Early dolomitization of a Lower Cretaceous shallow water carbonate platform: was microbial activity a major controlling factor?

2010 ◽  
pp. EEP24
Author(s):  
Iain Andrew MacDonald
Keyword(s):  
Shallow Water ◽  
Microbial Activity ◽  
Lower Cretaceous ◽  
Carbonate Platform ◽  
Controlling Factor ◽  
Major Controlling Factor ◽  
Water Carbonate ◽  
Shallow Water Carbonate

Cambrian shelf stratigraphy of North Greenland

1997 ◽  
pp. 1-120 ◽  
Author(s):  
Jon R. Ineson ◽  
John S. Peel
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Carbonate Platform ◽  
Outer Shelf ◽  
Early Cambrian ◽  
Middle Cambrian ◽  
Water Trough ◽  
Water Carbonate ◽  
Shallow Water Carbonate ◽  
North Greenland

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Ineson, J. R., & Peel, J. S. (1997). Cambrian shelf stratigraphy of North Greenland. Geology of Greenland Survey Bulletin, 173, 1-120. https://doi.org/10.34194/ggub.v173.5024 _______________ The Lower Palaeozoic Franklinian Basin is extensively exposed in northern Greenland and the Canadian Arctic Islands. For much of the early Palaeozoic, the basin consisted of a southern shelf, bordering the craton, and a northern deep-water trough; the boundary between the shelf and the trough shifted southwards with time. In North Greenland, the evolution of the shelf during the Cambrian is recorded by the Skagen Group, the Portfjeld and Buen Formations and the Brønlund Fjord, Tavsens Iskappe and Ryder Gletscher Groups; the lithostratigraphy of these last three groups forms the main focus of this paper. The Skagen Group, a mixed carbonate-siliciclastic shelf succession of earliest Cambrian age was deposited prior to the development of a deep-water trough. The succeeding Portfjeld Formation represents an extensive shallow-water carbonate platform that covered much of the shelf; marked differentiation of the shelf and trough occurred at this time. Following exposure and karstification of this platform, the shelf was progressively transgressed and the siliciclastics of the Buen Formation were deposited. From the late Early Cambrian to the Early Ordovician, the shelf showed a terraced profile, with a flat-topped shallow-water carbonate platform in the south passing northwards via a carbonate slope apron into a deeper-water outer shelf region. The evolution of this platform and outer shelf system is recorded by the Brønlund Fjord, Tavsens Iskappe and Ryder Gletscher Groups. The dolomites, limestones and subordinate siliciclastics of the Brønlund Fjord and Tavsens Iskappe Groups represent platform margin to deep outer shelf environments. These groups are recognised in three discrete outcrop belts - the southern, northern and eastern outcrop belts. In the southern outcrop belt, from Warming Land to south-east Peary Land, the Brønlund Fjord Group (Lower-Middle Cambrian) is subdivided into eight formations while the Tavsens Iskappe Group (Middle Cambrian - lowermost Ordovician) comprises six formations. In the northern outcrop belt, from northern Nyeboe Land to north-west Peary Land, the Brønlund Fjord Group consists of two formations both defined in the southern outcrop belt, whereas a single formation makes up the Tavsens Iskappe Group. In the eastern outcrop area, a highly faulted terrane in north-east Peary Land, a dolomite-sandstone succession is referred to two formations of the Brønlund Fjord Group. The Ryder Gletscher Group is a thick succession of shallow-water, platform interior carbonates and siliciclastics that extends throughout North Greenland and ranges in age from latest Early Cambrian to Middle Ordovician. The Cambrian portion of this group between Warming Land and south-west Peary Land is formally subdivided into four formations.The Lower Palaeozoic Franklinian Basin is extensively exposed in northern Greenland and the Canadian Arctic Islands. For much of the early Palaeozoic, the basin consisted of a southern shelf, bordering the craton, and a northern deep-water trough; the boundary between the shelf and the trough shifted southwards with time. In North Greenland, the evolution of the shelf during the Cambrian is recorded by the Skagen Group, the Portfjeld and Buen Formations and the Brønlund Fjord, Tavsens Iskappe and Ryder Gletscher Groups; the lithostratigraphy of these last three groups forms the main focus of this paper. The Skagen Group, a mixed carbonate-siliciclastic shelf succession of earliest Cambrian age was deposited prior to the development of a deep-water trough. The succeeding Portfjeld Formation represents an extensive shallow-water carbonate platform that covered much of the shelf; marked differentiation of the shelf and trough occurred at this time. Following exposure and karstification of this platform, the shelf was progressively transgressed and the siliciclastics of the Buen Formation were deposited. From the late Early Cambrian to the Early Ordovician, the shelf showed a terraced profile, with a flat-topped shallow-water carbonate platform in the south passing northwards via a carbonate slope apron into a deeper-water outer shelf region. The evolution of this platform and outer shelf system is recorded by the Brønlund Fjord, Tavsens Iskappe and Ryder Gletscher Groups. The dolomites, limestones and subordinate siliciclastics of the Brønlund Fjord and Tavsens Iskappe Groups represent platform margin to deep outer shelf environments. These groups are recognised in three discrete outcrop belts - the southern, northern and eastern outcrop belts. In the southern outcrop belt, from Warming Land to south-east Peary Land, the Brønlund Fjord Group (Lower-Middle Cambrian) is subdivided into eight formations while the Tavsens Iskappe Group (Middle Cambrian - lowermost Ordovician) comprises six formations. In the northern outcrop belt, from northern Nyeboe Land to north-west Peary Land, the Brønlund Fjord Group consists of two formations both defined in the southern outcrop belt, whereas a single formation makes up the Tavsens Iskappe Group. In the eastern outcrop area, a highly faulted terrane in north-east Peary Land, a dolomite-sandstone succession is referred to two formations of the Brønlund Fjord Group. The Ryder Gletscher Group is a thick succession of shallow-water, platform interior carbonates and siliciclastics that extends throughout North Greenland and ranges in age from latest Early Cambrian to Middle Ordovician. The Cambrian portion of this group between Warming Land and south-west Peary Land is formally subdivided into four formations.

The Late Ordovician Dawson Point Formation (Timiskaming outlier, Ontario): key to a new regional synthesis of Richmondian–Hirnantian carbonate and siliciclastic magnafacies across the central Canadian craton

2007 ◽  
Vol 44 (9) ◽  
pp. 1313-1331 ◽  
Author(s):  
George R Dix ◽  
Mario Coniglio ◽  
John FV Riva ◽  
Aïcha Achab
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Carbonate Platform ◽  
Late Ordovician ◽  
Foreland Basins ◽  
Southern Ontario ◽  
Regional Tectonic ◽  
History Of ◽  
Water Carbonate ◽  
Shallow Water Carbonate

Current paleogeographic reconstructions extend Late Ordovician Taconic-derived siliciclastics across the central Canadian craton prior to the terminal Ordovician glacioeustatic lowstand. Revision of the Late Ordovician Dawson Point Formation of the Timiskaming outlier greatly reduces the distribution of these siliciclastics, and documents a greater spread of shallow-water carbonate of Richmondian age. As revised, the Dawson Point Formation contains two informal members: a deep-water graptolitic shale that grades upward into shallow-water siliciclastic redbeds, and an upper member of shallow-water, muddy, crinoidal limestone with interbedded shale, likely representing low-energy shoals on a muddy shelf. Deep-water shale accumulation began in the upper manitoulinensis graptolite Zone following foundering of the regional foreland carbonate platform. Basin development documents a northward-younging (~1 million years) from southern Ontario foreland basins, in keeping with regional tectonic-driven transgression along eastern North America. The shale-to-carbonate succession of the Dawson Point Formation correlates with the Georgian Bay Formation on Manitoulin Island, wherein the upper carbonate-dominated divisions of both formations are equivalent to the siliciclastic Queenston Formation of southern Ontario. In absence of additional biostratigraphic information, the upper member of the Dawson Point Formation is likely Richmondian (or late Ashgillian) in age. The revised Late Ordovician history of the Timiskaming outlier may identify a once significant volume of shallow-water carbonate across the central Canadian craton, with related sequestration of carbon dioxide possibly aiding global cooling. Erosion of the carbonate, driven by developing glacioeustatic lowstand conditions, was likely contemporaneous with early Hirnantian peritidal deposition of the uppermost Queenston Formation in southern Ontario.

Upper Permian silicified sponges from central Guangxi and western Hubei, South China

1995 ◽  
Vol 69 (2) ◽  
pp. 232-250 ◽  
Author(s):  
J. Keith Rigby ◽  
Fan Jiasong ◽  
Han Nairen
Keyword(s):  
New Species ◽  
Shallow Water ◽  
South China ◽  
Carbonate Platform ◽  
Upper Permian ◽  
Changxing Formation ◽  
Western Hubei ◽  
The Village ◽  
Water Carbonate ◽  
Shallow Water Carbonate

Well-preserved silicified sponges have been recovered from the Upper Permian Changxing Formation at Huangnitang in western Hubei province. The new species Cystauletes grossa and Cystothalamia irregulara are associated with Cystothalamia sp., Colospongia salinaria irregularis Zhang, 1983, Sollasia ostiolata Steinmann, 1882, Virgola? osiensis (de Gregorio, 1930), a questionable inozoan species, and a form questionably referred to the genus Hikorodium? sp. These sponges were detrital fragments that accumulated at the toe of the forereef, at the margin of slope fades and basin fades, at Huangnitang. Amblysiphonella vesiculosa minima Zhang, 1983, is represented in the collections from the Upper Permian Heshan Formation at the village of Guwu, near Heshan City in central Guangxi. Heshan beds that produced the silicified sponges are of Wujiapingian age and accumulated on a normal-marine, shallow-water carbonate platform, or in skeletal shoals within the carbonate platform, and represent a level-bottom community.

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