Minor Limestone Research Articles

Oxfordian Sedimentation in Western Interior United States

Upper Jurassic (Oxfordian) sediments of the western interior United States were deposited in part of an epicontinental seaway which extended south from the present arctic. This seaway contained a complex of tectonic elements which influenced significantly the geographic distribution of depositional environments. Sedimentation was divided into an initial transgressive phase followed by a regressive phase. Four distinct facies were developed during the transgressive-regressive sequence. (1) The nearshore sand facies, restricted to the western part of the seaway, is characterized by medium- to coarse-grained chert-rich sandstone, chert conglomerate, and wood fragments. The composition, thickness, and geometry of this facies were influenced by the rising westerly source and a preexisting high (the Belt Island trend), as well as by lateral migrations of sediment depocenters. (2) The mud facies was immediately east of the nearshore marine facies. Clay shale, silty shale, siltstone, and argillaceous limestone dominate the rocks of this facies. (3) The mixed carbonate-clay facies developed only in areas removed from the westerly source of sand-size detritus. In such areas, east of the mud facies, sedimentation included both detrital (clay and silt) and chemical (calcium carbonate) components. As a result, this facies consists of highly calcareous clay shale with minor sandy limestone. (4) The marine bar-sand facies developed only during the regressive phase of sedimentation. It consists of a sheet of well-sorted, orthoquartzitic sandstone which was shaped into a eries of submarine sand bars separated by muddy interbar areas. Individual bars were several kilometers in length, and accumulated to a maximum preserved thickness of 15 m. The bars are considered to be of polygenetic origin, resulting from the interplay of storms, tidal currents, and regional circulation currents in the shallow, regressing Oxfordian sea.

Mineralogy and Geochemistry of the Younger Volcanic Islands of Tonga, S.W. Pacific

The Tongan Islands comprise a double island chain, and lie at the northern end of an active island arc extending NNE from northern New Zealand. The eastern chain are limestone covered, with an underlying pre-Upper Eocene gabbro-basalt-andesite series exposed on one island. The active volcanoes, the subject of this paper, form the western island chain, and lie some 100 km above a westward dipping seismic zone. Basaltic andesite dominates the Islands of Hunga Ha'apai and Late (and also Tofua and Kao, which are not described in this paper). Dacite is the main lava of Fonualei and the 1967-68 Metis Shoal eruption. Acid andesites occur only sporadically.Chemically, the lavas are moderately iron-enriched, with relatively low concentrations of K, Rb, Ba, Zr, REE, Pb, and U. K/Rb ratios are 500-700. The lavas are not typically 'calcalkaline'. Phenocryst minerals (normally poorly zoned) are dominated by bytownite with subordinate orthopyroxene, augite, and sometimes pigeonite in the basaltic andesites. Titanomagnetite occurs only in the more silicic andesites and dacites. The pyroxenes show a limited iron enrichment through the series. Coexisting pyroxenes exhibit equilibrium distributions of Mg, Mn, V, Sc, and Ni. Pyroxene partition coefficients for V, Sc. Mn, and Co increase with increasing iron enrichment. Groundmass minerals include intermediate plagioclase, pigeonite, hypersthene, magnetite, plus potash feldspar and quartz in the dacites. The Metis Shoal lava consists of rhyolitic glass with xenocrysts of forsteritic olivine and enstatite and phenocrysts of bytownite, hypersthene, augite, and titanomagnetite.The basaltic andesites are interpreted to be the product of direct peridotitic fusion within the mantle, presumably in the region overlying the seismic zone, and modified by olivine fractionation during ascent. Least squares numerical calculations, using major and trace element data, support the derivation of the more siliceous lava compositions by low pressure crystal fractionation of basaltic andesite Sr/Sr ratios exhibit a small range of variation (0.7036-0.7043), possibly indicative (except for the Metis Shoal lava) of minor limestone (?) contamination within the more silicic lavas during fractionation.

What is Franciscan?

Newly established early Cenozoic fossil localities within the coastal belt of Franciscan rocks recall the furor which developed before the last decade over occurrences of Cretaceous fossils within the Franciscan Formation of presumably Late Jurassic age. It is timely to consider again the question--what is Franciscan?--not only in regard to what physically constitutes the Franciscan, but also to what it should be called. The Franciscan is herein designated a complex, and is defined as the folded, faulted, and stratally disrupted basement terrane of the California Coast Ranges--including extensions into Oregon and Mexico--which is composed of graywacke, shale, minor conglomerate, radiolarian chert and siliceous shale, minor limestone, volcanic rocks, mafic-ultramafic p utonic rocks, and their zeolite-to-blueschist-facies metamorphic equivalents. Thus, the Franciscan Complex is shown to have both structural and lithologic significance. Other terms used in connection with Franciscan rocks are also defined.

Geology of Central Grant Range, Nevada

Approximately 26,000 ft (7,930 m) of Paleozoic carbonate and subordinate clastic sedimentary rocks is exposed in the central Grant Range. Cambrian quartzite, shale, and minor limestone are the oldest exposed rocks in the area. The overlying 11,200 ft (3,416 m) consists of limestone, dolomite, shale, and minor quartzite and sandstone; this sequence begins with the Ordovician Pogonip Group and ends with the Mississippian Joana Limestone. The overlying strata are Upper Mississippian and Pennsylvanian shale, and minor sandstone and limestone. The Paleozoic sequence is overlain unconformably by Cenozoic sedimentary and volcanic rocks. Three major low-angle faults that separate younger rocks from older are exposed in the area. They are, in ascending order, the Grant Canyon, Heath Canyon, and Beaty Canyon faults. The Grant Canyon fault emplaces gently dipping Middle Cambrian limestone and shale over steeply dipping Lower Cambrian Prospect Mountain Quartzite. Rocks considered to be Lower Ordovician are separated from overlying Cambrian units by the Heath Canyon fault. The Beaty Canyon fault generally carries concordant Silurian through Pennsylvanian strata over Lower Ordovician rocks. Relative eastward movement of the upper plate rocks is demonstrated by folds in the lower plates, which are overturned to the east. In addition, five subordinate low-angle faults are recognized. Synorogenic regional metamorphism, predating the faulting, converted part of the Cambrian and Lower Ordovician strata into tectonically banded marbles, and chlorite-muscovite and biotite phyllites. Postmetamorphic low-angle faulting resulted in superposed local mylonitization. Medium- to high-grade calc-silicate rocks are associated with a granitic intrusion. Folding within the range is locally intense, and high-angle faulting, with the exception of the range front fault or faults, is mostly of small displacement. A Mesozoic age of metamorphism and thrusting is inferred from regional evidence.

Geology of the North Slope of the Puerto Rico Trench

We use bathymetric and continuous seismic reflection profiles and rocks dredged in 1962 and 1964 to described topography, stratigraphy and structure of the North Slope of the Puerto Rico Trench between 65° 00′W and 66° 30′W. Abundant basalt, chert, pink and green claystone and minor limestone and soft mudstone were dredged from 3200–3700 fms at 20° 16′N, 65° 42′W. The basalt has porphyritic, amygdular or diabasic texture, is partly altered to montmorillonitic clay, contains plagioclase which is mainly labradorite or bytownite, is low in potassium and titanium, and is normally tholeiitic.The tentative stratigraphic succession of the North Slope is as follows: (1) Cenomanian basalt flows, possibly interbedded with chert, claystone and limestone, form the oceanic basement, and have compressional velocity near 5 km/sec. (2) Consolidated sediment, with compressional velocity of 3·0–4·5 km/sec, possibly not present everywhere, lies unconformably on the basement. Age is Late Cretaceous and Early Tertiary, and maximum thickness 300 m. (3) Acoustically transparent unconsolidated sediment mantles the basement and the consolidated sediment. Age is Late Tertiary and Quaternary, compressional velocity 1·5–2·6 km/sec, and maximum thickness 400 m. (4) Acoustically layered flat-lying unconsolidated sediment lies in east-west valleys in the North Slope, and forms the abyssal plain at the bottom of the Trench. Maximum thickness in the valleys is 500 m.Present evidence from echo-sounding and seismic reflection profiles is insufficient to indicate whether the scarps, ridges and valleys of the North Slope were formed by thrusting, normal faulting strike-slip faulting or gravity sliding or from a combination of these processes.

Petrographic Analysis of Bird Spring Group (Carboniferous-Permian) Near Lee Canyon, Clark County, Nevada

The thick section of the Bird Spring Group near Lee Canyon, Clark County, Nevada, consists of more than 7,000 feet of predominantly carbonate strata which are subdivided as follows: Chesterian (125±feet), Morrowan (775±feet), Atokan (510±feet), Desmoinesian (520±feet), Missourian (145±feet), Virgilian (525±feet), Wolfcampian (3,075±feet), and Leonardian (1,525±feet). The upper limits of the group could not be determined because of truncation by faulting. A petrographic study was made on the Bird Spring Group near Lee Canyon, and, for descriptive purposes, a classification of carbonate rocks was modified from several existing classifications. That classification is used in this paper. Quartzose sandstone and siltstone, biocalcarenite, biocalcirudite, and biocalcarenitic limestone, with minor fine-grained limestone and calcareous shale constitute the Chesterian rocks and represent reworking in an advancing sea. The body of information now available on Great Basin late Paleozoic stratigraphy indicates major source areas on the northwest, northeast, and east. The relative contribution of each of those regions to the lower several scores of feet in the Bird Spring is not known. Morrowan beds indicate a gradual change to unstable shelf conditions which later altered to stable shelf conditions. Biocalcarenite grades upward through biocalcarenitic and skeletal calcarenitic limestone into silty fine-grained limestone and calcareous shale. Gradation is then back to skeletal calcarenitic and biocalcarenitic limestone and calcarenite. Fish remains are common in these and in the overlying Atokan and Desmoinesian strata. Open shelf conditions prevailed in Atokan and Desmoinesian time when coral and algal biolithites formed. Komia contributed abundantly to this interval and Chaetetes is present in the Atokan portion. Associated with these bioconstructed limestones in a cyclical fashion are biocalcarenite, biocalcarenitic, and skeletal calcarenitic limestone, pelletal limestone, and siltstone. Missourian, Virgilian, and lower Wolfcampian rocks record a change, inaugurated in late Desmoinesian, to unstable shelf conditions and greater influx of terrigenous matter. Impure skeletal-bearing, fine-grained, and skeletal calcarenitic limestone are most abundant in the l wer part of the interval; fossil content increases upward and the uppermost beds are crinoidal biocalcirudites. In late Wolfcampian time, rather abrupt change was to mostly deeper quieter waters. Anaerobic conditions prevailed in the early late Wolfcampian, but restriction later diminished. Convolute laminae and slump structures in mudstone and fine-grained limestone attest to periods of contemporaneous deformation. Intermittently, the waters shallowed and the sea bottom was heavily populated with gastropod-hydrozoan-crinoid-foraminifer-bryozoan-algal communities. Gradually the sedimentary framework reverted to that of an open shelf dominated by biostromal and coral development. At the time the uppermost Bird Spring was deposited, physico-chemical and biochemical precipitation were impor ant, and so oolite calcarenite and algal-pelletal limestone were deposited. The Permian climate in the region was probably arid to semi-arid. It is suggested that the Bird Spring section near Lee Canyon be elevated to group status and appropriate subdivision be made. Indian Springs Formation qualifies for the Chester-lower Morrow portion. The End_Page 1657------------------------------ remainder of the Pennsylvanian and lower Wolfcamp beds constitute another logical subdivision. The upper Wolfcamp sequence may deserve formational rank as well as the uppermost Wolfcamp-Leonard interval. Great thickness of the Bird Spring near Lee Canyon is due primarily to the Wolfcamp sequence, a situation which merits attention when distinguishing between platform and miogeosyncline.

Stratigraphy and Structure at the North End of the Taconic Range in West-Central Vermont

The stratigraphy of the Taconic sequence at the north end of the Taconic Range in west-central Vermont has been revised as follows: Pawlet formation: interbedded black slate and greywacke; Middle Ordovician Mount Hamilton group: undivided black, gray, green, and red argillite, with minor limestone, limestone conglomerate, and ankeritic quartzite; Upper Cambrian to Middle Ordovician West Castleton formation: black slate and phyllite, with a limestone unit near the base; Lower Cambrian Bull formation: Lower Cambrian (1) Mettawee facies. Purple and green slate, mudstone, and phyllite; this facies constitutes the bulk of the formation. (2) North Brittain conglomerate member. An intraformational limestone-pebble, slate-matrix conglomerate (3) Mudd Pond member. A thin but persistent orthoquartzite (4) Zion Hill member. A discontinuous graywacke or sub-graywacke unit ranging from a pebble conglomerate to a mudstone (5) Bomoseen member. A massive, olive-drab, medium-grained graywacke Biddie Knob formation: a chloritoid-bearing purple and green slate and phyllite with minor beds of limestone and quartzite. Lower Cambrian (?) The sense of the Lower Cambrian succession is given by load casting and graded bedding in the Zion Hill, and in rare arkoses mapped with the Bomoseen. The sense of succession in the Mount Hamilton group is given by cross-bedding, graded bedding, and by channel filling. Structurally, the Taconic sequence consists of nested thrust slices subsequently folded together. Although each slice has its own characteristic stratigraphy and structure, correlation of the units, down to the formational level, presents little difficulty. The structure is typified by the Giddings Brook recumbent bottoming fold in the area between the Taconic Range and Lake Bomoseen. The fold is at least 5 miles in amplitude, the movement was cast to west, and the axial plane is nearly horizontal. Digitations on this major structure explain the map pattern. Key units of the Taconic sequence have been recognized east of the Taconic Range; the east flank of the Range is now underlain by an inverted sequence of Lower Cambrian rocks. The Sudbury nappe at the north end of the map area is composed of the Lower Ordovician Chip-man formation. The structure does not root in the east limb of the Middlebury synclinorium as reported by Cady, but is a thrust slice, whose southeast edge tucks under the Taconic sequence. Structurally, this unit is part of the latter. The Whipple marble at the north end of Whipple Hollow is part of the Lower Ordovician Bascom formation, which in this area has been moved westward over the younger black phyllite through a recumbent fold involuted into the Taconic sequence. This structure indicates the persistence of intense deformation after the development of the Taconic structure. Topologically, the Taconic sequence is in the southward continuation of the Middlebury synclinorium. Coupled with the discovery of the inverted Lower Cambrian rocks east of the Taconic skyline, the evidence supports an allochthonous origin of the Taconic sequence. The gradational contact between the green and black phyllites east of the Taconic Range, and the presence in the black phyllite of beds characteristic of the Taconic sequence show that part of the black phyllite here is allochthonous. The thrusting is dated as Late Trenton on the basis of exotic blocks of Taconic rocks in an autochthonous black slate at Forbes Hill. Similar rocks have also been found elsewhere at the periphery of the Taconic sequence. The thrusting may have occurred as submarine gravity slides of soft rocks; slump structure is indeed abundant in the Taconic sequence. The intimate mixing of the black slates of the Taconic sequence and of the Trenton mud may make the mapping of the Taconic fault unfeasible even in principle. Continued deposition of black mud after the emplacement of the Taconic nappes could account for the reported Trenton unconformity at the margin of the Taconic sequence south of the Castleton area. The Taconic sequence probably was deposited in the area of the present Green Mountains. The upper part of the Mount Hamilton group correlates by fossils with the Moretown-Cram Hill formations of eastern Vermont. The Mount Hamilton group is free of volcanic rocks and is thin, in contrast with the Moretown-Cram Hill formations; this change is consistent with paleogeographical requirements, as the Cambro-Ordovician, typically eugeosynclinal deposits of eastern Vermont, must somehow change into the synchronous, but typically miogeosynclinal deposits of western Vermont and eastern New York.

Structural Development and Paleozoic Stratigraphy of Black Mesa Basin, Northeastern Arizona, and Surrounding Areas

Paleozoic sedimentary rocks in the subsurface of the Black Mesa basin of northeastern Arizona include 0-800 feet of Cambrian dolomite, sandstone, shale, and minor limestone, 0-300 feet of Devonian dolomite and sandstone, 0-500 feet of Mississippian dolomite and limestone, 0-500 feet of Pennsylvanian redbeds and limestone, and about 1,000-2,000 feet of Permian redbeds and eolian sandstone capped by 0-400 feet of dolomite near the western edge of the basin. These rocks do not crop out and only a few wells have penetrated them to date. Isopach and lithofacies maps show that in all Paleozoic systems the thick marine carbonate sections of northwestern Arizona and southwestern Utah pinch out, become more clastic, or interfinger with continental sedimentary rocks in the direction of the Black Mesa. At no time during the Paleozoic or Mesozoic eras was the Black Mesa a basin in the sense that it was the site of deposition of marine sediments significantly thicker than in surrounding areas. A structural basin was formed by differential uplift in Cenozoic time. When the entire Colorado Plateau was uplifted, the Black Mesa area rose 3,500-7,000 feet less than the surrounding country. Possibilities for oil and gas discoveries in stratigraphic traps seem best in the northern and western parts of the Black Mesa basin, where a moderately thick Paleozoic marine section is present and where complex facies changes occur in rocks of several Paleozoic systems. Chances are poor in the eastern part of the basin, which lies on the western flank of the Defiance positive area, a structural high that persisted through much of Paleozoic time. In general, the Black Mesa basin has a much thinner marine sedimentary section than the nearby San Juan, Blanding (Paradox), Henry, and Kaiparowits basins.

Petrology of Tamworth Group, Lower and Middle Devonian, Tamworth-Nundle District, New South Wales

ABSTRACT The Tamworth Group is dominantly of deep-water origin and consists largely of graywacke rudites, graywackes, and argillities. The latter usually contain radiolaria. Lithic labile graywackes are dominant and consist chiefly of andesitic detritus (rock fragments, plagioclase, ferromagnesians, chlorite, and accessories) with minor rhyolitic, granitic, and older sedimentary components. They are thought to have originated in complex island arcs. Minor feldspathic labile graywacke and argillaceous limestone occurs. The former is thought to be largely of andesitic origin, being redistributed crystal tuff with admixed plutonic quartz. The limestones, small silty lenses, are probably the result of calcification during early diagenesis. The feldspar in most of the group is now albitised, but relics of andesine-labradorite remain occasionally. The Drik-Drik Formation low in the sequence is largely coarse keratophyric detritus, heavily hematitised and scarcely transported. It may be a shallow-water deposit derived from the underlying Copes Creek Keratophyre, or from contemporaneous volcanics on an adjoining land-mass.

Paleozoic Stratigraphy of Black Mesa Basin, Northeastern Arizona and Surrounding Areas: ABSTRACT

Paleozoic sedimentary rocks in the subsurface of the Black Mesa basin of northeastern Arizona include: 0-800 feet of Cambrian dolomite, sandstone, shale, and minor limestone; 0-300 feet of Devonian dolomite and sandstone; 0-500 feet of Mississippian dolomite and limestone; 0-500 feet of Pennsylvanian redbeds and limestone; and about 2,000 feet of Permian redbeds and eolian sandstone capped by 0-400 feet of dolomite near the western edge of the basin. These rocks do not crop out, and only a few wells have penetrated them to date. Isopach and lithofacies maps show that in all Paleozoic systems the thick marine carbonate sections of northwestern Arizona and southwestern Utah pinch out, become more clastic, or interfinger with continental sedimentary rocks southeast in the direction of the Black Mesa. At no time during the Paleozoic or Mesozoic era was the Black Mesa area a basin in the sense that it was the site of deposition of marine sediments significantly thicker than in surrounding areas. The Black Mesa structural basin was formed by differential uplift in Cenozoic time. When the Colorado Plateau was uplifted the Black Mesa rose 3,500-7,000 feet less than surrounding areas. Possibilities for oil and gas discoveries in stratigraphic traps seem best in the northern and western parts of the Black Mesa basin, where several permeable formations appear to pinch out. End_of_Article - Last_Page 1096------------

THE YOREDALE SERIES OF UPPER WENSLEYDALE AND ADJACENT PARTS OF NORTH-WEST YORKSHIRE

Summary The type succession for the Yoredale Series is slightly amended at the base to include the Hawes Limestone, a name resurrected for the topmost beds (parts of D 1 and D 2 ) of the Great Scar Limestone. The lateral variations of the series, up to the top of the Main Limestone, are described in detail, particularly the “Non-Calcareous Measures” between the major limestones. These may contain minor limestones, capable of limited correlation, as in the Hardrow Scar and Simonstone Cyclothems. The rock types are compared with those of a modern delta and an extensive correlation is found possible, leading to the suggestion that the Yoredale Series results from the intermittent deltaic invasions of a shallow limestone sea. It is deduced that periodic diversions of the delta river produced silting up of the main channel upstream; regional subsidence carried the abandoned delta below sea-level and limestone was deposited. During this time the river was building up a second delta to the east which eventually was similarly abandoned, and the river returned to its old course. Repetition of these events produced the Yoredale Series.

Devonian Stratigraphy of Sulphur Springs and Pinyon Ranges, Nevada

Four widespread and distinctive lithologic subdivisions of the autochthonous Devonian strata, the of Hague, are recognized in an area 25-70 miles north of Eureka, Nevada. The three lower units, (1) the McColley Canyon member of limestone and dolomitic limestone, (2) the Union Mountain member of quartzite, quartzitic dolomite, and dolomite, and (3) the Telegraph Canyon member of light- and dark-banded mottled dolomite with a minor limestone tongue, are placed within the Nevada formation as redefined by Nolan, Merriam, and Williams. The uppermost unit, consisting of limestone truncated above by the Roberts Mountains overthrust, is assigned to the Devils Gate limestone, similarly redefined. The Nevada formation contains faunas ranging from those of the Trematospira (Oriskany) zone to Stringocephalus and Stromatoporoid-Cladopora (Middle Devonian). The Devils Gate limestone faunas range in age from Middle Devonian to early Late Devonian. The Nevada formation is regarded as a lithic correlative of the Simonson and the major part, if not all, of the Sevy dolomites of western Utah and possibly of parts of the Hidden Valley and Lost Burro formations of the Panamint Range, California. The Devils Gate limestone is considered an equivalent of the Guilmette formation of western Utah.