Pilot Mountain Research Articles

Camera Trap Methods and Drone Thermal Surveillance Provide Reliable, Comparable Density Estimates of Large, Free-Ranging Ungulates.

Camera traps and drone surveys both leverage advancing technologies to study dynamic wildlife populations with little disturbance. Both techniques entail strengths and weaknesses, and common camera trap methods can be confounded by unrealistic assumptions and prerequisite conditions. We compared three methods to estimate the population density of white-tailed deer (Odocoileus virgnianus) in a section of Pilot Mountain State Park, NC, USA: (1) camera trapping using mark-resight ratios or (2) N-mixture modeling and (3) aerial thermal videography from a drone platform. All three methods yielded similar density estimates, suggesting that they converged on an accurate estimate. We also included environmental covariates in the N-mixture modeling to explore spatial habitat use, and we fit models for each season to understand temporal changes in population density. Deer occurred in greater densities on warmer, south-facing slopes in the autumn and winter and on cooler north-facing slopes and in areas with flatter terrain in the summer. Seasonal density estimates over two years suggested an annual cycle of higher densities in autumn and winter than in summer, indicating that the region may function as a refuge during the hunting season.

Fire in central Piedmont as recorded by fire scars at Pilot Mountain State Park, NC

ABSTRACTFire has been well studied in the Appalachians but has not been well characterized within Piedmont xeric forests. Herein we describe a dendrochronological study at Pilot Mountain State Park, NC addressing the following: How frequently did this forest experience fire? Is fire occurrence correlated with drought conditions? How did fire activity change with the onset of suppression? How does the fire regime compare with xeric Appalachian forests and prior models of Piedmont fire frequency? Seventy samples documented 34 fires between 1849–2014. The first fire occurred in 1891 and the first two-scar fire occurred in 1904. The composite Mean Fire Interval and Weinbull Median Interval pre-suppression (pre-1930; 2.36 and 2.25 years, respectively) were almost half that of the suppression period (post-1930; 4.56 and 4.09 years, respectively). With suppression, the Decadal Fire Index and mean number of scars per fire declined significantly (p ≤ 0.05 and ≤ 0.001). The Pre-suppression Filtered Composite MFI (4.2 years) was lower than any reported for the Appalachians and agrees with previous model predictions. Fire activity was strongly correlated with drought 2 years prior, before suppression but not afterward. As documented here, fire scars on xeric forest pines may contain important records of the Piedmont’s fire history.

“Big Bone Lick,” “Big Talk,” and “Flush”

“Big Bone Lick,” “Big Talk,” and “Flush” Robert Morgan (bio) Click for larger view View full resolution “. . . the Indians said the peaks were talking to each other in the idiom that mountains use. . .” Pilot Mountain, North Carolina, photographed by AnDrew McKenzie, 2003, courtesy of a GNU Free Documentation License. [End Page 116] Big Bone Lick At Big Bone Lick the first explorers found skeletons of elephants they said, found ribs of wooly mammoths, tusks. They dug out teeth the size of bricks and skulls of giant bison, beavers. In salty mud licked bare by elk and deer and buffalo and bears for ten millennia, the bones seemed wreckage from a mighty dream, a graveyard from a golden age, or killing ground of titans. Here they saw the ruins of a world survived by its diminutives, where Eden once gave way and shrank to just a regular promised land to fit our deadly, human scale. Big Talk When mountains boomed and boomed again returning echoes all along the chain, the Indians said the peaks were talking to each other in the idiom that mountains use across the mighty distances with giant syllables and rests. White hunters feared it might be guns or even cannon natives had somehow acquired to warn them from the better hunting grounds and streams, the blasts as loud as thunder on the clearest days and coldest nights. Geologists would later hold the groans and barks inside the ridge were shelves of massive, restless rock that slipped or dropped far down within the mountains’ guts, a fracture or a crashing at some fault as part [End Page 117] of the tectonic conversation among the continents as old as planet earth or starry birth, the mutter of creation’s work. Flush A common sight in graveyards in the countryside’s the sunken grave. Though times may vary in each case the average age for graves to cave is roughly half a century. To compensate old folks would curve the dirt in mounds above the site. But after several years the box below gives way and heavy earth subsides, to settle, crush the whole container of remains, the dust of the beloved, as clay unites with clay. And what is seen above in turf ’s a new depression near the stone, a pool of absence filled by rain or snow or blowing leaves until the spot is flush again, until the human is replaced, with hill and wind and planet’s curve. [End Page 118] Robert Morgan Robert Morgan is a poet, novelist, and biographer. His most recent book is Boone: A Biography (2007), winner of the Kentucky Literary Award and finalist for the Los Angeles Times Book Award. He is the recipient of fellowships and awards from the Guggenheim and Rockefeller Foundations, the National Endowment for the Arts, and the American Academy of Arts and Letters, as well as an honorary degree from his alma mater, the University of North Carolina at Chapel Hill. Since 1971 he has taught at Cornell University, where he is now Kappa Alpha Professor of English. Copyright © 2011 Center for the Study of the American South

Rural Cooperatives Magazine, July/August 2011

Features- Taking the plunge; Pilot mountain pride forges links between growers and buyers; Hogs on the range; Market edge for the wedge; Finding a way; Banking on butanol; Split decision

Upper Triassic (Norian) hypercalcified sponges from the Musandam Peninsula (United Arab Emirates and Oman)

Supercalcified sponges, including sphinctozoans, inozoans, chaetetids, spongiomorphids, occurring in Upper Triassic (Norian-Rhaetian) shallow-marine limestones of Musandam Mountains in United Arab Emirates (UAE), are described. The following taxa were determined: sphinctozoans: Hajarispongia osmani Senowbari-Daryan and Yancey, Nevadathalamia arabica n. sp., Nevadathalamia conica n. sp., Fanthalamia milahaensis n. sp., Iranothalamia incrustans (Boiko), Cinnabaria regularis n. sp.; inozoans: Cavsonella triassica n. sp., Molengraaffia regularis Vinassa de Regny, Peronidella? sp., Circopora cf. caucasica Moiseev, Circopora? sp.; spongiomorphids: Spongiomorpha sp.; chaetetids: Lovcenipora chaetetiformis Vinassa de Regny, Lovcenipora musandamensis n. sp., Lovcenipora sp., chaetetid sponge gen. et sp. indet. The most abundant sponge in the studied material is Nevadathalamia arabica n. sp. The described sponge association of the Arabian shelf (Musandam Mountains) shows close affinity to the sponge association known from age-equivalent terranes in the Panthalassa Ocean (Sonora Mountains in Mexico; Pilot Mountains in Nevada, USA), but is remarkably different from sponge associations in carbonates bordering the Tethys. This difference goes along with the biogeography of wallowaconchid bivalves and is most likely attributed to climatic, palaeogeographic or oceanographic factors.

Manual Traffic Allocation for Small-Town Networks

A new manual travel allocation spreadsheet for street networks in small towns is described. The method is useful for rural planning organizations or state departments of transportation that must cost-effectively develop transportation models for small towns that expect growth and new transportation facilities. Unlike the usual computerized network model, this spreadsheet combines available census data and maps with expert judgment to assign traffic volumes manually to small networks with up to 10 internal and 12 external zones. The spreadsheet produces origin-destination matrices for manual or computer-based assignment. A case study application in Pilot Mountain, North Carolina, demonstrates the method.

Ion microprobe age and geochemistry of southern appalachian basement, with implications for Proterozoic and Paleozoic reconstructions

Ion microprobe U–Pb analyses of zircons from basement units in the southern Appalachians, combined with supporting isotopic compositions and major and trace element geochemistry, have delineated a granitic magmatic pulse ∼1165–1150 Ma. The pulse is manifested by the Watauga River Gneiss (western Blue Ridge), Toxaway, Wiley, and Sutton Creek gneisses (eastern Blue Ridge), Pilot Mountain and Grassy Creek gneisses (Sauratown Mountains window), and possibly the Forbush gneiss (∼1140 Ma, Inner Piedmont or Sauratown Mountains window) and Cranberry-Mine Layered Gneiss (∼1190 Ma, western Blue Ridge). Additional samples analyzed include the Blowing Rock Gneiss (∼1080 Ma, Grandfather Mountain window), and the Carvers Gap Granulite Gneiss (∼1.8 Ga) and Cloudland Granulite Gneiss (detrital cores ∼1.2–1.8 Ga) from the Mars Hill terrane. Age data were evaluated by calculating concordia ages and concordia probability plots using 206 Pb*/ 238 U and 207 Pb*/ 206 Pb* data simultaneously. Rocks in the main magmatic pulse are granitic (63–72 wt.% SiO 2 ), but elevated in K and incompatible trace elements compared to typical subduction-related magmas, and initial Nd ratios cluster tightly near CHUR. Mars Hill terrane samples are distinct in age, geochemistry (poorer in K and incompatible elements), and isotopic compositions (ε Nd −7.6 and −5 at 1.0 Ga). Zircons from almost all samples have metamorphic rims that yield ages ∼1030 Ma, with the exception of the Blowing Rock Gneiss. Ages of Grenvillian magmatism and metamorphism are similar to reported ages from the northern Blue Ridge of Virginia, the Adirondack Highlands, the Central Metasedimentary Belt (Canadian Grenville Province), and the Llano uplift of Texas. This suggests the entire southeastern margin of Laurentia has a similar history ∼1.2–1.0 Ga. Although consistent with known ages in Laurentia, the presence of ∼1.8 Ga rocks and T DM ages commonly >1.6 Ga is inconsistent with the inferred 1.6 Ga margin of Laurentia. This suggests either that the 1.4–1.5 Ga mid-continent terrane separates older portions of Laurentia, that this region was exotic, or that it was a rifted fragment of Laurentia reattached during Grenville orogeny. Surprisingly few Paleozoic metamorphic zircon rims have been identified, but the few analyses obtained from samples in the eastern Blue Ridge yield late Acadian ages (∼350 Ma). The similarity of basement units across the southern Appalachians suggests a relationship between these provinces and that the Piedmont terrane is not exotic to Laurentia during the Appalachian orogenic cycle.

Two New Species of Viola (Violaceae) from the Intermountain West, U. S. A.

Viola lithion andV. franksmithii are rock-dwelling endemics that belong to the North American perennial, caulescent, simple-leaved, blue-, purple-, or white-flowered group of species.Viola lithion, from the White Pine and Pilot mountain ranges of eastern Nevada and adjacent Utah, belongs to sectionChamaemelanium subsectionCanadenses. It most closely resembles the reniform-leaved, Olympic MountainV. flettii, together with which it possibly shares an ancestry with the widespread and allopatricV. canadensis. Viola franksmithii, restricted to the Logan Canyon drainage of the Bear River Range in northern Utah, belongs to sectionRostellatae subsectionRosulantes. It comes closest morphologically toV. howellii of the Coast Range, but likely evolved from the widespreadV. adunca or a common ancestor.

Late Triassic thalamid sponges from Nevada

A study of Upper Triassic (Norian) thalamid sponges (“sphinctozoans”) from the Pilot Mountains, Garfield Hills, and East Range, Nevada, reveals an abundance of calcified sponges of the suborder Porata Seilacher. Two new species, Polycystocoelia silberlingi n. sp. and Neoguadalupia? norica n. sp., are added to our knowledge of five thalamid sponge taxa previously known from Nevada. All specimens have been neomorphically altered to calcite in a manner implying an original aragonite mineralogy.At the species level, the sponges show a restricted distribution. Nevadathalamia cylindrica (Seilacher) is a species also occurring in Sonora, Mexico, and previously known from the Yukon of Canada, but all other species are endemic to west-central and northwestern Nevada. At the generic level, similarities exist with species known from the Tethyan Realm, the Yukon, and south China. The genus Polycystocoelia has been known previously only from Hubei, China, and from the Yukon Territory, Canada. Neoguadalupia was previously known only from the Lower and Upper Permian of China. The occurrence of this genus in Nevada constitutes the first record of the genus outside of the Permian System of China.

Paleotectonic significance of the quartzite of the Sauratown Mountains window, North Carolina

Research Article| October 01, 1989 Paleotectonic significance of the quartzite of the Sauratown Mountains window, North Carolina Dan Walker; Dan Walker 1Department of Geological Sciences, University of Tennessee, Knoxville, Tennessee 37996-1410 Search for other works by this author on: GSW Google Scholar Steven G. Driese; Steven G. Driese 1Department of Geological Sciences, University of Tennessee, Knoxville, Tennessee 37996-1410 Search for other works by this author on: GSW Google Scholar Robert D. Hatcher, Jr. Robert D. Hatcher, Jr. 1Department of Geological Sciences, University of Tennessee, Knoxville, Tennessee 37996-14102Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 Search for other works by this author on: GSW Google Scholar Author and Article Information Dan Walker 1Department of Geological Sciences, University of Tennessee, Knoxville, Tennessee 37996-1410 Steven G. Driese 1Department of Geological Sciences, University of Tennessee, Knoxville, Tennessee 37996-1410 Robert D. Hatcher, Jr. 1Department of Geological Sciences, University of Tennessee, Knoxville, Tennessee 37996-14102Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1989) 17 (10): 913–917. https://doi.org/10.1130/0091-7613(1989)017<0913:PSOTQO>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Dan Walker, Steven G. Driese, Robert D. Hatcher; Paleotectonic significance of the quartzite of the Sauratown Mountains window, North Carolina. Geology 1989;; 17 (10): 913–917. doi: https://doi.org/10.1130/0091-7613(1989)017<0913:PSOTQO>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Recent mapping within the metamorphic core of the southern Appalachians has led to the identification of several internal basement massifs interpreted to be windows that expose parautochthonous basement beneath the main thrust sheet. One such internal massif is exposed within the Inner Piedmont of North Carolina by the Sauratown Mountain window and is overlain by a cover sequence of arkose, schist, and quartzite. Detailed examination of the primary cross-stratification types preserved within the quartzite at Pilot Mountain indicates that deposition took place in several marine environments ranging from foreshore to inner shelf. Deposits of similar origin within the Early Cambrian North American passive-margin sediments appear to thin west to east, from 80 m at the Chilhowee Group type locality at Chilhowee Mountain (300 km west-southwest of Pilot Mountain) to 40 m within the Unaka belt (150 km west of Pilot Mountain). The quartzite at Pilot Mountain is more than 45 m thick and therefore does not appear to represent a distal part of this passive-margin sequence. Alternatively, two paleotectonic interpretations seem plausible: (1) quartzites of the Sauratown Mountains window, North Carolina, represent Late Proterozoic (Tallulah Falls-Ashe Formation equivalent) deposition along a sea-floor high associated with the rifted basement terrane during the rift phase prior to the opening of Iapetus; or (2) quartzites of the Sauratown Mountains window, North Carolina, represent latest Proterozoic to Early Cambrian (Chilhowee Group time equivalent) deposition on an isolated, rifted continental fragment during the drift phase of the North American-Iapetus margin evolution. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Laterally Discontinuous Porous Zones in Subsurface Mississippian Monteagle Limestone (Oolitic), Northeastern Tennessee--How Were They Formed?: ABSTRACT

Examination of over 500 logs composed of gamma-ray, bulk-density, and porosity graphs that penetrated the Mississippian platform carbonate unit known as the Monteagle Limestone (oolitic) in the subsurface of Morgan County, Tennessee (Twin Bridges and Pilot Mountain Quadrangles), enabled recognition of laterally discontinuous porous zones that formed at eight different stratigraphic levels within the Monteagle. Seven panel diagrams per quadrangle (a total of 14 panels) were prepared to ascertain the three-dimensional geometry, facies relationships, and distribution of porous zones of subsurface stratigraphic units in the Mississippian System. These panels may be considered as substitutes for seismic traverses.

An oxygen isotope and geochemical study of meteoric-hydrothermal systems at Pilot Mountain and selected other localities, Carolina slate belt

Several epigenetic mineral deposits in the Ca1rolina slate belt are intimately related to meteoric-hydrothermal systems of late Precambrian and early Paleozoic age. At Pilot Mountain, low 18 O rocks correlate well with zones of strong silicic alteration and alkali leaching accompanied by high alumina minerals (sericite, pyrophyllite, andalusite + or - topaz) and anomalous concentrations of Cu, Mo, Sn, B, and Au. The alteration occurs within andesitic volcanic and volcaniclastic rocks and is associated with a subvolcanic(?) dacite porphyry stock on the southeastern slope of the mountain. Tilting and erosion have exposed an oblique section through the original system, interpreted to expose shallower rocks to the northwest. A 4-km 2 central zone of slight 18 O depletion (delta 18 O (sub whole rock) = 4.3-6.1ppm) occurs on the broad and resistant (silicifled) western flank of Pilot Mountain, predominantly within quartz-sericite schist and quartz granofels containing pods of high A1 minerals. A magmatic source for much of the sulfur and metal is likely, and a subordinate magmatic water component in the fluid of the central zone is possible. This central zone is surrounded by a >30-km 2 peripheral zone of low 18 O sericite schists, chlorite-sericite schists, and andesitic volcanic rocks (delta 18 O (sub whole rock) < 3.8ppm), with the lowest values (1.4ppm) occurring in intensely sericitized rocks on the eastern flank of Pilot Mountain, near the apex of the dacite porphyry stock. Rhyolites of the Uwharrie Formation (delta 18 O = 3.8-6.3ppm) are not as strongly altered as nearby andesites and may postdate the hydrothermal alteration. The fluid calculated to be in equilibrium with the lowest 18 O quartz veins and country rocks at 300 degrees + or - 50 degrees C would have delta 18 O approximately -4.5 + or - 2.0 per mil, whereas analyses of radiating pyrophyllite indicate equilibrium with a fluid having delta D approximately -30 per mil, consistent with a slightly 18 O-shifted, low-latitude meteoric water. Subsequent greenschist metamorphism caused intermineral isotopic reequilibration in several samples and may have modified preexisting alteration assemblages, but it did not destroy the large delta 18 O anomaly produced by meteoric-hydrothermal activity at Pilot Mountain. Reconnaissance studies of other alteration zones in the Carolina slate belt have so far disclosed the involvement of meteoric-hydrothermal fluids at the Snow Camp pyrophyllite deposit, at the Hoover Hill and Sawyer Au mines, and probably at the Haile and Brewer Au mines.

Remote detection of metal anomalies on Pilot Mountain, Randolph County, North Carolina; reply

Remote detection of metal anomalies on Pilot Mountain, Randolph County, North Carolina; reply

Remote detection of metal anomalies on Pilot Mountain, Randolph County, North Carolina; discussion

Remote detection of metal anomalies on Pilot Mountain, Randolph County, North Carolina; discussion

Recent earthquake activity in the Snowy Moutains region and its relationship to major faults

Abstract The seismicity of the Snowy Mountains region, which is situated between 36° to 37°S and 148° to 149°E, was studied for the period June 1971 to February 1982. Most earthquake epicentres seem to correspond to major faults. The 1971 Middlingbank earthquakes, on the other hand, were located in a region where no major faults have been mapped. Focal mechanisms could be determined for three earthquakes: the 1981 Suggan Buggan earthquake, which was probably associated with the Moyangul River Fault and was of strike‐slip type; the nearby earthquake beneath the Pilot mountain, which occurred in 1976 and was a thrust‐faulting event; and the 1971 Middlingbank earthquake series that took place a few kilometres south of Lake Eucumbene and was associated with right‐lateral strike‐slip faulting along an east trending plane. Although these earthquakes were associated with different types of faulting, they were all probably caused by horizontal compressive stresses in the crust acting along an azimuth of about 120°, thus confirming previous investigations of crustal stresses made in southeastern Australia. The 1971 Middlingbank earthquakes may have been associated with the filling of Lake Eucumbene, because the maximum water level up to that time was reached in December 1970. However, the influence of the reservoir cannot be properly assessed.

Remote detection of metal anomalies on Pilot Mountain, Randolph County, North Carolina

Pilot Mountain, a hydrothermally altered monadnock within the Carolina slate belt, contains areas of anomalously high amounts of Cu, Mo, and Sn in the soils. Leaves of canopy trees in the mineralized zone also contain more copper than trees in a nearby control area. Spectral data were processed using a wave-form analysis technique to minimize background noise caused by canopy variations and slope effects. Areas of spectral changes in the chlorophyll absorption region seem to correlate well with areas containing anomalous metals.--Modified journal abstract.

Development of bedding-normal boudins in the Pilot Mountains, Nevada

Boudins with long axes (BA) oriented subnormal to bedding and to associated fold axes are observed in folded rocks in a thrust sheet exposed near the base of a regionally extensive allochthon in west-central Nevada, USA. Formation of the boudins is related to development of a regional fold-set coeval with major thrusting. The axes of boudins lie at a high angle to bedding, and in some instances, boudins define tight to isoclinal folds which are geometrically associated with the regional deformation. Quartz c-axis fabrics from oriented thin-sections of the boudins indicate extension parallel to the boudin axes (BA). These relations and other mesoscopic structural data indicate a complex deformational history for boudin development. The history involves thin layers (to become boudins) deformed in folds disharmonic to major structures within the thrust sheet followed by flattening and associated extension parallel to fold axes. During flattening, arcuation occurred within the deforming mass resulting in rotation of fold axes and boudin axes (BA) toward the axis of finite extension ( X). Extension parallel to BA recorded in the petrofabrics of boudins records incremental strain axes oriented at a high angle (50°) to the finite X and is probably related to an early plane-strain state associated with disharmonic folding. The finite extension ( X) is down-dip in axial planes of major folds formed during thrusting and indicates a northwest to southeast transport for the thrusts.

Supplementary Data for: Structure and Stratigraphy of the Luning Allochthon and the Kinematics of Allochthon Emplacement, Pilot Mountains, West-Central Nevada

Synthetic Fabric Models To aid discussion of the geometry of folds forward models are constructed to illustrate and test the inferred sequential development of folds in three thrust sheets, nappe N1 (eastern domain) and imbricates n 1c and n 2c (western domain). Models consist of equal-area projections of the geometries of folds of bedding and, where applicable, folds of axial surfaces. Fold axes are represented as dots with numerical subscripts indicating their respective fold sets (n = 1,2,3). Orientations of fold surfaces represented in models are those which yield good approximations to the surface orientations measured around the curvature of folds characteristic of particular fold sets. The distribution of fold surface orientations is effectively weighted by selection of surfaces to be used in subsequent stages of modeled fold development. Selection of particular fold surface orientations is made on the basis of fold style and the dominant attitude of fold surfaces which define folds of a particular fold set. As an example, a tight fold with long homoclinal limbs would, during modeled refolding of bedding, be represented primarily by the orientations of the fold limbs. Napple N2 (Eastern Domain). Synthetic fabric diagrams constructed from a forward model of the geometry of sequential folding for nappe N2 are compared to the observed fabric in Figure 10. First folds are modeled as a tight fold set with a shallowly plunging, northeasterly-trending fold axis lying in an axial plane with an orientation of N35°E 60°NW. Elements of the first folds are refolded by second-phase folds which have northwesterly striking, near-vertical axial planes. Orientations of modeled P 2 fold axes are variable and dependent on the initial attitude of P 1 fold elements.

Kinematics of late Mesozoic thrusting, Pilot Mountains, west-central Nevada, U.S.A.

The northern Pilot Mountains of west-central Nevada, consist of a complexly deformed terrane of imbricate thrust nappes composed of rocks of Permian(?), Triassic through Jurassic, and possible Cretaceous ages. Three episodes of fold and thrust generation are recognized on the basis of folded thrusts and thrusted folds, and deformation and emplacement of the nappes is constrained as having occurred during the late Mesozoic. Folds are apparently coeval with thrust faults, and fold geometry is used in determining approximate directions of thrust displacement. The history of thrust displacement is complex and involves three directions of motion on a regionally extensive detachment surface, the Luning thrust. The first motion, from NW to SE, results in displacements of the order of several tens of kilometres and is the probable result of NW-SE regional compression. The final two episodes of motion are NE-SW followed by E-W; they result in small displacements and are possibly the product of gravity sliding of the thrust sheet into depressions in the autochthon. Sites of downwarp in the autochthon may have been formed either by load induced subsidence or regional compression.

Structure and stratigraphy of the Luning allochthon and the kinematics of allochthon emplacement, Pilot Mountains, west-central Nevada

The northern Pilot Mountains of west-central Nevada consist of a complexly deformed terrane of imbricate thrust sheets composed of rocks of Mesozoic and possible late Paleozoic ages. Thrust nappes within the allochthonous terrane, named the Luning allochthon, are principally constituted by the Upper Triassic Luning Formation. Locally, the nappes contain numerous imbricate thrust slices, some of which are composed of undifferentiated Sunrise-Gabbs Formation (Triassic and Jurassic) and unnamed volcanic-carbonate assemblages of probable Permian or Triassic age. Three episodes of folding and thrusting are recognized on the basis of folded thrusts and thrusted folds, and deformation and emplacement of the allochthon is constrained as late Mesozoic. Folds apparently formed coevally with thrust faults and fold geometry is used to determine approximate directions of thrust transport. Thrust displacements are responsible for 35 to 40 km of an estimated 70 km of intra-allochthon contraction which is inferred from lithofacies analysis of rocks juxtaposed by thrust nappes and from the structural overlap of imbricate thrusts. The history of thrust displacement is complex and involves three directions of motion on a regionally extensive detachment surface, the Luning thrust. First motion, from northwest to southeast, resulted in the major component of stratal contraction and is the probable result of northwest-southeast regional compression. The final two episodes of motion are northeast to southwest followed by east to west; they resulted in small displacements and are possibly the product of gravity sliding of the thrust sheets into a depression formed beneath part of the allochthon within the autochthon. The site of downwarp in the autochthon may have formed by either load-induced subsidence or regional compression.