Early Givetian Research Articles

REVISION OFTENTICOSPIRIFERTIEN, 1938, AND SIMILAR SPIRIFERID BRACHIOPOD GENERA FROM THE LATE DEVONIAN (FRASNIAN) OF EURASIA, NORTH AMERICA, AND AUSTRALIA

The cyrtospiriferid brachiopod genus Tenticospirifer Tien, 1938, is revised based on restudy of the type species from the Frasnian (Late Devonian) of the Russian Platform. As revised the genus includes cyrtospiriferid species with pyramidal ventral valves, catacline ventral interareas, a narrow delthyrium, few sinal plications, and lack a median dorsal septum and pseudodeltidium. All species retained in the genus are of Givetian and Frasnian age. All Famennian age species described from South China and North America are rejected from the genus. It appears that Tenticospirifer evolved during the early Givetian in western Europe and remained endemic to that region during the remainder of the Givetian. Successive migrations of Tenticospirifer from eastern Laurussia to North America, then to South China and possibly Australia, coincided with middle and late Frasnian eustatic sea level rises, respectively. The North American species Spirifera cyrtinaformis Hall and Whitfield, 1872, and related species identified as Tenticospirifer by North American workers, are reassigned to Conispirifer Lyashenko, 1985. Its immigration to and widespread dispersal in carbonate platforms of western Laurussia, northern Gondwana and tropical island arcs (?) coincided with a major late Frasnian eustatic sea level rise. The new family Conispiriferidae is proposed with Conispirifer Lyashenko, 1985, selected as the type genus. The new family also includes the new genus Pyramidaspirifer with Platyrachella alta Fenton and Fenton, 1924, proposed as the type species. The affinity of the new family remains uncertain pending restudy of key genera currently included in the Superfamily Cyrtospiriferoidea. Available data from the Devonian brachiopod literature indicate that species of Pyramidaspirifer are restricted to late Frasnian deposits of central and western North America.

Revision ofTenticospiriferTien, 1938, and similar spiriferid brachiopod genera from the Late Devonian (Frasnian) of Eurasia, North America, and Australia

The cyrtospiriferid brachiopod genusTenticospiriferTien, 1938, is revised based on restudy of the type species from the Frasnian (Late Devonian) of the Russian Platform. As revised the genus includes cyrtospiriferid species with pyramidal ventral valves, catacline ventral interareas, a narrow delthyrium, few sinal plications, and lack a median dorsal septum and pseudodeltidium. All species retained in the genus are of Givetian and Frasnian age. All Famennian age species described from South China and North America are rejected from the genus. It appears thatTenticospiriferevolved during the early Givetian in western Europe and remained endemic to that region during the remainder of the Givetian. Successive migrations ofTenticospiriferfrom eastern Laurussia to North America, then to South China and possibly Australia, coincided with middle and late Frasnian eustatic sea level rises, respectively. The North American speciesSpirifera cyrtinaformisHall and Whitfield, 1872, and related species identified asTenticospiriferby North American workers, are reassigned toConispiriferLyashenko, 1985. Its immigration to and widespread dispersal in carbonate platforms of western Laurussia, northern Gondwana and tropical island arcs (?) coincided with a major late Frasnian eustatic sea level rise. The new family Conispiriferidae is proposed withConispiriferLyashenko, 1985, selected as the type genus. The new family also includes the new genusPyramidaspiriferwithPlatyrachella altaFenton and Fenton, 1924, proposed as the type species. The affinity of the new family remains uncertain pending restudy of key genera currently included in the Superfamily Cyrtospiriferoidea. Available data from the Devonian brachiopod literature indicate that species ofPyramidaspiriferare restricted to late Frasnian deposits of central and western North America.

Revised age of the Mały Bożków limestone in the Kłodzko metamorphic unit (early Givetian, late Middle Devonian) implications for the geology of the Sudetes, SW Poland

Revised age of the Mały Bożków limestone in the Kłodzko metamorphic unit (early Givetian, late Middle Devonian) implications for the geology of the Sudetes, SW Poland

Geniculigypa, a new gypidulid (Brachiopoda) genus from the Middle Devonian of Michigan

A new genus, Geniculigypa, and a new subfamily, the Geniculigypinae, are established. Both taxa are monotypic and have as their type species, Sieberella newtonensis Imbrie, 1959, from the Newton Creek Limestone (early Givetian) of Michigan. This species dramatically differs from all other known gypiduloid species in its possession of a prominent geniculation in both valves and by its radially grooved micro-ornament.

Remnants of Paleozoic cover on the Archean Canadian Shield: Limestone xenoliths from kimberlite in the central Slave craton

Research Article| May 01, 1998 Remnants of Paleozoic cover on the Archean Canadian Shield: Limestone xenoliths from kimberlite in the central Slave craton Harrison O. Cookenboo; Harrison O. Cookenboo 1Canamera Geological Ltd., 399 Mountain Highway, North Vancouver, British Columbia V7J 2K9, Canada Search for other works by this author on: GSW Google Scholar Michael J. Orchard; Michael J. Orchard 2Geological Survey of Canada, 101-605 Robson Street, Vancouver, British Columbia V6B 5J3, Canada Search for other works by this author on: GSW Google Scholar David K. Daoud David K. Daoud 1Canamera Geological Ltd., 399 Mountain Highway, North Vancouver, British Columbia V7J 2K9, Canada Search for other works by this author on: GSW Google Scholar Geology (1998) 26 (5): 391–394. https://doi.org/10.1130/0091-7613(1998)026<0391:ROPCOT>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Harrison O. Cookenboo, Michael J. Orchard, David K. Daoud; Remnants of Paleozoic cover on the Archean Canadian Shield: Limestone xenoliths from kimberlite in the central Slave craton. Geology 1998;; 26 (5): 391–394. doi: https://doi.org/10.1130/0091-7613(1998)026<0391:ROPCOT>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Paleozoic limestone xenoliths have been recovered from kimberlite pipes that intrude the Archean Canadian Shield. Xenoliths from the Jericho pipe in the central Slave craton are commonly fossiliferous and contain a diverse macrofauna and microfauna, including conodonts. Most of the 21 conodont collections that have been recovered are Middle Devonian in age (late Eifelian to early Givetian, and early to middle Givetian). In general, the fauna is indicative of deposition in shallow- and open-marine environments; a few collections are indicative of slightly restricted shoal-shelf seas. A few low-diversity conodont suites could be pre-Middle Devonian. The nearest similar Paleozoic rocks are more than 400 km to the southwest of the Jericho pipe in the foothills of the Mackenzie Mountains. The Jericho limestone xenoliths provide the only solid evidence that shallow Middle Devonian seas inundated the now-exposed Slave craton of the Canadian Shield. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The World's Most Spectacular Carbonate Mud Mounds (Middle Devonian, Algerian Sahara)

ABSTRACT In the southern Ahnet Basin of Algeria a unique Middle Devonian underwater scenery is revealed, which consists of 191 mud mounds, 15 mud ridges, and 2 mud atolls distributed over nine discrete areas of a shallow-pelagic carbonate shelf. All the buildups are totally exhumed, thus perfectly exhibiting their original morphologies, slope angles, elevations, and the pattern of the onlapping strata as well as their relationship to the surrounding off-buildup sequences. Types of buildups include (1) small mud mounds (1-5 m high, 10-20 m diameter), (2) large mud mounds (up to 40 m high, up to 200 m diameter), (3) lens-shaped mounds(1-30 m thick, 10-15° slopes), (4) mud ridges (up to 100 m high, 150-8500 m long) and (5) semicircular mud atolls (2500-2800 m long, 20-30 m high). The buil ups were constructed during a short time span in the early Givetian (part of the Lower varcus zone), probably not exceeding a few hundred thousand years. Sedimentation rates in coeval off-buildup areas were at least 3-10 times lower. The lithology of the buildups is a massive boundstone with a high proportion of irregular, spar-filled cavities (stromatactis) but only very scattered potential frame builders. The carbonate mud is considered to be an in situ, cyanobacterial precipitate, although evidence of such is poor. Organic components of the buildups are not significantly different from those of the off-buildup lithologies, and include numerous crinoid ossicles, some tabulate and solitary rugose corals, brachiopods, mollusc debris, trilobites, and very rare sponge spicule and bryozoans. The total absence of stromatoporoids, large tabulate and colonial rugose corals, green algae, and micritic envelopes around grains suggests growth of the buildups in the lower part of the photic zone (100-200 m). They are onlapped by a discontinuous sequence, a few meters thick, of skeletal packstones and grainstones, and locally, orthoceratid floatstones that were deposited later in the Givetian. A widespread rise of sea level in the early Frasnian buried both buildups and adjacent areas under shales and siltstones. Postdepositional alteration of the mud buildups includes: (1) formation of stromatactis cavities, probably by dewatering and internal erosion, (2) cementation of stromatactis cavities and interparticle pore spaces by early high-Mg calcite and late, blocky low Mg calcite, (3) neomorphic transformation of Mg-calcitic mud and aragonitic skeletal debris, (4) occasional formation of neptunian dikes, (5) slight erosion of buildup surfaces, (6) compaction and slumping of onlapping capping beds, and (7) local dolomitization. The formation and growth of the mud build-ups is envisaged as a sequence of stages starting with patchy coral thickets evolving into small mud mounds that coalesced into larger mounds. By continuous vertical and lateral growth, closely spaced mounds amalgamated into mud ridges and mud atolls. Regular NW-SE and N-S patterns of some mound rows and ridges show a relationship of buildup formation to rejuvenated late Precambrian tectonic lineaments, which reappear in the Hercynian orogeny. The isotopic signature of matrix and early ements of mound rocks, however, does not support the idea of fluid migration and hydrothermal CO2 supply during buildup growth.

West Gondwanan aspects of the Middle and Upper Devonian miospore zonation in North Africa and Brazil

The stratigraphical distribution of 11 miospore species found so far only in North Africa and Brazil are compared to the range of taxa which characterize the west European based zonation in order to establish accurate determinations. The zonate-camerate miospores that are more or less restricted to the Middle Devonian are the most frequent. Other taxa, often camerate with some tabulate ornamentation, first occur near the Givetian-Frasnian boundary. Three of them are restricted to Brazil. These species are more abundant in the early Givetian. During the late Givetian they are probably more numerous in North Africa than in Brazil. Their relative frequencies strongly decrease during the Frasnian. A greater climatic contrast between the two regions during the late Eifelian (?) and the late Givetian and Frasnian than during the early Givetian is inferred.

Steep-sided carbonate mud mounds in the Middle Devonian of the eastern Anti-Atlas, Morocco

AbstractDuring the Eifelian and early Givetian, isolated mud mounds were established in a shallow basin, predominantly characterized by calcareous mudstone deposition, in the eastern Anti-Atlas of Morocco. The shapes, lithologies and faunas of these mounds stand in marked contrast with those of nearby contemporaneous, more widespread stromatoporoid/coral biostromes and small carbonate platforms adjacent to shallow shelves. With one exception, the mounds are totally exhumed, perfectly exposing their original morphologies. The smaller mounds are asymmetrical, with steeper northeastern and eastern (35–75°) than southwestern and western flanks (30–50°). The largest mound is almost circular and symmetrical, with scattered stromatoporoids, tabulate and rugose corals that do not form a rigid framework. Frame-builders are much rarer or absent in the smaller mounds. The nature and geographical distribution of the mounds reflects a bathymetric gradient, indicating that they formed on low-angle ramps which sloped gently into a shallow basin. A large reef mound was constructed at moderate depth, while small mud mounds accumulated in deeper water. Decrease of frame-builders and increase in pelagic organisms in the latter document the transition to a pelagic platform with reduced sedimentation at a short distance from the deepest mound.

Chitinozoaires du genre Alpenachitina dans le Dévonien moyen du Brésil; Intérêt stratigraphique et relations phylogénétiques

Subsurface samples from the Paraná basin (southern Brasil)have yielded abundant and well preserved Chitinozoa. Two new taxa, Alpenachitina matogrossensis sp. nov. and A. petrovinensis sp. nov. are described and illustrated. In the lower part of the borehole, in strata corresponding to the Early Givetian, the latter succeeds to the former and both coexist with Alpenachitina eisenacki Dunn & Miller, 1964 . The phylogenetic relationship of these three taxa are discussed.

New occurrences of color patterns in Devonian articulate brachiopods

Significant new occurrences of Devonian articulate brachiopods retaining color patterns includingStringocephalus burtiniDefrance from the Givetian of southern England with both concentric and radial bands, an undetermined stringocephalid brachiopod with concentric bands from the Givetian of the western Brooks Range, Alaska,Beachiacf.B. thunii(Clarke) from the mid-Early Devonian Oriskany Sandstone of Schoharie, New York, with a prominent pair of radial color bands, andAthyris vittataHall from the early Givetian Ferron Point Formation of Michigan with numerous radial color bands are illustrated. The presence of preserved color patterns is documented for the first time in members of the family Stringocephalidae King and in the family Athyrididae McCoy.

New occurrences of color patterns in Devonian articulate brachiopods

Significant new occurrences of Devonian articulate brachiopods retaining color patterns includingStringocephalus burtiniDefrance from the Givetian of southern England with both concentric and radial bands, an undetermined stringocephalid brachiopod with concentric bands from the Givetian of the western Brooks Range, Alaska,Beachiacf.B. thunii(Clarke) from the mid-Early Devonian Oriskany Sandstone of Schoharie, New York, with a prominent pair of radial color bands, andAthyris vittataHall from the early Givetian Ferron Point Formation of Michigan with numerous radial color bands are illustrated. The presence of preserved color patterns is documented for the first time in members of the family Stringocephalidae King and in the family Athyrididae McCoy.

Devonian miospores from Papa Stour, Shetland

ABSTRACTDevonian miospores have been discovered in the previously poorly dated Old Red Sandstone volcanic sequence of Papa Stour. They occur at two sites in minor sedimentary deposits between the lavas, and fossil fish remains are also present. The age range of the miospores is mid Eifelian to early Givetian, probably more specifically late Eifelian and from a position close to the Achanarras horizon. This allows a correlation of the Papa Stour volcanic sequence with that of the Upper Stromness Flags of Orkney and not the tuffaceous horizons in the Eday Sandstones. The good preservation and composition of the miospores indicate a close similarity to other Orcadian Basin sediments and support the view that the Old Red Sandstone sequences W of the Melby Fault have affinities with the Orkney and Caithness successions rather than with Shetland. The age of the volcanic sequence also provides a valuable datum point for plate tectonic models based on the geochemistry of Old Red Sandstone lavas.

Distribution of Tylothyris (Brachiopoda) and its occurrence in the Traverse Group (Middle Devonian) of Michigan

The septate, lamellose, spiriferacean brachiopod genus Tylothyris North, 1920, is considered to be a delthyridid of the subfamily Tylothyridinae Carter, 1972. Herein, the diagnosis of the Tylothyridinae is emended to include forms with micro-ornament, and with a myophragm or median septum on the floor of the pedicle valve.For the first time, Tylothyris is formally reported from the Traverse Group rocks of Michigan, Givetian through early Frasnian in age. Two species of the genus occur in the Traverse Group. The first, T. subvaricosa (Hall and Whitfield, 1872), previously described by Stainbrook (1943) from the Cedar Valley Limestone of Iowa, is also known from the Milwaukee Formation of Wisconsin and the Mineola Limestone of Missouri. Tylothyris randalia Stainbrook, 1943, also from the Cedar Valley Limestone, is considered to be synonymous with T. subvaricosa. In the Traverse Group, T. subvaricosa occurs in the Bell Shale, Rockport Quarry Limestone, Ferron Point Formation, Genshaw Formation, Alpena Limestone, Gravel Point Formation, Norway Point Formation, and Potter Farm Formation. The second species, T. rockportensis n. sp., occurs only in the Rockport Quarry Limestone, and appears to be endemic to the Michigan Basin.Tylothyris is considered to have originated in the Illinois area during the late Eifelian, then to have migrated to the Michigan area by the early Givetian. With the onset of Taghanic Onlap during the late Givetian, the genus dispersed from its Illinois–Michigan area of origin, becoming distributed across much of North America during the Frasnian and Famennian, and becoming essentially cosmopolitan in distribution during the Tournaisian. Tylothyris apparently became extinct by the end of the Visean.

Sur la présence de Palaeomicrocodium (Algue?, Incertae sedis?) dans le Givétien inférieur de Belgique

Describes the oldest recorded microcodiacean fromthe Early Givetian Alvaux Limestone (Namur Syncline, Belgium). Palaeomicrocodium devonicum Mamet & Roux characterizes very shallow water carbonates associated with Sphaerocodium mudmounds. Cenozoic contamination is excluded.

A new genus of lycopods from the Devonian of New York State

Drepanophycus colophyllus Grierson & Banks is transferred to llaskinsia Grierson & Banks on the basis of the morphology of its leaves and its anatomical structure. Slender, dichotomizing axes bear helically arranged leaves that are falcate, petiolate, simple, lanceolate and entire. A solid cylinder of metaxylem is surrounded by ridges of protoxylem. Pitting on tracheid walls is annular, helical, reticulate, scalariform to circular-bordered. This lycopod extends from early Givetian into early Frasnian time in the Catskill strata of eastern New York State. The effect of cleavage of fossiliferous rock on patterns observed on the exposed fossils and the bearing of recent research on the fossil history of lycopods are discussed.

Ordovician to Devonian History of Northern Yukon and Adjacent District of Mackenzie

ABSTRACT The eastern half of the study area, the Mackenzie and Anderson River Plains area, is underlain by uniform sequences of carbonates and relatively minor shales, cherts and evaporites, and is marked by widespread, regional disconformities. Middle Ordovician, Upper Silurian, and at least the lower Lower Devonian sediments are completely absent from the area. The western portion that is, roughly the northern part of Yukon -- was, as a result of more local tectonic instability, characterized by more rapid facies changes, development of troughs, ridges and basins, and more localized disconformities and unconformities. The Richardson Trough, more or less conforming in outline to the area of the present Richardson Mountains, was a deeper-water, graptolite-shale trough from before earliest Ordovician through to at least early Emsian; was apparently positive between late Emsian and early Givetian; and, finally, was an area of rapid sedimentation throughout the remaining Devonian. South of but in linear continuity with the Richardson Trough, a structure recognized for the first time and termed the Bonnet Plume High may have been emergent throughout the Ordovician, Silurian and the earliest part, at least, of the Devonian. The area west of the present Richardson Mountains, north of the Ogilvie Mountains, and south of British and Barn Mountains, and termed the Yukon Stable Block, was one of platform-carbonate deposition. The Block was more or less diagonally dissected by an essentially NE-SW-trending structure, the Dave Lord High, which was positive from Late Ordovician through to at least mid-Early Devonian times. At times what was probably a subaqueous extension of this High joined with an area of carbonate development west of and beneath the Mackenzie River delta, and appears to have restricted the northern end of the Richardson Trough. The Neruokpuk Formation of the British Mountains, in the extreme northwestern portion of the region, is considered to be at least Early Ordovician to Late Silurian in age, because of correlation with rocks of the same formation in Alaska, and because of its lithologic similarity to rocks of that age range in the Barn Mountains. These rocks are interpreted as miogeosynclinal equivalents of the more stable platform suites to the south and southeast. Intrusion of two small, granitic masses is believed to have occurred at about Early Devonian time in the Barn Mountains area. End_Page 321------------------------ During late Middle and early Late Devonian times, the sedimentation pattern of the entire region changed, leading to the deposition of black, siliceous shale and localized reefs. This was followed during later Frasnian and Famennian time by strong uplifting in and northwest of the British and Barn Mountains regions, and the deposition of widespread and locally great thicknesses of clastic sediments to the southeast. These are characterized by coarse, greywacke-type sediments in the northwest, grading southeastward to finer sandstones and siltstones, and minor carbonates.