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Charles Sandberg

Publications and source records attributed to Charles Sandberg.

30 records · Page 2Linked to original sources
USGS1999

A late Frasnian (Late Devonian) radiolarian, sponge spicule, and conodont fauna from the Slaven Chert, northern Shoshone Range, Roberts Mountains allochthon, Nevada

Co-occuring conodonts, radiolarians, and sponge spicules from the type locality of the Slaven Chert, northern Shoshone Range, Nevada, indicate that the radiolarian and sponge spicule assemblage described herein correlates with the Late rhenana conodont Zone (late Frasnian). The moderately well preserved radiolarians are the first Frasnian-age fauna described from the Western Hemisphere. They include spumellarians, Ceratoikiscum, and Paleoscenidium, and a radiolarian which we have assigned to a new genus, Durahelenifore Boundy-Sanders and Murchey, with its type species, Durahelenifore robustum Boundy-Sanders and Murchey. Sponge spicules include umbellate microscleres of the Subclass Amphidiscophora, Order Hemidiscosa, previously documented only in Pennsylvanian and younger rocks.

Nevada↗
USGS1996

Alamo megabreccia: Record of a late devonian impact in southern Nevada

The Alamo breccia is probably the most voluminous known outcropping carbonate megabreccia. It occupies ~4000 km2 across 11 mountain ranges in southern Nevada, has an average thickness of ~70 m, and contains a volume of 250+ km3. The breccia is a single bed, of early Frasnian (early Late Devonian) age, that formed in the wake of a giant slide that deposited a lower chaotic debrite, containing clasts as large as 80 × 500 m, and an upper exquisitely graded turbidite. It is anomalously intercalated with cyclic shallow-water platform carbonates of the Guilmette Formation. The Alamo breccia is interpreted as a product of the Alamo event, a nearby marine impact of an extraterrestrial object, whereby impact-generated crustal shock waves and/or marine superwaves detached the upper ~60 m of platform along a horizontal surface. Loosened bedrock slid seaward across the platform, and some of it accumulated as the lower debrite. Rock-water exchange induced landward-propagated tsunami(s), whose uprush and/or backwash deposited the upper turbidite, partly above sea level. Evidence for impact includes shockedquartz grains, an iridium anomaly, and reworked conodonts, all found only within the breccia. Because the Alamo breccia is not known outside of Nevada, and because the early Frasnian time of the Alamo event is not noted for accelerated extinctions, being ~3 m.y. before the Frasnian-Famennian impact(s) and biotic crisis, the impact was probably only of moderate size.

Nevada↗
USGS1995

Reflexions on Frasnian and Famennian stage boundary decisions as a guide to future deliberations

The pros and cons of the three conodont-based boundaries of the Frasnian and Famennian Stages and their corresponding GSSPs (Global Stratotype Section and Point) are evaluated in terms of current taxonomic, biostratigraphic, and sedimentologic knowledge. Two of these boundaries are based on easily identified pelagic species, which provide excellent bases for global correlation. The third, for the base of the Frasnian, is based on a neritic species, whose taxonomy has been heatedly debated. The GSSPs for these three levels are all located in the Montagne Noire of southern France, partly because of political motivation to balance GSSPs selected in other regions. All three GSSPs are at levels from which global correlations cannot be effectively accomplished without aid from other, more complete sections or without making correlations strictly on the basis of taxonomic concepts - i.e., the entry of the definitive conodont species. Future deliberating bodies may want to reconsider the species chosen to delimit the base of the Frasnian and to select better GSSPs for all three boundaries.

Newsletters on Stratigraphy↗
USGS1991

Upper Devonian biostratigraphy of Michigan Basin

The Late Devonian Michigan Basin was floored by the Middle and Upper Devonian Squaw Bay Limestone, which was deposited during the downwarping that produced the basin within a former Middle Devonian carbonate platform. The Squaw Bay comprises three beds, each having a different conodont fauna. The two upper beds, deposited during the transitans Zone, have different conodont biofacies that reflect this deepening. The basin was largely filled by the deep-water, anaerobic to dysaerobic, organic-rich, black Antrim Shale, which has a facies relationship with the prodeltaic, greenish gray Ellsworth Shale that prograded into the basin from the west. The Upper Devonian (Frasnian to Famennian) Antrim Shale is divided into four members, from base to top: the Norwood, Paxton, Lachine, and upper members. These members are more or less precisely dated by conodonts. The Norwood was deposited during the transitans Zone to Ancyrognathus triangularis Zone, and the Paxton was deposited from that zone probably through the linguiformis Zone at the end of the Frasnian. The overlying Lachine was deposited during the early Famennian and has yielded faunas of the Upper crepida and Lower rhomboidea Zones. Only the lower part of the upper member is exposed, and near Norwood, Michigan, it yielded conodonts of the Lower marginifera Zone. The widespread Famennian floating plant Protosalvinia (Foerstia) has not yet been found in outcrops of the Antrim, and should not be expected to occur except in the upper member or highest part of the Lachine Member. Its range in terms of conodont zones is from the Upper trachytera Zone through the Lower expansa Zone and possibly into the Middle expansa Zone. One known subsurface occurrence might be datable as rhomboidea or Lower marginifera Zone, depending on gamma ray correlations to outcrops. Black shale deposition ended when the Late Devonian mud delta of the Bedford Shale prograded across the Michigan Basin from the east and then retreated as the regressive Berea Sandstone was being deposited during the major eustatic sea-level fall that ended the Devonian. The Bedford was deposited during the Upper expansa to Lower praesulcata Zones, and the Berea was deposited during the Middle to Upper praesulcata Zones. Both formations contain the spore Retispora lepidophyta, which is a global indicator of latest Devonian age.

Michigan↗
USGS1991

Late Devonian history of Michigan basin

The Upper Devonian sequence in the Michigan Basin is a westward extension of coeval cyclical facies of the Catskill deltaic complex in the Appalachian basin. Both basins and the intervening Findlay arch express the tectonic and sedimentational effects of foreland compression and isostatic compensation produced by the Acadian orogeny. The Late Devonian Michigan Basin formed as one of several local deeps within the long Eastern Interior seaway that separated the North American craton, backboned by the Transcontinental arch, on the west from the Old Red continent, Avalon terrane (microplate), and possibly northwest Africa on the east. Basin development began in the late Middle Devonian (late Givetian varcus Zone) with subsidence of a shallow-water carbonate platform formed by rocks of the Traverse Group. Subsidence was contemporaneous with Taghanic onlap of the North American craton. During subsidence, a thin transitional sequence of increasingly deeper water limestones separated by hardgrounds was deposited in the incipient Michigan Basin during the latest Givetian to earliest Frasnian disparilis to falsiovalis Zones. Deposition of this sequence culminated during the early Frasnian transitans Zone with a calcareous mudstone bed at the top of the Squaw Bay Limestone. Subsidence was followed by a 12-m.y.-long Late Devonian episode of slow, hemipelagic, basinal sedimentation of organic black muds that formed the Antrim Shale, interrupted basinwide only by deposition of its prodeltaic Paxton Member. Westward, the basinal Antrim black muds intertongued with greenish gray, deltaic and prodeltaic muds of an eastward-prograding delta platform formed by the Ellsworth Shale. Basinal black shale deposition ceased in latest Devonian (late Famennian Lower praesulcata Zone) time, when the Bedford deltaic complex prograded westward, completely filling the Antrim Basin and even covering part of the older Ellsworth deltaic complex on the west. As sea level was lowered eustatically near the end of the Devonian, the regressive Berea Sandstone terminated deltaic deposition. After an Early Mississippian erosional episode, widespread deposition of the unconformably overlying Lower Mississippian Sunbury Shale began during the next transgression, associated with a major eustatic rise in the Lower crenulata Zone.

Michigan↗
USGS1985

Devonian eustatic fluctuations in Euramerica

The Devonian System of Euramerica contains at least 14 transgressive-regressive (T-R) cycles of eustatic origin. These are separated into three groups (or depophases) and from Carboniferous cycles by three prominent regressions. Twelve post-Lochkovian T-R cycles are recognized, and they commonly appear to result from abrupt deepening events followed by prolonged upward shallowing. Deepening events in the western United States (especially Nevada), western Canada, New York, Belgium, and Germany have been dated in the standard conodont zonation and are demonstrably simultaneous in several or all five regions. This synchroneity indicates control by eustatic sea-level fluctuations rather than by local or regional epeirogeny. Facies shifts in shelf sedimentary successions are more reliable indicators of the timing of sea-level fluctuations than are strandline shifts in the cratonic interior, because the latter are more influenced by local epeirogeny. Strandline shifts are most useful in estimating the relative magnitude for sea-level fluctuations. Devonian facies progressions and the three prominent regressions are of a duration and an order of magnitude that could have been caused by episodes of growth and decay of Devonian oceanic ridge systems. The described T-R cycles could have formed in response to mid-plate thermal uplift and submarine volcanism. The latter process may have been a control on small-scale (1–5 m thick), upward-shallowing cycles within the major T-R cycles. Continental glaciation could have been a factor in sea-level fluctuations only in the Famennian and could not have been responsible for the Devonian facies progressions or the numerous T-R cycles. The Frasnian extinctions were apparently cumulative rather than due to a single calamity. Two rapid sea-level rises occurred just before, and one at, the Frasnian-Famennian boundary. It is probable that this series of deepening events reduced the size of shallow-shelf habitats, caused repeated anoxic conditions in basinal areas, and drowned the reef ecosystems that had sustained the immensely diverse Devonian benthos.

GSA Bulletin↗
USGS1984

Late Devonian icriodontid biofacies models and alternate shallow-water conodont zonation

Recognition of differences in the habitats, apparatuses, and ranges of Late Devonian Icriodus and Pelekysgnathus permits refinement of their biofacies interpretations and construction of an alternate icriodontid zonation. Icriodus is a euphotic genus that predominated in most environments during the early Late Devonian (Frasnian) but died out during the early Famennian. Its apparatus consists of platform (I) elements; four larger, acodiniform cones; and two smaller, oneotodiform, scolopodiform, or drepanodiform cones. Pelekysgnathus is a shallow-water genus, which shortly after Icriodus died out, produced somewhat deeper water taxa with triple-rowed I elements that are homeomorphs of Icriodus I elements. Apparatuses for both single-rowed taxa ( Pelekysgnathus ) and triple-rowed taxa ( “Icriodus”) contain oistodiform cones, apparently in place of one or more of the acodiniform cones. Biofacies models for southern Belgium and Utah show that Icriodus lived not only in nearshore environments but ranged into the pelagic palmatolepid-bispathodid (I) and palmatolepid-polygnathid (II) biofacies. Younger “Icriodus”, however, inhabited mainly the deeper subtidal polygnathid-“icriodid” (III) and polygnathid-pelekysgnathid (IV) biofacies. Pelekysgnathus inhabited mainly the polygnathid-pelekysgnathid biofacies and ranged shoreward into the shallow-subtidal clydagnathid (V), scaphignathid (VI), patrognathid (VII), and pandorinellinid (VIII) biofacies, but has not yet been found in the hypersaline antognathid (IX) biofacies (new). The Late Devonian, subdivided by 28 mainly Palmatolepis -based zones from the Lower (Polygnathus) asymmetricus to Upper (Siphonodella) praesulcata Zones in the standard conodont zonation for pelagic biofacies, can be subdivided into nine icriodontid-based zones in nearshore biofacies. In ascending order, these are the Icriodus symmetricus; Lower and Upper Pelekysgnathus planus; Lower, Middle, and Upper “ I .” cornutus ; and Lower, Middle, and Upper “ I .” costatus Zones. Taxonomic revisions involve mainly relegating several previously described species to subspecies and morphotypes and raising some subspecies to species. Two new biostratigraphically significant subspecies, I. iowaensis ancylus n. subsp. and I. alternatus helmsi n. subsp., are recognized to occur both in the western United States and in Europe. Pelekysgnathus brevis n. sp. is described as new on the basis of a Middle Devonian occurrence in Utah.

Arizona, Colorado, Idaho, New Mexico, Nevada, Utah↗
USGS1976

Revision of Mississippian stratigraphy, eastern Idaho and northeastern Utah

New paleontologic evidence requires a revision of previous interpretations of the stratigraphy of Mississippian sequences in the Cordilleran miogeosyncline of eastern Idaho and northeastern Utah. A postulated unconformity between rocks of early Osagean age and rocks of middle Meramecian age is no longer tenable in the light of new data. The new evidence supports continuous deposition from the Lodgepole Limestone (Kinderhookian and early Osagean age) into the Little Flat Formation (early Osagean to middle Meramecian age) and its equivalents, and the interpretation of a phosphatic siltstone and shale interval in the lower part of the Little Flat Formation as a starved-basin facies.

Idaho, Utah↗
USGS1975

Silurian and Devonian miogeosynclinal and transitional rocks of the Fish Creek Reservoir window, central Idaho

Documentation of Devonian continental-shelf shallow-water carbonate rocks in the core of the Fish Creek Reservoir window shifts the known westernmost limit of the Devonian miogeosyncline 50 km (30 mi) southwest across the structural grain from the well-known miogeosynclinal sequence in the Lost River Range. The miogeosynclinal carbonate sequence in the window has a minimum thickness of 450 m (1,500 ft). It comprises the upper Lower Devonian (Emsian) and lower Middle Devonian (Eifelian) Carey Dolomite (new), the upper Middle Devonian (Givetian) and Upper Devonian Jefferson Formation, and the Upper Devonian Picabo Formation (new). Conodont faunas precisely date the Carey. The Picabo Formation, composed of interbedded sandy dolomite-pebble conglomerate and dolomitic quartzose sandstone, is unlike any previously described formation of Late Devonian or Early Mississippian age in central Idaho. It resembles parts of the Stansbury, Beirdneau, Leatham, and Victoria Formations, which reflect areas of local Late Devonian uplift and erosion of older shelf rocks in northern Utah and southeastern Idaho. Transitional (continental-slope) rocks of the Roberts Mountains Formation representing reef and offreef facies are thrust over the Devonian shelf sequence within the Fish Creek Reservoir window. The Roberts Mountains Formation here is precisely dated as latest Silurian (Pridolian, eosteinhornensis Zone) through earliest Devonian (Lochkovian) by a sequence of conodont faunas. The easternmost known exposures of possible Devonian siliceous facies rocks assigned to the Milligen(?) Formation are present less than 4.8 km (3 mi) southwest of the shelf sequence. Structural relations and paleotectonic reconstructions suggest that they have a minimum eastward translation of 32 km (20 mi). The Devonian continent-ocean basin interface, along which the Antler orogenic belt developed at this latitude, probably was located near the east edge of the present Idaho batholith.

Idaho↗
USGS1975

Stratigraphy, conodont dating, and paleotectonic interpretation of the type Milligen Formation (Devonian), Wood River area, Idaho

The Milligen Formation at and near its type locality in the Wood River area is considerably older than and unrelated to rocks of Early Mississippian age called Milligen Formation in the Lost River Range and other ranges of east-central Idaho. Conodont faunas were found in limestones of a thin upper member of the sparsely fossiliferous marine Milligen Formation in its principal reference section at Milligen Gulch, at Fisher Canyon, and near Bellevue, Idaho. The faunas include indigenous conodonts here assigned to the early Late Devonian (early Frasnian) Lower and Middle Polygnathus asymmetricus Zones, and reworked conodonts derived from several Middle and Early Devonian conodont zones. An underlying much thicker argillite member of the Milligen contains fewer limestones, but a thin encrinite interbed near the middle of the member yielded early Middle Devonian (Eifelian) conodonts. This lower member probably represents most of Middle and Early Devonian time. Although its base is nowhere exposed in the Wood River area, the Milligen is inferred to have been deposited on the Silurian Trail Creek Formation, which crops out just to the east in the Pioneer Mountains. The age of the Milligen is therefore wholly Devonian and the highest fossiliferous beds are no younger than early Late Devonian. Reworked Middle and Early Devonian conodonts in limestone turbidites of the upper member of the Milligen Formation are identical to conodonts found in shelf (miogeosynclinal) carbonate rocks farther east. A postulated eastern source for the turbidites is supported by new data on the distribution, thickness, and tectonic facies of Devonian rocks that suggest the presence of a Late Devonian ridge on the continental shelf east of the Milligen depositional area. The Milligen Formation was intensely folded and was emergent during most of the Mississippian time when it formed part of the Antler Highlands, which shed flysch sediments eastward into the Copper basin. The Wood River Formation of Pennsylvanian and Permian age was then deposited over a subdued topography on the Milligen Formation. The Hailey Conglomerate Member at the base of the Wood River filled many irregularities in the surface. This depositional contact later was largely destroyed and the contact between the Milligen and Wood River is now a regional thrust fault at most places.

Idaho↗
USGS1970

North American Devonian conodont biostratigraphy

The Lower Devonian of Nevada provides a reference sequence of nine conodont faunas, five of which are also at Royal Creek, Yukon Territory. The first appearance of Icriodus woschmidti is comparable to that in the lower Gedinnian in Europe; the Polygnathus dehiscens- P. foveolatus lineage correlates with the Emsian. Directly associated graptolite and brachiopod zones in Nevada date the intervening conodont succession as upper Gedinnian and Siegenian. Five faunas characterize the lower Middle Devonian (Eifelian) in New York ; at least two of the lower three are present in the Illinois Basin. Illinois Basin faunas correlative to the upper two New York faunas (Seneca and Cherry Valley) have Icriodus angustus, which is absent in New York, but lack Polygnathus kockelianus, which marks the top of the New York Eifelian. Three faunas subdivide the upper Middle Devonian (Givetian) in the Illinois Basin; the lower two occur in New York and Michigan. The Middle Devonian-Upper Devonian boundary possibly falls at the base of or within beds carrying the Spathognathodus insitus fauna. Alberta and Iowa sequences from the Lower Polygnathus asymmetricus through Upper Palmatolepis gigas Zones closely correspond to the lower Upper Devonian in Germany. An Iowa section yields the standard lower Famennian zonal succession (Middle Palmatolepis triangularis through Upper Palmatolepis quadrantinodosa Zones). Higher Devonian faunas, in the western and central United States, are assigned with difficulty to the Scaphignathus velifer, Upper Polygnathus styriacus, and Spathognathodus costatus Zones. The faunal sequence of the S. costatus Zone differs significantly from that in Germany.

GSA Memoirs↗