Conodonts and corals in kimberlite xenoliths confirm a Devonian seaway in central Ontario and Quebec

2000 ◽  
Vol 37 (12) ◽  
pp. 1651-1663 ◽  
Author(s):  
Alexander D McCracken ◽  
Derek K Armstrong ◽  
Thomas E Bolton
Keyword(s):  
Sedimentary Rock ◽  
Late Ordovician ◽  
Stratigraphic Correlation ◽  
Lake Area ◽  
Early Devonian ◽  
Physical Evidence ◽  
Colour Changes ◽  
Conodont Colour Alteration Index ◽  
Colour Alteration ◽  
Age Determinations

Eighteen samples containing sedimentary rock xenoliths were obtained from cores drilled into eight Mesozoic kimberlite pipes in the Kirkland Lake area, Ontario, and in Ontario and Quebec near Lake Timiskaming. Nine samples from five pipes contained fossils that were used for age determinations. These fossils are Middle or Late Ordovician graptolites, inarticulate brachiopods, and conodonts; Silurian and (or) Devonian conodonts; Early Devonian colonial corals; a Devonian stromatoporoid; and Early to Middle Devonian conodonts. Regionally, conodonts are unaltered (conodont colour alteration index, CAI 1). Conodont CAI values from the xenoliths are elevated (CAI 2), and a few conodonts have surface colour changes, suggesting hydrothermal alteration. Age determinations allow stratigraphic correlation between xenoliths and Paleozoic outcrops. For the Ordovician and Silurian samples, correlations are made to exposures in the nearby Lake Timiskaming outlier. For the Devonian samples, the closest possible correlative outcrops are about 300 km away. These fossils provide the first physical evidence of a connection between a Lake Timiskaming "basin" and other Ontario basins during at least part of the Devonian. These strata persisted at least until the Mesozoic before they were removed by erosion.

Polyphase metamorphism in the eastern Carnic Alps (N Italy–S Austria): clay minerals and conodont Colour Alteration Index evidence

2007 ◽  
Vol 97 (6) ◽  
pp. 1213-1229 ◽  
Author(s):  
Covadonga Brime ◽  
Maria Cristina Perri ◽  
Monica Pondrelli ◽  
Claudia Spalletta ◽  
Corrado Venturini
Keyword(s):  
Clay Minerals ◽  
Carnic Alps ◽  
Conodont Colour Alteration Index ◽  
Polyphase Metamorphism ◽  
Colour Alteration

Early Silurian paleopole for redbeds and volcanics of the King George IV Lake area, Newfoundland

1989 ◽  
Vol 26 (10) ◽  
pp. 1904-1917 ◽  
Author(s):  
K. L. Buchan ◽  
J. P. Hodych
Keyword(s):  
North America ◽  
Late Ordovician ◽  
Paleomagnetic Data ◽  
Atlantic Canada ◽  
Lake Area ◽  
Consistent Direction ◽  
Canadian Appalachians

Redbeds and felsic and mafic volcanics of the King George IV Lake area of the Dunnage Zone in southwestern Newfoundland have been studied paleomagnetically. After unfolding, both hematite and magnetite carry a consistent direction of magnetization (D = 29.6°; I = 1.0°; k = 19.3; α95 = 11.3°) corresponding to a near-equitorial paleolatitude (0.5°N ± 6°) and yielding a paleopole at 84.6°E, 35.9°N (dm = 11.3°; dp = 5.6°). A positive fold test shows that the remanence was acquired before Devonian deformation. A positive conglomerate test and a reversal of the magnetization in a continuous redbed sequence demonstrates that the remanence was acquired at the time of formation, which has been assigned to the Early Silurian on the basis of a U–Pb zircon date of 431 ± 5 Ma.No other undisputed primary or pre-fold remanence has been reported from Atlantic Canada for the Late Ordovician – Silurian period. Therefore, from paleomagnetic data it is not yet possible to estimate the amount of post-Silurian movement within the Canadian Appalachians. Pre-fold magnetizations from Late Ordovician and Silurian rocks of cratonic North America predict a paleolatitude of 16°S ± 12 °for Newfoundland. However, further results are necessary to determine whether any significant displacement has occurred between Newfoundland and the craton since the Early Silurian.

Metamorphic fluids and transtension in the Cantabrian Mountains of northern Spain: an application of the conodont colour alteration index

1986 ◽  
Vol 123 (6) ◽  
pp. 673-681 ◽  
Author(s):  
J. G. M. Raven ◽  
Ben A. Van Der Pluijm
Keyword(s):  
Large Scale ◽  
Fluid Transport ◽  
Spatial Relationship ◽  
Structural Features ◽  
Lower Permian ◽  
Low Grade ◽  
Northern Spain ◽  
Cantabrian Zone ◽  
Conodont Colour Alteration Index ◽  
Colour Alteration

AbstractConodont colour alteration index (CAI) values from Upper Paleozoic rocks in the Cantabrian zone of northern Spain show that temperatures during Hercynian metamorphism locally exceeded 300 °C. Various temperature domains have been defined, which are generally separated by fundamental structures. These domains do not correspond with the tripartite subdivision based on stratigraphic analysis.The observed CAI values of conodonts are in general agreement with the mineral paragenesis. Areas with high CAI values display extensive alteration and mineralization, and where CAI values exceed 4–4.5 (>200 °C) slaty cleavage has developed.The Cantabrian zone is an area of very low grade metamorphism, where peak conditions were reached in Upper Carboniferous to Lower Permian times. The characteristics of the metamorphism and its spatial relationship with major faults suggest that fluids were the main source for regional heating and that fluid transport was focussed along crustal-scale structural features.The overall deformation regime in this part of the Variscan orogen of western Europe is interpreted to be large-scale transtension. This is in agreement with earlier proposed models for the formation of Upper Palaeozoic basins in this area.

The Antrim–Galway Line: a resolution of the Highland Border Fault enigma of the Caledonides of Britain and Ireland

1995 ◽  
Vol 132 (2) ◽  
pp. 171-184 ◽  
Author(s):  
P. D. Ryan ◽  
N. J. Soper ◽  
D. B. Snyder ◽  
R. W. England ◽  
D. H. W. Hutton
Keyword(s):  
Deep Structure ◽  
Sedimentary Basins ◽  
Strike Slip ◽  
Late Ordovician ◽  
Magnetic Data ◽  
The South ◽  
Early Devonian ◽  
Border Fault ◽  
Western Ireland

AbstractThe westward continuation of the Highland Border fault of Scotland (HBFZ) into Ireland is problematic. It is widely thought to follow a pronounced magnetic and gravity lineament, the Fair Head-Clew Bay Line (FCL). The advantage of this interpretation is that it places all the Ordovician ophiolitic complexes and associated sedimentary basins to the south of the FCL, which would represent the contact between Laurentia and the outboard terranes. Its main shortcomings are that both the deep structure and timing of strike-slip are different on the HBFZ and FCL. In Ireland the FCL is a north-dipping feature that can be traced to the Moho on BIRPS profiles, while the HBFZ has no such signature. Terrane amalgamation in western Ireland was completed by the late Ordovician, while in Scotland the Midland Valley terrane did not finally dock until the early Devonian. These considerations suggest that in western Ireland a branch of the HBFZ exists, which was active in post-Ordovician time and must lie south of Connemara. An examination of Irish geological, geophysical and image-processed magnetic data shows that a profound lineament can be traced from Antrim to Galway Bay (the Antrim–Galway Line). Stitching plutons date movement on it as pre-405 Ma. We propose that the Antrim–Galway Line represents the continuation of the Scottish HBFZ, while the FCL is a preserved Ordovician splay of the HBFZ system whose northdipping geometry is a product of Ordovician collapse of the orogen in western Ireland.

The location of the Iapetus Ocean suture in Newfoundland

1977 ◽  
Vol 14 (3) ◽  
pp. 488-495 ◽  
Author(s):  
W. S. McKerrow ◽  
L. R. M. Cocks
Keyword(s):  
Lower Devonian ◽  
New World ◽  
Late Ordovician ◽  
Calc Alkaline ◽  
The West ◽  
Early Devonian ◽  
Iapetus Ocean ◽  
Lower Palaeozoic ◽  
First Time ◽  
Avalon Peninsula

Brachiopod and trilobite faunal distributions indicate that the Iapetus Ocean was still wide enough to inhibit migration in the Middle and Late Ordovician. The presence of Silurian and Lower Devonian calc-alkaline rocks suggests that ocean crust was still being subducted long after the end of the Ordovician and that the Iapetus Ocean did not finally close in Newfoundland until the Acadian Orogeny. The Reach Fault divides successions containing different Lower Palaeozoic faunas; to the west, typical North American faunas occur in New World Island (Cobb's Arm Limestone), while to the east the rocks of the Gander region appear to have been attached to the Avalon Peninsula, with its European Lower Palaeozoic faunas, since the Early Ordovician. It is concluded that the Reach Fault marks the suture where the Iapetus Ocean closed at the end of the Early Devonian. This line probably extends across Newfoundland to the south of Buchans, and links up with the Cape Ray Fault in the southwest of the island. An Ordovician fauna from the Davidsville Group of the Gander area is illustrated for the first time; it is not clearly definitive of any faunal province.

Thermal maturation of the Lower Palaeozoic strata of northern Greenland from conodont colour alteration index (CAI) data: implications for burial history and hydrocarbon exploration

1994 ◽  
Vol 131 (2) ◽  
pp. 219-230 ◽  
Author(s):  
H. A. Armstrong ◽  
M. P. Smith ◽  
R. J. Aldridge ◽  
S. J. Tull
Keyword(s):  
Carbonate Platform ◽  
Hydrocarbon Exploration ◽  
Thermal Maturity ◽  
Burial History ◽  
Thermal Maturation ◽  
The North ◽  
Conodont Colour Alteration Index ◽  
Lower Palaeozoic ◽  
Colour Alteration ◽  
North Greenland

AbstractConodont colour alteration data for the Lower Palaeozoic strata of the North Greenland carbonate platform indicate a pattern of increased thermal maturity northwards within the Franklinian Basin. There is little variation in values through the Canadian–Llandovery (Lower Ordovician–Lower Silurian) interval at any given locality. A simplified thermal model for the platform suggests that the predominant control of conodont colour alteration and thermal maturation was maximum depth of burial, which occurred during the mid- to late Silurian. A preliminary integrated scheme for conodont and organic thermal maturity indicators can be compiled from the data now available from North Greenland.

Late Ordovician–early Silurian destruction of the Iapetus Ocean: Newfoundland, British Isles and Scandinavia—a discussion

1988 ◽  
Vol 79 (4) ◽  
pp. 361-382 ◽  
Author(s):  
Kevin T. Pickering ◽  
Michael G. Bassett ◽  
David J. Siveter
Keyword(s):  
Oceanic Crust ◽  
Mainland China ◽  
Late Ordovician ◽  
Plate Tectonic ◽  
British Isles ◽  
Foreland Basins ◽  
Early Devonian ◽  
Iapetus Ocean

ABSTRACTThe available data from Newfoundland, the British Isles and Scandinavia suggest that by late Ordovician–early Silurian times the ocean separating Laurentia from Eastern Avalonia and Baltica had partly closed with the consumption of intervening oceanic crust. Marine seaways, however, persisted until the middle or late Silurian. Phases of crustal transtension and transpression, predominantly under a major sinistral shear couple, occurred throughout the Silurian and early Devonian until the remnant Iapetus Ocean was completely destroyed. The most appropriate Recent plate tectonic models for Silurian sedimentation between Eastern Avalonia and Laurentia are probably the deep-marine foreland basins between Timor and the northern Australian margin, or between Taiwan and mainland China.

scholarly journals Reservoir quality and K-Ar age dating of the pre-Khuff section of Kuwait

GeoArabia ◽  
2003 ◽  
Vol 8 (4) ◽  
pp. 601-620 ◽  
Author(s):  
Christian J. Strohmenger ◽  
Menahi S. Al-Anzi ◽  
David R. Pevear ◽  
Robert F. Ylagan ◽  
Tobi H. Kosanke ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Gravity Data ◽  
Early Carboniferous ◽  
Late Ordovician ◽  
Age Dating ◽  
Percent Confidence Interval ◽  
Burial Diagenesis ◽  
Thin Sections ◽  
Early Devonian ◽  
Deep Wells

ABSTRACT Based on studies of petrographic thin sections from core and cutting samples, the pre-Permian siliciclastics in four deep wells in southern Kuwait were found to be tight. Three of these wells are located on the crestal region of the Burgan Arch, and one on the Umm Gudair anticline. These clastics were encountered beneath a thin brick-red shale of unknown thickness, immediately below the pre-Khuff unconformity at the base of the Permian-Triassic Khuff Formation. The pre-Khuff clastics range in thickness from a few tens of feet to more than 4,000 ft, and overlie a Proterozoic argillite (Economic Basement). Based on Illite Age Analysis (IAA) of samples from cores, the depositional K-Ar age of the pre-Khuff clastics is estimated to be younger than 509 Ma (90 percent confidence interval: 544–481 Ma, i.e. Cambrian-Early Ordovician). The argillite was uplifted through the 300°C isotherm at about 611 Ma (90% confidence interval: 635-588 Ma, i.e Late Proterozoic); its deposition and metamorphism preceded this date. During the Paleozoic, the pre-Khuff clastics were buried to depths of 10,000–15,000 ft, but were subsequently uplifted in the Late Paleozoic. IAA diagenetic K-Ar ages of the Economic Basement (421 Ma; 90 percent confidence interval: 442-397 Ma; Late Ordovician-Early Devonian) and pre-Khuff clastics (369 Ma; 90 percent confidence interval: 404–337 Ma, i.e. Devonian-Early Carboniferous) indicate that by these times the pre-Khuff section was already deposited and undergoing burial diagenesis. The interpretation of gravity data indicates that in Paleozoic basinal regions (e.g. between the Burgan Arch and Umm Gudair Anticline), the Paleozoic sedimentary section is likely to be more complete and may exceed 10,000 ft in thickness.

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