scholarly journals Supplemental Material: Plate boundary trench retreat and dextral shear drive intracontinental fault-slip histories: Neogene dextral faulting across the Gabbs Valley and Gillis Ranges, Central Walker Lane, Nevada

2020 ◽  
Author(s):  
J. Lee ◽  
et al.
Keyword(s):  
Hanging Wall ◽  
Plate Boundary ◽  
Normal Fault ◽  
Data Sets ◽  
Geologic Mapping ◽  
Walker Lane ◽  
Geologic Map ◽  
Dextral Shear ◽  
Layer I ◽  
Intersection Line

<div>Figure 3. Layer A. Shaded relief map of the Gabbs Valley, Gillis, and Wassuk ranges, Nevada. Layer B. Simplified geologic map of the Gabbs Valley, Gillis, and Wassuk ranges. Sources of geologic mapping: Bingler (1978); Hardyman (1980); Stewart et al. (1981); Ekren and Byers (1985a, 1985b, 1986a, 1986b); Dilles (1992); Hoxey et al. (2020); this study. Layer C. Geographic names for major mountains, valleys, canyons, flats, washes, and lakes; fault names, and other labels. Layer D. Locations photographs (see Fig. 5), cross-section lines (see Fig. 6), and <sup>40</sup>Ar/<sup>39</sup>Ar sample locations with ages (see Table 1). Layers E–J. Southern paleovalley wall contacts and measured dextral offsets for paleovalley infilling units Obmg, Osp, Mrc, Mrl, and Mal, respectively. Layer I. Southern contact of unit Mlf and measured dextral offset. Layer K. Intersection line defined by normal fault–hanging-wall contact between units Mlf and Me and measured dextral offset. Maps, labels, and data sets are organized in a series of layers that may be viewed separately or in combination using the capabilities of the Acrobat (PDF) layering function (click “Layers” icon along vertical bar on left side of window for display of available layers; turn layers on or off by clicking the box that encompasses the layer label located within the gray box in the upper right part of the figure). Figure 3 is intended to be viewed at a width of 64 cm.<br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div>

scholarly journals Supplemental Material: Plate boundary trench retreat and dextral shear drive intracontinental fault-slip histories: Neogene dextral faulting across the Gabbs Valley and Gillis Ranges, Central Walker Lane, Nevada

2020 ◽  
Author(s):  
J. Lee ◽  
et al.
Keyword(s):  
Hanging Wall ◽  
Plate Boundary ◽  
Normal Fault ◽  
Data Sets ◽  
Geologic Mapping ◽  
Walker Lane ◽  
Geologic Map ◽  
Dextral Shear ◽  
Layer I ◽  
Intersection Line

<div>Figure 3. Layer A. Shaded relief map of the Gabbs Valley, Gillis, and Wassuk ranges, Nevada. Layer B. Simplified geologic map of the Gabbs Valley, Gillis, and Wassuk ranges. Sources of geologic mapping: Bingler (1978); Hardyman (1980); Stewart et al. (1981); Ekren and Byers (1985a, 1985b, 1986a, 1986b); Dilles (1992); Hoxey et al. (2020); this study. Layer C. Geographic names for major mountains, valleys, canyons, flats, washes, and lakes; fault names, and other labels. Layer D. Locations photographs (see Fig. 5), cross-section lines (see Fig. 6), and <sup>40</sup>Ar/<sup>39</sup>Ar sample locations with ages (see Table 1). Layers E–J. Southern paleovalley wall contacts and measured dextral offsets for paleovalley infilling units Obmg, Osp, Mrc, Mrl, and Mal, respectively. Layer I. Southern contact of unit Mlf and measured dextral offset. Layer K. Intersection line defined by normal fault–hanging-wall contact between units Mlf and Me and measured dextral offset. Maps, labels, and data sets are organized in a series of layers that may be viewed separately or in combination using the capabilities of the Acrobat (PDF) layering function (click “Layers” icon along vertical bar on left side of window for display of available layers; turn layers on or off by clicking the box that encompasses the layer label located within the gray box in the upper right part of the figure). Figure 3 is intended to be viewed at a width of 64 cm.<br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div>

scholarly journals Supplemental Material: Plate boundary trench retreat and dextral shear drive intracontinental fault-slip histories: Neogene dextral faulting across the Gabbs Valley and Gillis Ranges, Central Walker Lane, Nevada

2020 ◽  
Author(s):  
J. Lee ◽  
et al.
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Plate Boundary ◽  
Fault Slip ◽  
Cross Sectional ◽  
Walker Lane ◽  
Dextral Shear ◽  
The Cross

<div>Figure 6. Interpretative cross sections illustrating the cross-sectional geometry of several paleovalleys. See Figure 3 for location of all cross sections and Figure 8 for location of cross section CCʹ. Cross sections AAʹ and BBʹ are plotted at the same scale, and cross section CCʹ is plotted at a smaller scale. Figure 6 is intended to be viewed at a width of 45.1 cm.</div>

scholarly journals Supplemental Material: Plate boundary trench retreat and dextral shear drive intracontinental fault-slip histories: Neogene dextral faulting across the Gabbs Valley and Gillis Ranges, Central Walker Lane, Nevada

2020 ◽  
Author(s):  
J. Lee ◽  
et al.
Keyword(s):  
Probability Density ◽  
Plate Boundary ◽  
Analytical Techniques ◽  
Fault Slip ◽  
Walker Lane ◽  
Analytical Results ◽  
Dextral Shear

<div>Provides a description of 40Ar/39Ar analytical techniques, 40Ar/39Ar analytical results, and includes supporting age spectra and probability density plots of ages. <br></div>

Using 2D long-streamer seismic waveform tomography to decipher sedimentary processes surrounding a forearc fault offshore Alaska

2021 ◽  
Author(s):  
Amin Kahrizi ◽  
Matthias Delescluse ◽  
Mathieu Rodriguez ◽  
Pierre-Henri Roche ◽  
Anne Bécel ◽  
...  
Keyword(s):  
Mass Transport ◽  
Hanging Wall ◽  
Plate Boundary ◽  
Normal Fault ◽  
P Wave ◽  
Fault System ◽  
Fault Activity ◽  
Seismic Waveform ◽  
Waveform Tomography ◽  
Mass Transport Deposits

&lt;p&gt;Acoustic full-waveform inversion (FWI), or waveform tomography, involves use of both phase and amplitude of the recorded compressional waves to obtain a high-resolution P-wave velocity model of the propagation medium. Recent theoretical and computing advances now allow the application of this highly non-linear technique to field data. This led to common use of the FWI for industrial purposes related to reservoir imaging, physical properties of rocks, and fluid flow. Application of FWI in the academic domain has, so far, been limited, mostly because of the lack of adequate seismic data. Modern multichannel seismic (MCS) reflection data acquisition now&amp;#160; have long offsets which, in some cases, enable constraining FWI-derived subsurface velocities at a significant enough depth to be useful for structural or tectonic purposes.&lt;/p&gt;&lt;p&gt;In this study, we show how FWI can help decipher the record of a fault activity through time at the Shumagin Gap in Alaska. The MCS data were acquired on R/V Marcus G. Langseth during the 2011 ALEUT cruise using two 8-km-long seismic streamers and a 6600 cu. in. tuned airgun array. One of the most noticeable reflection features imaged on two profiles is a large, landward-dipping normal fault in the overriding plate; a structural configuration making the area prone to generating both transoceanic and local tsunamis, including from landslides. This fault dips ~40&amp;#176;- 45&amp;#176;, cuts the entire crust and connects to the plate boundary fault at ~35 km depth, near the intersection of the megathrust with the forearc mantle wedge. The fault system reaches the surface at the shelf edge 75 km from the trench and forms the ~6-km deep Sanak basin. However, the record of the recent fault activity remains unclear as contouritic currents tend to be trapped by the topography created by faults, even after they are no longer active.&amp;#160; Erosion surfaces and onlaps from contouritic processes as well as gravity collapses and mass transport deposits result in a complex sedimentary record that make it challenging to evaluate the fault activity using conventional MCS imaging alone. The long streamers used facilitated recording of refraction arrivals in the targeted continental slope area, which permitted running streamer traveltime tomography followed by FWI to produce coincident detailed velocity profiles to complement the reflection sections. We performed FWI imaging on two 40-km-long sections of the ALEUT lines crossing the Sanak basin. The images reveal low velocities of mass transport deposits as well as velocity inversions that may indicate mechanically weak layers linking some faults to gravity sliding on a d&amp;#233;collement. One section also shows a velocity inversion in continuity to a bottom simulating reflector (BSR) only partially visible in the reflection image. The BSR velocity anomaly abruptly disappears across the main normal fault suggesting either an impermeable barrier or a lack of trapped fluids/gas in the hanging wall.&lt;/p&gt;

scholarly journals Supplemental Material: Plate boundary trench retreat and dextral shear drive intracontinental fault-slip histories: Neogene dextral faulting across the Gabbs Valley and Gillis Ranges, Central Walker Lane, Nevada

2020 ◽  
Author(s):  
J. Lee ◽  
et al.
Keyword(s):  
Probability Density ◽  
Plate Boundary ◽  
Analytical Techniques ◽  
Fault Slip ◽  
Walker Lane ◽  
Analytical Results ◽  
Dextral Shear

<div>Provides a description of 40Ar/39Ar analytical techniques, 40Ar/39Ar analytical results, and includes supporting age spectra and probability density plots of ages. <br></div>

scholarly journals Supplemental Material: Plate boundary trench retreat and dextral shear drive intracontinental fault-slip histories: Neogene dextral faulting across the Gabbs Valley and Gillis Ranges, Central Walker Lane, Nevada

2020 ◽  
Author(s):  
J. Lee ◽  
et al.
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Plate Boundary ◽  
Fault Slip ◽  
Cross Sectional ◽  
Walker Lane ◽  
Dextral Shear ◽  
The Cross

<div>Figure 6. Interpretative cross sections illustrating the cross-sectional geometry of several paleovalleys. See Figure 3 for location of all cross sections and Figure 8 for location of cross section CCʹ. Cross sections AAʹ and BBʹ are plotted at the same scale, and cross section CCʹ is plotted at a smaller scale. Figure 6 is intended to be viewed at a width of 45.1 cm.</div>

THE NATIONAL GEOLOGIC MAP DATABASE -- A RESOURCE FOR GEOLOGIC MAPPING

2016 ◽  
Author(s):  
David R. Soller ◽  
◽  
Nancy R. Stamm ◽  
Robert C. Wardwell ◽  
Christopher P. Garrity
Keyword(s):  
Geologic Mapping ◽  
Geologic Map

Geologic Map of the Park Reservoir Quadrangle, Sheridan County, Wyoming

2020 ◽  
Vol 57 (4) ◽  
pp. 375-388
Author(s):  
Ryan Bessen ◽  
Jennifer Gifford ◽  
Zack Ledbetter ◽  
Sean McGuire ◽  
Kyle True ◽  
...  
Keyword(s):  
Structural Features ◽  
Geologic Mapping ◽  
Rock Types ◽  
Basement Rocks ◽  
Geologic Maps ◽  
Geologic Map ◽  
Tear Fault ◽  
Mapping Techniques ◽  
Wyoming Province ◽  
Bighorn Mountains

This project involved the construction of a detailed geologic map of the Park Reservoir, Wyoming 7.5-Minute Quadrangle (Scale 1:24,000). The Quadrangle occurs entirely in the Bighorn National Forest, which is a popular recreation site for thousands of people each year. This research advances the scientific understanding of the geology of the Bighorn Mountains and the Archean geology of the Wyoming Province. Traditional geologic mapping techniques were used in concert with isotopic age determinations. Our goal was to further subdivide the various phases of the 2.8–3.0 Ga Archean rocks based on their rock types, age, and structural features. This research supports the broader efforts of the Wyoming State Geological Survey to complete 1:24,000 scale geologic maps of the state. The northern part of the Bighorn Mountains is composed of the Bighorn batholith, a composite complex of intrusive bodies that were emplaced between 2.96–2.87 Ga. Our mapping of the Park Reservoir Quadrangle has revealed the presence of five different Archean quartzofeldspathic units, two sets of amphibolite and diabase dikes, a small occurrence of the Cambrian Flathead Sandstone, two Quaternary tills, and Quaternary alluvium. The Archean rock units range in age from ca. 2.96–2.75 Ga, the oldest of which are the most ancient rocks yet reported in the Bighorn batholith. All the Archean rocks have subtle but apparent planar fabric elements, which are variable in orientation and are interpreted to represent magmatic flow during emplacement. The Granite Ridge tear fault, which is the northern boundary of the Piney Creek thrust block, is mapped into the Archean core as a mylonite zone. This relationship indicates that the bounding faults of the Piney Creek thrust block were controlled by weak zones within the Precambrian basement rocks.

Discovery of a Jurassic Porphyry Copper Belt, Pangui Area, Southern Ecuador

SEG Discovery ◽  
2000 ◽  
pp. 1-15
Author(s):  
IAN R. GENDALL ◽  
LUIS A. QUEVEDO ◽  
RICHARD H. SILLITOE ◽  
RICHARD M. SPENCER ◽  
CARLOS O. PUENTE ◽  
...  
Keyword(s):  
Porphyry Copper ◽  
Hanging Wall ◽  
Foreland Basin ◽  
Sulfide Mineral ◽  
The Philippines ◽  
Normal Faults ◽  
Geologic Mapping ◽  
Copper Mineralization ◽  
Argillic Alteration ◽  
Infill Drilling

ABSTRACT Grassroots exploration has led to discovery of 10 porphyry copper prospects in the previously unexplored Jurassic arc of southeastern Ecuador. The prospects are located in steep, wet, jungle-covered terrain in the Pangui area, part of the Cordillera del Cóndor. The exploration program, initially mounted in search of gold in the Oriente foreland basin, employed panned-concentrate drainage sampling. Follow-up of the resulting anomalies utilized soil sampling combined with rock-chip sampling and geologic mapping of the restricted creek outcrops. Scout and infill drilling of two of the prospects, San Carlos and Panantza, has shown hypogene mineralization averaging 0.5 to 0.7 percent Cu overlain by thin (averaging &lt;30 m) zones of chalcocite enrichment or oxidized copper mineralization. The prospects are centered on small, composite granocliorite to monzogranite porphyry stocks that cut the Zamora batholith or, in one case, a satellite pluton. The batholith is emplaced into Jurassic volcanosedimentary formations, which concealed Triassic extensional half-grabens before being incorporated into the Subandean fold-thrust belt along the western margin of the Oriente basin. North- and northwest-striking normal faults in the hanging wall of a major north-striking fault zone controlled the locations of most of the porphyry centers. K silicate and variably overprinted intermediate argillic alteration, containing chalcopyrite as the principal sulfide mineral, characterize the central parts of most of the porphyry prospects and grade outward to pyrite-dominated propylitic halos. Overprinted sericitic alteration is generally less widely developed, although apparently shallower erosion at the Warintza and Wawame prospects resulted in preservation of extensive pyrite-rich sericitic zones. All the prospects contain appreciable (60–250 ppm) molybdenum, but gold tenors are low except at Panantza and Wawame (~0.15 and 0.2 g/t, respectively). Supergene oxidation and chalcocite enrichment zones are immature because of inhibition by the rapid erosion prevalent in the Pangui area. Supergene profiles attain their maximum development on ridge crests but are essentially absent along major creeks. Discovery of the Pangui belt, along with other recently defined porphyry copper systems in northern Perú, Indonesia, and the Philippines, underscores yet again the efficacy of drainage geochemistry as an exploration technique in tropical and subtropical arc terranes as well as the outstanding potential for additional exposed deposits in poorly explored parts of the circum-Pacific region.

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