Coral Zonation Research Articles

Biostratigraphy and Correlation of McMonnigal and Tor Limestones, Toquima Range, Nevada: GEOLOGICAL NOTES

The McMonnigal Limestone, a predominantly thick-bedded gray limestone bearing a dominantly brachiopod-coral fauna, and the Tor Limestone, a massive limestone bearing a dominantly coral-stromatoporoid fauna, are partly correlative formations thrust together in the Toquima Range, central Nevada. Correlation is based on shelly fossil, graptolite, and conodont faunas. The stratigraphic relation of corals and graptolites from these formations suggests that the Monograptus uniformis and Silurian coral zone E and the Monograptus hercynicus and Devonian coral zone A zones are at least partly coeval.

Spatial Distribution and Pattern of Some Atlantic Reef Corals

THE zonation of stony corals on both Atlantic and Pacific coral reefs has been well documented. Descriptions of coral reefs, wherein communities or associations of species are developed into zones or bands in relation to water depth, wave action and distance from shore, have been published for the Caribbean1–6, and for Pacific reefs7–11. Pattern and horizontal spatial distribution of corals within the respective zones have received little attention12, although certain species have been reported as dominant or exclusive within certain zones1,3,4,8.

Upper Devonian Biostromes and Bioherms on Northeastern Banks Island, Northwest Territories: ABSTRACT

The Mercy Bay Member (Frasnian) is a 200-ft thick limestone unit that is present in the 4,000-ft sequence of terrigenous clastic rocks of the Upper Devonian, Griper Bay Formation of northeastern Banks Island, Northwest Territories. The limestone crops out as extensive steep cliffs and thus affords the detailed study of vertical and lateral facies variations. In the western part of the outcrop area, the Mercy Bay Member is an areally extensive biostrome which within itself consists of bioherms, penecontemporaneous interbiohermal strata, and biostromal beds. The bioherms consist of a lower zone of corals and tabular stromatoporoids in a carbonate-mud matrix and an upper zone almost entirely of massive stromatoporoids. These 2 facies form a massive core. Bedded deposits of coral and stromatoporoid rubble form the flanks of the bioherms. Interbiohermal strata are finely bedded, unfossiliferous, argillaceous micrite. Areally extensive, thick beds, composed almost entirely of massive stromatoporoid colonies, normally overlie the biohermal masses. A vertical sequence of environmental development can be interpreted: the lower coral zone represents a stage of biogenetic mud mounds which formed in the subturbulent zone; the massive stromatoporoid zone represents development of true organic reefs in turbulent water; the massive stromatoporoid biostrome represents a table reef which developed in turbulent water in response to a reduced rate of subsidence. In the east the member consists of isolated bioherms with younger, coarse, terrigenous clastic rocks in the interbiohermal areas. This fact implies that a shelf-to-basin transition occurs from west to east; biostromal deposits characterize the slowly subsiding shelf; bioherms characterize the more rapidly subsiding basin. End_of_Article - Last_Page 846------------

APPLICATION OF DEEP ELECTRICAL SOUNDINGS FOR GROUNDWATER EXPLORATION IN HAWAII

Forty‐five resistivity soundings, using Schlumberger and equatorial dipole electrode configurations, were made on the islands of Oahu and Hawaii to determine the applicability of direct current resistivity methods for locating freshwater aquifers in the State of Hawaii. The soundings were made on the northwestern part of the island of Oahu near the town of Waialua and on the island of Hawaii on the “saddle” area near Pohakuloa and Humuula. Interpretation of 32 sounding curves obtained on the island of Oahu indicates that it is possible to correlate five stratigraphic units underlain by a vesicular basalt basement and that the determination of the approximate depth to the fresh‐water‐saline‐water interface within the basalt is feasible. Two of these Schlumberger soundings with electrode spacings [Formula: see text] reaching 6000 ft yielded sounding curves of the maximum and minimum types whose terminal branches asymptotically approach a resistivity of about 30 ohm‐m, which is believed to be the true resistivity of basalt saturated with sea water. Near the town of Waialua the aquifer is a coral zone as well as parts of the weathered vesicular basalt basement. On the island of Hawaii, near Pohakuloa, an exploratory well drilled in basalt to a depth of 1001 ft (prior to the resistivity survey) proved to be dry. Interpretation of thirteen deep soundings made with Schlumberger and equatorial arrays suggests that the minimum depth to a conductive layer, which may represent basalt saturated with fresh water, is about 2700 ft below land surface. The groundwater appears to be dike impounded.

Carbonate Facies and Coral Zonation, Mississippian, Kogruk Formation, Lisburne Group, Delong Mountains, Brooks Range, Northwestern Alaska: ABSTRACT

The Kogruk Formation, 1,500 to 2,000 ft thick, is composed of marine carbonate rocks deposited in normal-marine to shoal-water environments. Carbonate rock types typically are bryozoan, echinoderm packstone and wackestone, and lesser amounts of calcareous mudstone, and ooid grainstone and packstone. Dolomite and other carbonate sedimentary rocks characteristic of intertidal and supratidal environments are absent in the sections studied. The Kogruk Formation was deposited in an open-marine environment on a subsiding shelf on which carbonate deposition and subsidence were near equilibrium. Only minor oscillations in environments of deposition are seen in a typical section. Lithostrotionid coral faunas are best developed adjacent to the shoal-water facies. Two major coral faunas are recognized. The older, 600-800 ft above the base of the Kogruk Formation, consists of Lithostrotion (Siphonodendron) sinuosum (Kelly), L. (S.) warreni (Nelson), Lithostrotionella mclareni (Sutherland), Thysanophyllum astraeiforme (Warren), Thysanophyllum orientale Thomson, and Sciophyllum lambarti Harker and McLaren. This fauna is of middle Meramecian age. The younger coral fauna is in the highest 600-800 ft of the Kogruk Formation and contains many of the species of lithostrotionids which are present in the lower beds, plus Lithostrotionella aff. L. macouni (Lambe), L. banffensis (Warren), a new species each of Lithostrotionella and Sciophyllum, and two species of Faberophyllum. This fauna is of late Meramecian age. End_of_Article - Last_Page 704------------

Paleoecological Analysis of Corals and Stromatoporoids in a Devonian Biostrome, Falls of the Ohio, Kentucky–Indiana

A single broadly exposed bedding surface in the coral zone of the Middle Devonian Jeffersonville Limestone at the Falls of the Ohio, Kentucky and Indiana, displays a virtually in situ contemporary population of colonial corals and Stromatoporoids. The positions, sizes, shapes, orientations, and subfamilial or generic identities of 14,233 unbroken colonial coelenterates were recorded by detailed quadrat mapping of the bedding surface. The colonial coelenterate fauna (exclusive of branching Favositinae) consists of 70.8 per cent tabulate corals, 25.5 per cent Stromatoporoids, and 3.7 per cent compound rugose corals. These coexisted with numerous solitary rugose corals and pelmatozoans. Stromatoporoids and some tabulate corals concentrated in north–south linear bands in response to ecological conditions, whereas colonial rugose corals were apparently randomly distributed Concentrations of branching Favositinae fragments mark the growth-sites of large colonies. Significant positive and negative linear correlations of paired taxonomic groups indicate tendencies of preferred distribution and concentration among numerically abundant groups. The preferred orientation of the long axes and distal ends of recumbent elongate and massive corals is east–west. Combined evidence suggests that a gentle east–west tidal current, with a stronger easterly component, was responsible for the orientation. The distribution of colonies in the Devonian biostrome is in some ways analogous to the distribution patterns of modern non-reef corals on the South Florida carbonate platform.

New Mississippian Formations and Faunal Zones in Chesterfield Range, Portneuf Quadrangle, Southeast Idaho

Mississippian rocks in the Chesterfield Range, southeast Idaho, consist of the Lodgepole Limestone overlain by a 1,900-foot limestone-sandstone sequence here designated the Chesterfield Range Group. The lower terrigenous part, about 965 feet thick, is the Little Flat Formation; it has a basal siltstone member, a middle sandstone member, and an upper sandy limestone member. The upper carbonate part of the Chesterfield Range Group, here named the Monroe Canyon Limestone, is about 925 feet thick and contains a lower massive member, a medial medium-bedded member, and an upper cherty member. The Chesterfield Range Group is of Late Mississippian age. Three coral zones and four brachiopod zones are recognized. The coral sequence is composed of a lower Eksvasophyllum Zone succeeded by the Faberophyllum Zone and, at the top, the Caninia Zone. The lowest brachiopod zone of Quadratia hirsutiformis is succeeded by the Echinoconchus cf. E. alternatus Zone, the Striatifera brazeriana Zone, and the Spirifer brazerianus Zone. Correlations with Mississippian sequences elsewhere in the northern Rocky Mountains emphasize relationships with the Dry Lake and Old Laketown Canyon sections in northern Utah and with the Deep Creek Mountains section in southeastern Idaho. Relationships with the faunal zones recently established for the Mississippian in western Canada are indicated.

Petrology of the Jeffersonville Limestone (Middle Devonian) of Southeastern Indiana

Thin-section, polished-surface, and X-ray analyses of 500 samples collected from the Jeffersonville Limestone at 14 localities in southeastern Indiana are the basis for detailed correlation of carbonate facies and the reconstruction of sedimentary environments. Basal Jeffersonville sediments were deposited on Louisville Limestone (Niagaran) in southernmost Indiana. In south-central Indiana the Geneva Dolomite rose above the sea floor as a low-relief platform trending east-west. The existence of this platform was reflected throughout deposition of Jeffersonville sediments. The Jeffersonville is subdivided into five zones, each with characteristic fauna and carbonate rock types. The lowest, or coral zone, contains three distinct carbonate facies, including (ascending) grain-supported biomicrite, biosparite, and biomicrudite which overlap one another successively from south to north. The northern limit of sedimentation was controlled by the southern margin of the Geneva platform. The lower biomicrite and biosparite contain many upright branching corals, large corals, and both matlike and moundlike stromatoporoids. The upper biomicrudite contains a profusion of solitary corals and branching-coral fragments. These strata accumulated as a coral bank constructed below effective wave base. The Amphipora-zone sediments comprise biosparite, biosparrudite, biolithite, and biomicrudite in southern Indiana which grade northward into pelsparite which was deposited in shallow waters over the Geneva platform. These pelsparites grade northward into laminated dolomite. Regression of the Jeffersonville sea during deposition of upper Amphipora-zone sediments displaced the pelsparite and laminated dolomite facies southward. Fragments of Amphipora and matlike stromatoporoids are the dominant faunal elements. This zone reflects shoaling over the bank. The Brevispirifer gregarius zone contains grain-supported biomicrite in southernmost Indiana which grades northward into mud-supported biomicrite. The laminated beds continued to accumulate in the shallow shelf lagoon developed on the Geneva platform. Periodic exposure of the lagoon flats produced mud cracks. Charophytes grew in fresh- or brackish-water ponds on the flats, supplying oogonia to marine sediments to the south. Brevispirifer gregarius and echinoderms are the dominant faunal elements. Regression of the sea continued throughout deposition of this zone. The fenestrate bryozoan-brachiopod zone is composed of grain-supported biomicrite and biosparite which intertongue northward with the laminated beds of the shelf lagoon. Fenestrate bryozoans, echinoderms, and brachiopods characterize this zone. Corals and stromatoporoids reappear as significant faunal components. A second major transgression of the Jeffersonville sea is indicated by this zone. The Paraspirifer acuminatus zone is the most widespread of all the Jeffersonville zones and consists of grain-supported biomicrite and biosparite. These sediments are linked genetically to the same transgressive phase as the underlying fenestrate bryozoan-brachiopod zone sediments.

Banff to Shell-Anglo-Canadian Pine Creek No. 1 Well via Bow Valley: ABSTRACT

The first section runs from Mount Rundle to Grotto Mountain in the Bow Valley to the southern end of the Fairholme Range near Exshaw and thence to the bore holes Roxana 1 and Shell-Anglo-Canadian Pine Creek No. 1. The Rocky Mountain formation is present from Mount Rundle to Exshaw and absent eastward owing to pre-Jurassic erosion. The upper Rundle formation at Banff is shown to include the Tunnel Mountain and upper Mount Head members, both of which are present as far east as Exshaw but absent at Pine Creek. The lower Rundle, which is massive at Mount Rundle, gives place eastward to the lower Mount Head, Turner Valley, Shunda, and Pekisko formations. The Banff-Rundle contact is strongly diachronic, the upper Banff at Banff (Spirifer rowleyi) being much younger than the upp rmost Banff in the Foothills and Plains (Leptaena analoga zone) and being the age equivalent of part of the Pekisko and probably the Shunda. The second section follows the strike northward from Pine Creek to the Superior et al. Solomon Creek No. 1 bore hole and thence to Jasper Park (Mount Greenock), Wapiti Lake, B.C. (South Gap), and to the Amerada Crown GF 23-11 bore hole north of Sturgeon Lake. On this section the Rocky Mountain formation is represented by the Permo-Pennsylvanian beds at the top of the Amerada Crown well and by the upper part of the Mount Greenock formation at Jasper. Equivalents of the Tunnel Mountain formation are probably present in the lower part of the Mount Greenock formation at Jasper and in the green sandy shales at the top of the Mississippian at Amerada Crown. The Mount Head formation is present, though thin, in Pine Creek, doubtfully so in Solomon Creek; a coral zone at Jasper suggests that it is there in a relatively pure carbonate facies. At Wapiti Lake it is faunally recognizable (Lithostrotion zone) and the characteristic change from a silty dolomite to the underlying limestone of the Turner Valley formation can be traced to Sturgeon Lake area. The Turner Valley formation is limestone from Jasper north, but dolomite in Solomon Creek and Pine Creek; in both these bore holes there is little or no overlying Mount Head formation. The Shunda formation is in a silt-shale-dark lime facies in the north but becomes anhydritic to the south. The Pekisko is everywhere recognizable and is characterized by oolitic zones. The Banff-Rundle contact retains a relatively constant age along this strike section and wherever there is fossil control the top of the Banff lies in the analoga zone. The Livingstone formation of Douglas appears to be directly correlative with the Dessa Dawn formation of Laudon. End_of_Article - Last_Page 419------------

Fossil Zones of Devonian of Alberta

Devonian strata are known to underlie the greater part of the Great Plains region of Alberta, though generally covered by a thick succession of later rocks. The Devonian rocks are exposed along the fringes of the Plains area where the later rocks have been eroded or where orogenic movements have brought them to the surface. The exposed Devonian rocks have been studied for index fossils which will be helpful in elucidating the various formations penetrated in the Plains area by oil-well operations. The following zones are suggested for the Upper Devonian in descending order: (a) Tornoceras, (b) Cyrtospirifer, (c) Coral, (d) Spirifer jasperensis (divided into two subzones), and (e) Stromatoporoid zone. Apparently the Middle Devonian is not widely spread under the Great Plains. It appears to be accompanied by salt-bearing beds in many places. A few genera and species are suggested for diagnostic purposes, such as Stringocephalus, Atrypa of different species, and Martiniopsis.

Comparative Study of Origin and Distribution of Gulf Coast Tertiary Sediments: ABSTRACT

The Tertiary sediments of the Gulf Coast offer the world's finest available laboratory for a broad study of sedimentation. The deep drilling of the past few years furnishes accurate logs and samples to a depth of about two miles over a large area of relatively undisturbed sediments. The Gulf of Mexico with its shorelines parallel to the strike of the sediments offers a present example of processes and distribution which may be compared to the past. The bottom sample descriptions from Coast and Geodetic Survey charts have been compiled on a map of the Gulf of Mexico. The shape of the Gulf bottom based upon soundings has been studied with respect to the action of currents and waves upon distribution of sediments. The following zones of deposition are outlined and discussed: continental, lagoonal, the sand zone, the mud zone, the coral zone, and the deep sea muds. Four cross sections, exaggerated 20 times vertically, have been drawn from the Cretaceous outcrop across the Gulf. The profiles of the Gulf which accompany the subsurface section relate the present sedimentary zones to those of the past. The detail of the subsurface sections shows a comparison of the various sand groups as to distribution, volume, extent, and probable effects of deltas, currents, and waves. Compared to one another, the sections show the type and relative amount of deposition on different parts of the Gulf Coast and place the time and location of the outstanding depositional events. End_of_Article - Last_Page 929------------

The Correlation of the Fengninian System, the Chinese Lower Carboniferous, as Based on Coral Zones.

The Correlation of the Fengninian System, the Chinese Lower Carboniferous, as Based on Coral Zones.

Note on the Coral zones of the Avonian (lower Carboniferous)

Note on the Coral zones of the Avonian (lower Carboniferous)