Beyond Beecher's Trilobite Bed: Widespread pyritization of soft tissues in the Late Ordovician Taconic foreland basin

Geology ◽  
2009 ◽  
Vol 37 (10) ◽  
pp. 907-910 ◽  
Author(s):  
Úna C. Farrell ◽  
Markus J. Martin ◽  
James W. Hagadorn ◽  
Thomas Whiteley ◽  
Derek E.G. Briggs
Keyword(s):  
Soft Tissues ◽  
Foreland Basin ◽  
Late Ordovician

An enigmatic blastozoan echinoderm fauna from central kentucky

2009 ◽  
Vol 83 (5) ◽  
pp. 739-749 ◽  
Author(s):  
Colin D. Sumrall ◽  
Carlton E. Brett ◽  
Troy A. Dexter ◽  
Alexander Bartholomew
Keyword(s):  
North America ◽  
Northwest Territories ◽  
Middle Devonian ◽  
Fossil Record ◽  
Foreland Basin ◽  
Late Ordovician ◽  
Upper Devonian ◽  
Range Extension ◽  
First Report ◽  
Appalachian Foreland

A series of small road cuts of lower Boyle Formation (Middle Devonian: Givetian) near Waco, Kentucky, has produced numerous specimens of three blastozoan clades, including both “anachronistic” diploporan and rhombiferan “cystoids” and relatively advanced Granatocrinid blastoids. This unusual assemblage occurs within a basal grainstone unit of the Boyle Limestone, apparently recording a local shoal deposit. Diploporans, the most abundant articulated echinoderms, are represented by a new protocrinitid species, Tristomiocystis globosus n. gen. and sp. Glyptocystitoid rhombiferans are represented by isolated thecal plates assignable to Callocystitidae. Three species of blastoids, all previously undescribed, include numerous thecae of the schizoblastid Hydroblastus hendyi n. gen. and sp., the rare nucleocrinid Nucleocrinus bosei n. sp., and an enigmatic troosticrinid radial. The blastoid Nucleocrinus is typical for the age; however, the callocystitid, schizoblastid, and protocrinitid are not. Hydroblastus is the oldest known schizoblastid. Middle and Upper Devonian callocystitids have been previously reported only from Iowa and Michigan USA with unpublished reports from Missouri USA and the Northwest Territories, Canada. This occurrence is thus the first report of a Middle Devonian rhombiferan from the Appalachian foreland basin. Tristomiocystis is the first known protocrinitid in North America and the only protocrinitid younger than Late Ordovician. This occurrence thus represents a range extension of nearly 50 million years for protocrinids. This extraordinary sample of echinoderms in a Middle Devonian limestone from a well-studied area of North America highlights the incompleteness of the known fossil record, at least in fragile organisms such as echinoderms.

Taconian mélanges in the parautochthonous zone of the Quebec Appalachians revisited: implications for foreland basin and thrust belt evolution

2004 ◽  
Vol 41 (12) ◽  
pp. 1473-1490 ◽  
Author(s):  
F -A Comeau ◽  
D Kirkwood ◽  
M Malo ◽  
E Asselin ◽  
R Bertrand
Keyword(s):  
Foreland Basin ◽  
Late Ordovician ◽  
Thrust Faults ◽  
Thrust Belt ◽  
Thrust Sheet ◽  
Utica Shale ◽  
Thermal Maturation ◽  
Early Late

In the Quebec Appalachians, disruption, imbrication, and thrusting of the Taconian foreland basin sequence are responsible for the development of chaotic units within the turbiditic sequence of the Caradocian Sainte-Rosalie Group, the main lithologic assemblage of the parautochthonous zone. These chaotic units have been termed olistostromes or tectonosomes on the basis of field criteria and following Pini's (1999) classification. Olistostromal units containing blocks of the middle mudstone (Utica Shale) and upper turbidite units (Ste-Rosalie Group) of the foreland basin and spanning the Caradocian N. gracilis, C. americanus, O. ruedemanni, and C. spiniferus graptolite zones were deposited and incorporated into the Sainte-Rosalie Group. Disruption of more competent beds of the flyschic sequence and fault stacking and slicing of older rock units occurred along major thrust faults and now form structurally aligned corridors or tectonosomes. Graptolites and new chitinozoan data from both olistostromes and tectonosomes indicate older ages (early Late Ordovician) than the flysch units of Sainte-Rosalie Group (mid Late Ordovocian). Lithological, stratigraphic, and structural criteria indicate that tectonosome slices are imbricated foreland basin rocks that are correlative to the Black River, Trenton, Utica, Sainte-Rosalie, and Lorraine groups of the Laurentian platform. Thermal maturation data indicates that disruption of the autochthonous sequence, and folding and thrusting of the entire foreland basin sequence, must have occurred shortly after their deposition. Contrary to what had been suggested, blocks in the olistostromes and tectonosomes were not derived from the allochthonous Chaudière thrust sheet, even though it presently marks the southern contact with the parautochthonous zone. Imbrication of the foreland basin sequence must have occurred before emplacement of the Chaudière thrust sheet.

Basin development and inversion at the Appalachian structural front, Port au Port Peninsula, western Newfoundland Appalachians

1993 ◽  
Vol 30 (9) ◽  
pp. 1759-1772 ◽  
Author(s):  
John W. F. Waldron ◽  
Glen S. Stockmal ◽  
Randolph E. Corney ◽  
Sheila R. Stenzel
Keyword(s):  
Foreland Basin ◽  
Fault Scarp ◽  
Late Ordovician ◽  
The West ◽  
Western Basin ◽  
Middle Ordovician ◽  
Platform Carbonates ◽  
Palinspastic Restoration ◽  
And Inversion ◽  
Basin Boundaries

In the Humber Zone of the Newfoundland Appalachians, Cambro-Ordovician shelf and foreland basin successions are affected by Middle Ordovician (Taconian orogeny) and Devonian (Acadian orogeny) deformation. On Port au Port Peninsula the presence of the Late Ordovician to Late Silurian Long Point – Clam Bank succession allows these episodes to be separated. The Taconian foreland basin stratigraphy on Port au Port Peninsula is highly variable. On the west coast, platform carbonates are overlain by megaconglomerates of the Cape Cormorant Formation, which record progressive exposure of 1 km of the platform succession. The conglomerates are restricted to a narrow zone, consistent with derivation from a fault scarp originally immediately west of the outcrops (in palinspastic restoration). Farther east, at Victors Brook, the Cape Cormorant Formation is absent, but the overlying, almost undeformed Goose Tickle Group contains conglomerate derived both from the upper part of the platform succession and from the Taconian Humber Arm Allochthon. Southeast of Victors Brook, the top of the platform is overlain directly by scaly shales and mélange of the Humber Arm Allochthon, which includes deformed equivalents of the foreland basin succession. The distribution of conglomeratic units, the presence and configuration of faults, and the preservation of the Goose Tickle Group in the Victors Brook area imply that a fault-bounded basin developed in advance of the Humber Arm Allochthon during the Taconian orogeny. This basin is interpreted to have resulted from flexural extension of North American lithosphere. The close spatial coincidence between later Acadian structures and the Taconian basin boundaries implies that the basin-bounding faults were reactivated as thrusts and reverse faults, and that the basin underwent inversion during Acadian thrusting. The western basin-bounding fault, modified by the development of a "short cut" thrust, developed into the present-day Round Head thrust.

Parallel geological development in the Dunnage Zone of Newfoundland and the Lower Palaeozoic terranes of southern Scotland: an assessment

1992 ◽  
Vol 83 (3) ◽  
pp. 571-594 ◽  
Author(s):  
S. P. Colman-Sadd ◽  
P. Stone ◽  
H. S. Swinden ◽  
R. P. Barnes
Keyword(s):  
Volcanic Rocks ◽  
Foreland Basin ◽  
Late Ordovician ◽  
Marine Transgression ◽  
Early Ordovician ◽  
Sedimentary Sequences ◽  
Structural Regime ◽  
Lower Palaeozoic ◽  
Back Arc ◽  
Combined Data

AbstractThe Notre Dame and Exploits subzones of Newfoundland's Dunnage Zone are correlated with the Midland Valley and Southern Uplands of Scotland, using detailed comparisons of two key Lower Palaeozoic successions which record similar histories of extension and compression. It follows that the Baie Verte Line, Red Indian Line and Dover Fault are equivalent to the Highland Boundary Fault, Southern Upland Fault and Solway Line, respectively.The Betts Cove Complex and overlying Snooks Arm Group of the Notre Dame Subzone are analogous to the Ballantrae Complex of the Midland Valley, both recording the Arenig evolution and subsequent obduction of an arc and back-arc system. The Early Ordovician to Silurian sequence unconformably overlying the Ballantrae Complex is poorly represented in the Notre Dame Subzone but important similarities can still be detected suggesting corresponding histories of continental margin subsidence and marine transgression.In the Exploits Subzone, Early Ordovician back-arc volcanic rocks are overlain by Llandeilo mudstones and Late Ordovician to Early Silurian turbidites. A similar stratigraphy occurs in the Northern and Central Belts of the Southern Uplands and both areas have matching transpressive structural histories. Deeper erosion in the Exploits Subzone reveals Cambrian and Early Ordovician volcano-sedimentary sequences structurally emplaced on the Gander Zone, and such rocks are probably present beneath the Southern Uplands. Combined data from the Notre Dame Subzone and Midland Valley suggest an Arenig southeast-dipping subduction zone. Early Ordovician volcanic rocks in the Exploits Subzone and Southern Uplands have back-arc basin geochemistry and support the model of the Southern Uplands as a transition from back-arc to foreland basin. Preferential emergence of the Dunnage Zone and contrasts between Exploits Subzone and Southern Uplands turbidite basins are attributed to collision of Newfoundland with a Laurentian promontory and Scotland with a re-entrant. This hypothesis also explains the transpressive structural regime common to both areas.

Mid-Paleozoic thrusting at the Appalachian deformation front: Port au Port Peninsula, western Newfoundland

1991 ◽  
Vol 28 (12) ◽  
pp. 1992-2002 ◽  
Author(s):  
John W. F. Waldron ◽  
Glen S. Stockmal
Keyword(s):  
Carbonate Platform ◽  
Foreland Basin ◽  
Late Ordovician ◽  
Western Boundary ◽  
Seismic Profiles ◽  
The West ◽  
Deformation Front ◽  
Middle Ordovician ◽  
Triangle Zone ◽  
Map Scale

Structures exposed on Port au Port Peninsula in western Newfoundland record the nature of the Appalachian deformation front, which forms the western boundary of the Humber tectono-stratigraphic zone. The major structures affect the Late Ordovician to Late Silurian Long Point – Clam Bank succession, but not the unconformably overlying Carboniferous rocks; they are probably of Devonian age.At the west coast of the peninsula, Long Point and Clam Bank strata are affected by both east-vergent and west-vergent structures. The basal surface of the succession is interpreted as an east-vergent thrust, forming the upper detachment of a "triangle zone," and correlates with a similarly located contact seen in offshore multichannel seismic profiles. Within the succession, east-vergent deformation zones locally duplicate the stratigraphy. West-vergent structures, including a map-scale overturned fold north of Round Head mountain, are probably younger.Farther south, Middle Ordovician foreland basin sediments are also affected by east-vergent thrusts, which have been variably rotated by west-vergent folds. In the underlying Cambrian–Ordovician platform carbonate succession, east-vergent thrusts duplicate the stratigraphy.These structures are related to telescoping of the carbonate platform and the overlying Humber Arm Allochthon during Devonian westward wedging of the structural triangle zone beneath the Long Point – Clam Bank succession. The platform succession must therefore be allochthonous, and the Humber Arm Allochthon has been transported to the west of its Late Ordovician position.

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