A gravity survey of part of the Long Valley district, Idaho

Kinoshita, W.T.

doi:10.3133/ofr6273

Cited by 8 publications

(5 citation statements)

References 3 publications

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“…At least 2,300 m of valley-fill sediments are found in Long Valley between the West Mountains escarpment on the Long Valley fault and the town of Donnelly (southeastern pl. 1; Kinoshita, 1962;Schmidt and Mackin, 1970). These are composite deposits that began to form in the late Tertiary because of drainage disruption during basalt eruption (see previous discussion on Idaho Group, QTi) but resulted mostly from glacial activity during the Pleistocene.…”

Section: Quaternary Depositsmentioning

confidence: 99%

Geology of the Payette National Forest and vicinity, west-central Idaho

Lund¹

2021

Professional Paper

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Before the Late Cretaceous, the eastern and western parts of the geologically complex Payette National Forest, as divided by the Salmon River suture, had fundamentally different geologic histories. The eastern part is underlain by Mesoproterozoic to Cambrian(?) rocks of the Laurentian (Precambrian North American) continent. Thick Mesoproterozoic units, which are at least in part equivalent in age to the Belt Supergroup of northern Idaho and western Montana, underwent Mesoproterozoic metamorphic and deformational events, including intrusion of Mesoproterozoic plutons. During the Neoproterozoic to early Paleozoic, the western edge of Laurentia was rifted. This event included magmatism and resulted in deposition of rift-related Neoproterozoic to Lower Cambrian(?) volcanic and sedimentary rocks above Mesoproterozoic rocks. The western part of the forest is underlain by upper Paleozoic to lower Mesozoic island-arc volcanic and sedimentary rocks. These rocks comprise four recognized island-arc terranes that were amalgamated and intruded by intermediate-composition plutons, probably in the Late Jurassic and Early Cretaceous, and then sutured to Laurentia along the Salmon River suture in the Late Cretaceous.The Salmon River suture formed as a right-lateral, transpressive fault. The metamorphic grade and structural complexity of the rocks increase toward the suture from both sides, and geochemical signatures in crosscutting plutonic rocks abruptly differ across the crustal boundary. Having been reactivated by younger structures, the Salmon River suture forms a north-trending topographic depression along Long Valley, through McCall, to the Goose Creek and French Creek drainages.During the last stages of metamorphism and deformation related to the suture event, voluminous plutons of the Idaho batholith were intruded east of the suture. An older plutonic series is intermediate in composition and preserved as elongated and deformed bodies near the suture and as parts of roof pendants to younger intrusions to the east. A younger magma series consists of undeformed, marginally peraluminous plutons that formed east of the suture after accretion.After suture-related compression, crustal extension resulted in voluminous volcanic and plutonic rocks of the Eocene Challis magmatic complex on the east side of the forest. Extension, from the Late Cretaceous to post-Miocene, uplifted the area of By Karen Lund the Idaho batholith relative to the western part of the forest and formed dominant highlands along the Snake River. Extensional basins also formed such that, in the Miocene, the Columbia River Basalt Group and related basaltic lavas flowed over most of the lower elevations on the western side of the forest and redirected erosional debris into north-trending, fault-controlled drainages and young sedimentary basins. Figure A1. Geographic extent of Payette (PNF) and Salmon (SNF) National Forests, west-central Idaho.

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Section: Quaternary Depositsmentioning

confidence: 99%

Geology of the Payette National Forest and vicinity, west-central Idaho

Lund¹

2021

Professional Paper

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“…Obviously, fault-bounded basins may contain large volumes of deformed fill. The gravity survey of Kinoshita (1962) suggests that basin fill is a minimum of 600 m thick in the part of the Long Valley described here.…”

Section: Idaho Fluvial Placersmentioning

confidence: 65%

Titanium mineral resources of the western U.S.: An update

Force¹,

Creely²

2000

Open-File Report

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Thirteen deposits or districts in the western U.S. have been examined in which titaniummineral resources have been reported or implied. These deposits are of the following general types (in probable order of importance): 1) Cretaceous shoreline placer deposits, 2) silica-sand deposits of California, 3) fluvial monazite placers of Idaho, 4) anorthositerelated deposits, and 5) clay and bauxite deposits of the northwestern U.S. Relative to previous reports, this one shows some greater and some lesser resources (table 1). In any case, titanium-mineral resources of the western U.S. (west of 103 o longitude) remain modest at world scale except as unconventional (especially perovskite) and by-product (especially porphyry) resources. Some deposits, however, have enhanced value to the titanium explorationist for the geologic relations they illustrate. Among the new conclusions are: a) Loci of Cretaceous shoreline placers form linear patterns, nested as a function of age, that can be traced for thousands of kilometers, permitting focused exploration in whole new mountain ranges. b) Medial hematite-ilmenite solid-solution, which is highly magnetic, is a major carrier of TiO 2 values in the Cretaceous deposits of Wyoming. This phase was previously thought to be relatively rare. c) Regressive shoreline placer deposits in indurated Cretaceous sequences expose intricate facies relations, such as the construction of shoreface sequences by long-shore drift over tidal-channel fill, without much loss of paleogeographic information. d) Due to deep weathering, virtually every Eocene sediment that accumulated in the Ione basin at the foot of the Sierra Nevada has economic value, permitting recovery of altered ilmenite and zircon along with silica, clay, coal, and gold. Ilmenite is most abundant in newly recognized shoreline sands. e) Upper Tertiary fluvial placers of Idaho formed in and filled fault-bounded basins and thus are far more voluminous than deposits in the modern valley system. Previously reported resources are thus far too low. f) Mafic igneous rocks of Proterozoic age near Bagdad, Arizona are of ophiolitic affinity, but contain nelsonitic ilmenite enrichments associated with anorthositic layers.

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“…He interprets the large gravity anomalies in terms of density contrasts extending to depths of the order of 16 km. Kinoshita [1962] and Davis and Kinoshita (private communication, 1964) The value of gravity measurements for study ing local geological structures has long been recognized, and, as the publications summarized here indicate, the U. S. Geological Survey is actively involved with this application of the gravity method. In addition, gravity methods are being used to support seismic refraction studies of crustal structure recently initiated by the Geological Survey [Pakiser } 1963].…”

Section: S Geological Survey Hawaiian Volcano Observatory Hawaiimentioning

confidence: 99%

The U. S. Geological Survey's Gravity program in Washington, Idaho, Montana, and Wyoming

Hill

1965

Eos Trans. AGU

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The following summary of the U. S. Geological Survey gravity program in Washington, Idaho, Montana, and Wyoming is one of a series of short papers that outline Geological Survey gravity projects in the western United States. The substance of this summary is a list of references of published papers on U. S. Geological Survey gravity projects in the northwestern states together with an index map (Figure 1) showing the location of the project, the approximate a real coverage reported in the publication, and the contour map given in the publication. Areas in Figure 1 are related to the References (part 2) by a number code. In addition, the gravity projects in progress are listed in Table 1, indicating the area in which the work is being done and the person in charge of the project. Capital letter relate the locations of the projects in Figure 1 to the list of projects in Table 1. No attempt has been made to indicate the areal coverage or contour interval of the projects in progress.

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A gravity survey of part of the Long Valley district, Idaho

Cited by 8 publications

References 3 publications

Geology of the Payette National Forest and vicinity, west-central Idaho

Geology of the Payette National Forest and vicinity, west-central Idaho

Titanium mineral resources of the western U.S.: An update

The U. S. Geological Survey's Gravity program in Washington, Idaho, Montana, and Wyoming

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