in a lithologically complex granite.The production of volatile-rich granites, such as the BMG and the younger Harney Peak Granite (1715 Ma), is a function of the depositional and post-depositional tectonic environment of the sedimentary source rock. These environments control protolith composition and the occurrence of dehydration and melting reactions that are necessary for the generation of these volatile-rich leucocratic granites. These types of granites are commonly related to former continental–continental accretionary boundaries, and therefore their occurrence may be used as signatures of ancient continental suture zones.

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Early Archean to Mesoproterozoic evolution of the Wyoming Province: Archean origins to modern lithospheric architecture

Canadian Journal of Earth Sciences ◽

10.1139/e03-054 ◽

2003 ◽

Vol 40 (10) ◽

pp. 1357-1374 ◽

Cited By ~ 81

Author(s):

Kevin R Chamberlain ◽

Carol D Frost ◽

B Ronald Frost

Keyword(s):

Black Hills ◽

Arc Magmatism ◽

Crustal Growth ◽

Crustal Layer ◽

Oregon Trail ◽

Sierra Madre ◽

Cumulative Processes ◽

Wyoming Province ◽

Lower Crustal ◽

East West

Local preservation of 3.63.0 Ga gneisses and widespread isotopic evidence for crust of this age incorporated into younger plutons indicates that the Wyoming Province was a [Formula: see text] 100 000 km2 middle Archean craton, which was modified by late Archean magmatism and tectonism and Proterozoic extension and rifting. On the basis of differences in late Archean histories, the Wyoming Province is subdivided into five subprovinces: three in the Archean core, (1) the Montana metasedimentary province, (2) the Bighorn subprovince, and (3) the Sweetwater subprovince, and two Archean terrains that may be allochthonous to the 3.0 Ga craton, (4) the Sierra Madre Medicine Bow block, and (5) the Black Hills Hartville block. A thick, fast lower crustal layer, imaged by Deep Probe, corresponds geographically with the Bighorn subprovince and may be an underplate associated with ca. 2.70 Ga mafic magmatism. The Sweetwater subprovince is characterized by an eastwest tectonic grain that was established by three or more temporally related, late Archean, pulses of basin development, shortening, and arc magmatism. This tectonic grain, including the 2.62 Ga Oregon Trail structure, controlled the locations and orientations of Proterozoic rifting and Laramide uplifts. The present-day lithospheric architecture of the Wyoming Province is the result of cumulative processes of crustal growth and tectonic modification; lithospheric contrasts have apparently persisted for billions of years. If there has been any net crustal growth of the Wyoming Province since 3.0 Ga, it has involved a combination of mafic underplating and arc magmatism.

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Precambrian crystalline basement at the head of Victoria Fjord, North Greenland

Rapport Grønlands Geologiske Undersøgelse ◽

10.34194/rapggu.v126.7907 ◽

1985 ◽

Vol 126 ◽

pp. 11-16

Author(s):

N Henriksen ◽

H.F Jepsen

Keyword(s):

Lower Cambrian ◽

Small Area ◽

Crystalline Rocks ◽

Crystalline Basement ◽

Amphibolite Facies ◽

Isotopic Age ◽

Late Proterozoic ◽

Inland Ice ◽

North Greenland ◽

Age Determinations

Precambrian granites and gneisses outcrop below late Proterozoic and Lower Cambrian sediments in a small area at the margin of the Inland Ice. The exposed crystalline rocks comprise orthogneisses with scattered amphibolite bands, and occasional horizons of metasediments. The rocks are folded, somewhat migmatised and metamorphosed under amphibolite facies conditions. Samples for Rb-Sr whole rock and Zr isotopic age determinations have been collected.

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

Canadian Journal of Earth Sciences ◽

10.1139/e73-154 ◽

1973 ◽

Vol 10 (11) ◽

pp. 1607-1620 ◽

Cited By ~ 16

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.

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EUCLIDIAN DISTANCE TRANSFORMATION, MAIN AXIS ROTATION AND NOISY DILITATION SUPPORTED CROSS-SECTION CLASSIFICATION WITH CONVOLUTIONAL NEURAL NETWORKS

Proceedings of the Design Society ◽

10.1017/pds.2021.140 ◽

2021 ◽

Vol 1 ◽

pp. 1401-1410

Author(s):

Martin Denk ◽

Klemens Rother ◽

Tobias Höfer ◽

Jan Mehlstäubl ◽

Kristin Paetzold

Keyword(s):

Topology Optimization ◽

Cross Section ◽

Cross Sections ◽

Computer Aided Design ◽

Laser Scanning ◽

Main Axis ◽

Distance Transformation ◽

The Cross ◽

Axis Rotation ◽

Polygon Meshes

AbstractPolygon meshes and particularly triangulated meshes can be used to describe the shape of different types of geometry such as bicycles, bridges, or runways. In engineering, such polygon meshes can be supplied as finite element meshes, resulting from topology optimization or from laser scanning. Especially from topology optimization, frame-like polygon meshes with slender parts are typical and often have to be converted into a CAD (Computer-Aided Design) format, e.g., for further geometrical detailing or performing additional shape optimization. Especially for such frame-like geometries, CAD designs are constructed as beams with cross-sections and beam-lines, whereby the cross-section is extruded along the beam-lines or beam skeleton. One major task in the recognition of beams is the classification of the cross-section type such as I, U, or T, which is addressed in this article. Therefore, a dataset consisting of different cross-sections represented as binary images is created. Noisy dilatation, the distance transformation, and main axis rotation are applied to these images to increase the robustness and reduce the necessary amount of samples. The resulting images are applied to a convolutional neuronal network.

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Does the Owl Creek fault zone of north-central Wyoming extend to the Black Hills of South Dakota? Implications for basement architecture of the Wyoming Province

The Mountain Geologist ◽

10.31582/rmag.mg.58.1.27 ◽

2021 ◽

Vol 58 (1) ◽

pp. 27-37

Author(s):

Jeffrey W. Bader

Keyword(s):

South Dakota ◽

Fault Zone ◽

Plate Tectonics ◽

Black Hills ◽

Powder River Basin ◽

Foreland Basins ◽

North Central ◽

North American Cordillera ◽

The North ◽

Wyoming Province

The North Owl Creek fault is an E–W-striking, basement-rooted Laramide structure located in the Owl Creek Mountains of north-central Wyoming that likely has Precambrian origins. It is defined by a rectilinear zone of deformation that extends eastward into the subsurface where it is postulated to intersect the Kaycee fault zone of the western Powder River Basin, and perhaps extends into western South Dakota along the Dewey fault zone. Several localized basement-rooted wrench zones have been identified in the foreland of the North American Cordillera; however, identification of more regional zones has been minimal. The presence of larger fault zones that cut nearly the entire Archean basement across the Wyoming Province has implications for Precambrian plate tectonics and structural inheritance in foreland basins such as the Powder River. This paper presents results of a structural analysis that tests this hypothesis.

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Application of geophysical and hydrogeological analyses to predict water and hydrocarbon entry to the T5 Tunnel, west Iran

Quarterly Journal of Engineering Geology and Hydrogeology ◽

10.1144/qjegh2021-132 ◽

2021 ◽

pp. qjegh2021-132

Author(s):

Mohammad Moradi ◽

Morteza Mozafari ◽

Mohammad Javad Bolourchi ◽

Alireza Aliyari ◽

Nikolay A. Palshin ◽

...

Keyword(s):

Cross Sections ◽

Transfer Functions ◽

Vapour Phase ◽

Water Entry ◽

Gradient Algorithm ◽

Asmari Formation ◽

Fold Axis ◽

Field Works ◽

Under Construction ◽

Gurpi Formation

The Garmsiri Project, including the 4.5 km long T5 Tunnel, is under construction in western Iran. The T5 tunnel passes through the NW-SE trending Emam Hasan Anticline (EHA), perpendicular to the fold axis. The fold is mainly composed of the marlstone and argillaceous limestone layers of Cretaceous to Miocene age, incorporating the Pabdeh-Gurpi Formation, karst limestone of the Asmari Formation, and marlstone and gypsum of the Gachsaran Formation. There was a risk of water entry into the tunnel since it was constructed below the regional groundwater table elevation. In addition the entry of hydrocarbons, in either liquid or vapour phase, to the tunnel was possible due to the presence of numerous active bitumen mines in the vicinity of the anticline. To predict the risk of water or hydrocarbon entry geological and hydrogeological analyses together with the Audio Magnetotelluric (AMT) method were applied. Based on the field works, resistivity and geological cross sections were provided along the tunnel path. Several boreholes were drilled along the tunnel route and watertable elevation, Rock Quality Designation (RQD) and permeability values were measured. To determine a broad range of features related to the anticline, 55 AMT stations were positioned along the tunnel route. Dimensionality analysis confirmed 2D dimensionality of the AMT transfer functions, which allowed to apply the 2D bimodal inversion using a non-linear conjugate gradient algorithm. Integration of the geological and hydrogeological data with the resistivity model resulted in a more detailed geological section along the tunnel, including watertable elevation and identification of highly conductive zones in which bitumen migrated. It was predicted that water entry would be observed through the Asmari Formation and also that elevated H2S concentrations would be encountered during drilling in the anomalous conductive zones. Monitoring results and field observations gained during the tunnel construction were compared by the predictions.

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