| Kettle Point Formation | |
|---|---|
| Stratigraphic range: Late Devonian | |
| Type | Geological formation |
| Underlies | Pleistocene glacial till or Mississippian Bedford Formation |
| Overlies | Hamilton Group |
| Thickness | average of 100 feet (30 m) to maximum of 360 feet (110 m) in drill holes |
| Lithology | |
| Primary | bituminous shales |
| Other | shale and siltstone interbeds |
| Location | |
| Location | Kettle Point Park, Ontario |
| Region | southern Ontario |
| Country | Canada |
| Type section | |
| Named for | Kettle Point, Ontario |
| Named by | J. F. Caley |
| Location | Kettle Point Park, Ontario |
| Year defined | 1943 |
| Coordinates | 43°10′59.41″N82°1′3.11″W / 43.1831694°N 82.0175306°W |
| Region | Southeast shore of Lake Huron |
| Country | Ontario, Canada |
| Thickness at type section | 12 feet (3.7 m) exposed along shoreline |
The Kettle Point Formation, also known as the Kettle Point (black) Shale, is a geologic formation that consists of thinly laminated, siliciclastic, organic-rich black shale with thin to thick interbeds of organic-poor mudstone. It is largely restricted to the subsurface of southwestern Ontario. [1] [2]
The eponymous type location of the Kettle Point Formation is Kettle Point which is located on the southeast shore of Lake Huron, southwestern Ontario. Kettle Point is the sole significant, and relatively accessible, outcrop of this formation. The outcrop consists of a wave-cut bluff which is 6.5 feet (2.0 m) high. Along its length, the wave-cut bluff exposes 12 feet (3.7 m) of slightly tilted shale. Kettle Point was named for decimetre- to meter-sized, hemispherical to spheroidal authigenic carbonate concretions that erode out of the Kettle Point Formation. These concretions are locally called kettles due to their resemblance to cooking vessels used by European settlers. [2] [3]
In 1863, Logan first informally described the strata comprising the Kettle Point Formation as the Kettle Point black shale and its outcrop at Kettle Point. [4] In 1900, Dadly described the shales and concretions, locally called kettles, and their outcrop at Kettle Point in detail. [5] His descriptions of them have been used and cited by later researchers. Caley first formally named and defined the Kettle Point beds in 1943. [6] Later in 1955, Sanford and Brady redefined it to include only those beds that occur between the top of the Hamilton Formation and the base of the Port Lambton beds. [7] Further detailed descriptions of this unit were published by MacDonald [8] and Russell. [1]
The Kettle Point Formation of consists of organic-rich laminated black shale interbedded with beds of organic-poor greyish green mudstones and rare red and red–beige mudstones. The black shales of the Kettle Point Formation are organic-rich and highly fissile. Some layer of black shale are interlaminated with white-coloured laminae of clay- to silt-sized quartz and calcite grains. The associated greyish green mudstones are homogeneous, lacking discernible lamination or other primary sedimentary structures. Furthermore, they lack the organic matter and microfossils, i.e. Tasmanites , which are abundant in the black shale. The beds of greyish green mudstones occur interbedded with beds of black shale. Thin, < 4 in (10 cm) (average 0.8–1.2 in (2.0–3.0 cm)), beds of red and red–beige mudstone were observed in three drill holes of the Kettle Point Formation. The homogeneous red and red–beige mudstones are significantly lower in mud content than the greyish green mudstones and have a microcrystalline appearance. The reddish color is due to small siderite crystals that are less than 0.4 in (10 mm) in diameter. [1] [2]
The concretions that are found within the Kettle Point Formation are typically spheres to oblate spheroids. The oblate spheroids are flattened slightly parallel to the plane of bedding. The diameters of these concretions range from 1–1.5 feet (0.30–0.46 m). The fragments of these concretions display internal fabric that consists of an inner homogeneous, commonly burrowed zone surrounded by an outer zone of radiating fibrous carbonate. These concretions lack any obvious nuclei, such as macrofossils, at their centers. These concretions occur in the black shale in the lower part of the Kettle Point Formation. Because the concretions are so much harder than the enclosing weakly indurated shale, they readily weather out of the shale along the shoreline and are incorporated into the rubble mantling the lake bottom adjacent to the outcrop. [3] [5]
The lower contact of the Kettle Point Formation is a disconformity that lies on the uneven surface of the underlying Hamilton Group. The uneven topography of the basal contact is the result of a combination of the dissolution of the underlying Silurian Salina Salt and erosion of the underlying Hamilton Group. At Kettle Point, the black shales of the Kettle Point Formation rest directly upon a layer of "conodont hash", which in turn rest upon a 8.3 in (21 cm)-thick bed of chert. This cherts lies upon chert intercalated with limestone of the Hamilton Group. [1] [2] [9]
The upper contact of the Kettle Point Formation is an erosional unconformity. Typically in southern Ontario, it is directly overlain by Pleistocene glacial tills and related deposits. In the central part of southern Ontario, the Carboniferous Bedford Formation of the Port Lambton Group unconformably rests upon Kettle Point Formation. Locally, sandstone-filled fluvial channels of the Berea Formation have removed the Bedford Formation and cut into the Kettle Point Formation. [1] [2]
Except for Tasmanites and conodonts, the flora and fauna of the Kettle Point Formation is very limited in terms of diversity as well as in number. Within the Kettle Point Formation, only Tasmanites, an orange or amber colored cyst of a marine planktonic alga, is abundant on typical bedding planes and within concretions. Conodonts are also common and less commonly ostracods, scolecodonts, arenaceous foraminiferans, and pyritized radiolarians and sponge spicules have also been observed. Rare megafossils include plant remains (e.g. Callixylon and Protosalvinia), the inarticulate brachiopod, Lingula, and fish remains (scales, dermal plates, and possible teeth). [2] [10] [11] Small, unidentified, highly fragmented brachiopods and crinoids have been recovered from drill cuttings. [8] Finally, well-preserved, silicified fossils of Prototaxites have been observed and collected from the black shales of the Kettle Point Formation at Kettle Point. [12]
The analysis of conodonts concluded that the strata comprising the Kettle Point Formation range in age from Frasnian and Famennian (Late Devonian). These conodonts faunas are also interpreted to indicate that the Kettle Point Formation is stratigraphically equivalent to more extensive organic-rich, fine-grained strata, e.g. the Ohio, New Albany, Chattanooga, and Antrim shales, of the eastern United States. It is also considered to be stratigraphically equivalent to organic-rich, fine-grained strata, the Long Rapids Formation, of the Hudson Bay platform in northern Ontario. [10] [11]
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2Si2O5(OH)4) and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite. Shale is characterized by its tendency to split into thin layers (laminae) less than one centimeter in thickness. This property is called fissility. Shale is the most common sedimentary rock.
The Llano Uplift is a geologically ancient, low geologic dome that is about 90 miles (140 km) in diameter and located mostly in Llano, Mason, San Saba, Gillespie, and Blanco counties, Texas. It consists of an island-like exposure of Precambrian igneous and metamorphic rocks surrounded by outcrops of Paleozoic and Cretaceous sedimentary strata. At their widest, the exposed Precambrian rocks extend about 65 miles (105 km) westward from the valley of the Colorado River and beneath a broad, gentle topographic basin drained by the Llano River. The subdued topographic basin is underlain by Precambrian rocks and bordered by a discontinuous rim of flat-topped hills. These hills are the dissected edge of the Edwards Plateau, which consist of overlying Cretaceous sedimentary strata. Within this basin and along its margin are down-faulted blocks and erosional remnants of Paleozoic strata which form prominent hills.
The geology of Shropshire is very diverse with a large number of periods being represented at outcrop. The bedrock consists principally of sedimentary rocks of Palaeozoic and Mesozoic age, surrounding restricted areas of Precambrian metasedimentary and metavolcanic rocks. The county hosts in its Quaternary deposits and landforms, a significant record of recent glaciation. The exploitation of the Coal Measures and other Carboniferous age strata in the Ironbridge area made it one of the birthplaces of the Industrial Revolution. There is also a large amount of mineral wealth in the county, including lead and baryte. Quarrying is still active, with limestone for cement manufacture and concrete aggregate, sandstone, greywacke and dolerite for road aggregate, and sand and gravel for aggregate and drainage filters. Groundwater is an equally important economic resource.
The Ecca Group is the second of the main subdivisions of the Karoo Supergroup of geological strata in southern Africa. It mainly follows conformably after the Dwyka Group in some sections, but in some localities overlying unconformably over much older basement rocks. It underlies the Beaufort Group in all known outcrops and exposures. Based on stratigraphic position, lithostratigraphic correlation, palynological analyses, and other means of geological dating, the Ecca Group ranges between Early to earliest Middle Permian in age.
The Hamilton Group is a Devonian-age geological group which is located in the Appalachian region of the United States. It is present in New York, Pennsylvania, Maryland, Ohio, West Virginia, northwestern Virginia and Ontario, Canada, and is mainly composed of marine shale with some sandstone.
The Marcellus Formation or the Marcellus Shale is a Middle Devonian age unit of sedimentary rock found in eastern North America. Named for a distinctive outcrop near the village of Marcellus, New York, in the United States, it extends throughout much of the Appalachian Basin.
Marinite is a gray to dark-gray or black oil shale of marine origin in which the chief organic components are lamalginite and bituminite derived from marine phytoplankton, with varied admixtures of bitumen, telalginite and vitrinite. Marinite deposits are the most abundant oil-shale deposits. They are generally widespread but at the same time they are relatively thin and often of restricted economic importance. Typical environments for marinite deposits are found in epeiric seas.
The Bedford Shale is a shale geologic formation in the states of Ohio, Michigan, Pennsylvania, Kentucky, West Virginia, and Virginia in the United States.
The Exshaw Formation is a stratigraphic unit in the Western Canada Sedimentary Basin. It takes the name from the hamlet of Exshaw, Alberta in the Canadian Rockies, and was first described from outcrops on the banks of Jura Creek north of Exshaw by P.S. Warren in 1937. The formation is of Late Devonian to Early Mississippian age as determined by conodont biostratigraphy, and it straddles the Devonian-Carboniferous boundary.
The Phosphoria Formation of the western United States is a geological formation of Early Permian age. It represents some 15 million years of sedimentation, reaches a thickness of 420 metres (1,380 ft) and covers an area of 350,000 square kilometres (140,000 sq mi).
The Gravelbourg Formation is a stratigraphical unit of Bajocian age in the Western Canadian Sedimentary Basin.
The Shadow Lake formation is a geological unit that crops out in Southern Ontario, Canada and northern Pennsylvania, United States. The shaly sections act as a caprock to petroleum reservoirs.
The Hakatai Shale is a Mesoproterozoic rock formation with important exposures in the Grand Canyon, Coconino County, Arizona. It consists of colorful strata that exhibit colors varying from purple to red to brilliant orange. These colors are the result of the oxidation of iron-bearing minerals in the Hakatai Shale. It consists of lower and middle members that consist of bright-red, slope-forming, highly fractured, argillaceous mudstones and shale and an upper member composed of purple and red, cliff-forming, medium-grained sandstone. Its thickness, which apparently increases eastwards, varies from 137 to 300 m. In general, the Hakatai Shale and associated strata of the Unkar Group rocks dip northeast (10–30°) toward normal faults that dip 60° or more toward the southwest. This can be seen at the Palisades fault in the eastern part of the main Unkar Group outcrop area. In addition, thick, prominent, and dark-colored basaltic sills and dikes cut across the purple to red to brilliant orange strata of the Hakatai Shale.
The Surprise Canyon Formation is a geologic formation that consists of clastic and calcareous sedimentary rocks that fill paleovalleys and paleokarst of Late Mississippian (Serpukhovian) age in Grand Canyon. These strata outcrop as isolated, lens-shaped exposures of rocks that fill erosional valleys and locally karsted topography and caves developed in the top of the Redwall Limestone. The Surprise Canyon Formation and associated unconformities represent a significant period of geologic time between the deposition of the Redwall Limestone and the overlying Supai Group.
The Cleveland Shale, also referred to as the Cleveland Member, is a shale geologic formation in the eastern United States.
The Milwaukee Formation is a fossil-bearing geological formation of Middle Devonian age in Milwaukee County, Wisconsin. It stands out for the exceptional diversity of its fossil biota. Included are many kinds of marine protists, invertebrates, and fishes, as well as early trees and giant fungi.
The Huntersville Chert or Huntersville Formation is a Devonian geologic formation in the Appalachian region of the United States. It is primarily composed of mottled white, yellow, and dark grey chert, and is separated from the underlying Oriskany Sandstone by an unconformity. The Huntersville Chert is laterally equivalent to the Needmore Shale, which lies north of the New River. It is also laterally equivalent to a sandy limestone unit which is often equated with the Onondaga Limestone. These formations are placed in the Onesquethaw Stage of Appalachian chronostratigraphy, roughly equivalent to the Emsian and Eifelian stages of the broader Devonian system.
The Whitehill Formation, alternatively written as White Hill Formation and formerly known as White Band or Whitehill or White Hill Member, is a regional Early Permian geologic formation belonging to the Ecca Group in the southeastern ǁKaras Region of southeastern Namibia and Eastern, Northern and Western Cape provinces of South Africa.
The Nod Glas Formation is an Ordovician lithostratigraphic group in Mid Wales. The rock of the formation is made up of pyritous, graptolitic mudstone that is generally black in colour. It weathers to a soft, very well cleaved and coal-like material. The formation runs from Conwy in the north, down to Cardigan Bay in the area around Aberdyfi and Tywyn, though it is not a continuous over this area.
This article describes the geology of Dartmoor National Park in Devon, in south-west England. Dartmoor gained national park status in 1951 but the designated area of 954 km2 (368 sq mi) extends beyond the upland of Dartmoor itself to include much of the surrounding land, particularly in the northeast. The geology of the national park consists of a 625 km2 (241 sq mi) core of granite intruded during the early Permian period into a sequence of sedimentary rocks originating in the Devonian and Carboniferous periods. These rocks were faulted and folded, sometimes, intensely, during the Variscan orogeny. Thermal metamorphism has also taken place around the margins of the granite pluton altering the character of the sedimentary rocks whilst mineral veins were emplaced within the granite. A small outlier of Palaeogene sediments occurs on the eastern boundary of the national park.
