scholarly journals U-Pb geochronology and geochemistry from the northeastern New River belt, southern New Brunswick, Canada: significance of the Almond Road Group to the Ganderian platformal margin

2018 ◽  
pp. 147-170
Author(s):  
Susan C. Johnson ◽  
Gregory R. Dunning ◽  
Brent V. Miller
Keyword(s):  
New Brunswick ◽  
Detrital Zircon ◽  
Early Cambrian ◽  
The West ◽  
Zircon Age ◽  
Early Ordovician ◽  
Icp Ms ◽  
Age Limit ◽  
Feldspathic Sandstone ◽  
Dominant Peak

The Almond Road Group in the northeastern New River belt comprises two formations: the basal Snider Mountain Formation contains orthoquartzite, feldspathic quartzite, and quartzite pebble conglomerate; the gradationally overlying Ketchum Brook Formation is composed of feldspathic sandstone, laminated dark siltstone and shale, overlain by mafic lithic tuffs and basaltic flows. The Almond Road Group overlies latest Ediacaran to earliest Cambrian (early Fortunian) pyroclastic, volcaniclastic, and epiclastic rocks of the Belleisle Bay Group. Based in part on this relationship, the Almond Road Group was thought to be Early Cambrian, although an upper age limit had never been determined. A U–Pb (zircon) age of 475 ± 2 Ma for the West Scotch Settlement porphyry, a small felsic hypabyssal intrusion emplaced into the Ketchum Brook Formation, demonstrates that the Almond Road Group is no younger than Early Ordovician (early Floian) age. Its age is further constrained by LA ICP-MS detrital zircon data from a basal quartzite in the Snider Mountain Formation. Results show a dominant peak in the Ediacaran (ca. 575 Ma), with the youngest coherent cluster of ages at ca. 530–520 Ma. Together these data support a Cambrian age for the quartz-rich Almond Road Group and its platformal relationship to Ganderia.

Caledonian terrane amalgamation of Svalbard: detrital zircon provenance of Mesoproterozoic to Carboniferous strata from Oscar II Land, western Spitsbergen

2013 ◽  
Vol 150 (6) ◽  
pp. 1103-1126 ◽  
Author(s):  
DETA GASSER ◽  
ARILD ANDRESEN
Keyword(s):  
Detrital Zircon ◽  
Large Scale ◽  
Strike Slip ◽  
Western Coast ◽  
Zircon Age ◽  
The North ◽  
Tectonic History ◽  
Icp Ms ◽  
Depositional Age ◽  
Sveconorwegian Orogen

AbstractThe tectonic origin of pre-Devonian rocks of Svalbard has long been a matter of debate. In particular, the origin and assemblage of pre-Devonian rocks of western Spitsbergen, including a blueschist-eclogite complex in Oscar II Land, are enigmatic. We present detrital zircon U–Pb LA-ICP-MS data from six Mesoproterozoic to Carboniferous samples and one U–Pb TIMS zircon age from an orthogneiss from Oscar II Land in order to discuss tectonic models for this region. Variable proportions of Palaeo- to Neoproterozoic detritus dominate the metasedimentary samples. The orthogneiss has an intrusion age of 927 ± 3 Ma. Comparison with detrital zircon age spectra from other units of similar depositional age within the North Atlantic region indicates that Oscar II Land experienced the following tectonic history: (1) the latest Mesoproterozoic sequence was part of a successor basin which originated close to the Grenvillian–Sveconorwegian orogen, and which was intruded byc. 980–920 Ma plutons; (2) the Neoproterozoic sediments were deposited in a large-scale basin which stretched along the Baltoscandian margin; (3) the eclogite-blueschist complex and the overlying Ordovician–Silurian sediments probably formed to the north of the Grampian/Taconian arc; (4) strike-slip movements assembled the western coast of Spitsbergen outside of, and prior to, the main Scandian collision; and (5) the remaining parts of Svalbard were assembled by strike-slip movements during the Devonian. Our study confirms previous models of complex Caledonian terrane amalgamation with contrasting tectonic histories for the different pre-Devonian terranes of Svalbard and particularly highlights the non-Laurentian origin of Oscar II Land.

Lower Cambrian (Branchian) trilobites and biostratigraphy of the Hanford Brook Formation, southern New Brunswick

2000 ◽  
Vol 74 (5) ◽  
pp. 858-878 ◽  
Author(s):  
Stephen R. Westrop ◽  
Ed Landing
Keyword(s):  
New Species ◽  
Nova Scotia ◽  
North America ◽  
New Brunswick ◽  
Lower Cambrian ◽  
Early Cambrian ◽  
The West ◽  
Middle Cambrian ◽  
Sequence Stratigraphic ◽  
Two New Species

The Hanford Brook Formation, one of the classic Cambrian units of Avalonian North America, contains at least eight species of endemic trilobites, including Berabichia milleri Westrop n. sp., that are assigned to seven genera. The vertical succession of faunas is far more complex than has been recognized previously, with each member containing a lithofacies-specific assemblage. These are, in ascending order: a bradoriid-linguloid Association without trilobites in the nearshore St. Martin's Member, a Protolenus Association in dysaerobic siltstones and sandstones of the Somerset Street Member, and a Kingaspidoides-Berabichia Association in hummocky cross-stratified sandstones of the Long Island Member that overlie a parasequence boundary at Hanford Brook. Due to the breakdown of biogeographic barriers in the late Early Cambrian, two new species-based zones, the Protolenus elegans and Kingaspidoides cf. obliquoculatus zones, share trilobite genera with the Tissafinian Stage of Morocco. This generic similarity has been the basis for correlation of this upper Lower Cambrian interval on the Avalon continent with the West Gondwanan lowest Middle Cambrian. However, the clear facies control on the occurrence of genera in the Hanford Brook Formation and the presence of an abrupt faunal break and unconformity at the base of the Tissafinian in Morocco makes this correlation questionable. The Hanford Brook Formation may represent a late Early Cambrian interval unknown in Gondwana. Sequence-stratigraphic criteria even raise the possibility that the Protolenus Association is the biofacies equivalent of Callavia broeggeri Zone faunas of the Brigus Formation of Newfoundland, Nova Scotia and Massachusetts.

scholarly journals The U-Pb detrital zircon signature of West Antarctic ice stream tills in the Ross embayment, with implications for Last Glacial Maximum ice flow reconstructions

2014 ◽  
Vol 26 (6) ◽  
pp. 687-697 ◽  
Author(s):  
Kathy J. Licht ◽  
Andrea J. Hennessy ◽  
Bethany M. Welke
Keyword(s):  
Last Glacial Maximum ◽  
Detrital Zircon ◽  
Ross Sea ◽  
Ice Sheet ◽  
Glacial Maximum ◽  
Ice Streams ◽  
The West ◽  
Zircon Age ◽  
Last Glacial ◽  
West Antarctic

AbstractGlacial till samples collected from beneath the Bindschadler and Kamb ice streams have a distinct U-Pb detrital zircon signature that allows them to be identified in Ross Sea tills. These two sites contain a population of Cretaceous grains 100–110 Ma that have not been found in East Antarctic tills. Additionally, Bindschadler and Kamb ice streams have an abundance of Ordovician grains (450–475 Ma) and a cluster of ages 330–370 Ma, which are much less common in the remainder of the sample set. These tracers of a West Antarctic provenance are also found east of 180° longitude in eastern Ross Sea tills deposited during the last glacial maximum (LGM). Whillans Ice Stream (WIS), considered part of the West Antarctic Ice Sheet but partially originating in East Antarctica, lacks these distinctive signatures. Its U-Pb zircon age population is dominated by grains 500–550 Ma indicating derivation from Granite Harbour Intrusive rocks common along the Transantarctic Mountains, making it indistinguishable from East Antarctic tills. The U-Pb zircon age distribution found in WIS till is most similar to tills from the west-central Ross Sea. These data provide new specific targets for ice sheet models and can be applied to pre-LGM deposits in the Ross Sea.

scholarly journals Zircon ages delimit the provenance of a sand extrudite from the Botucatu Formation in the Paraná volcanic province, Iraí, Brazil

2015 ◽  
Vol 87 (3) ◽  
pp. 1611-1622 ◽  
Author(s):  
VITER M. PINTO ◽  
LÉO A. HARTMANN ◽  
JOÃO O.S. SANTOS ◽  
NEAL J. MCNAUGHTON
Keyword(s):  
Detrital Zircon ◽  
Lower Triassic ◽  
Flood Basalt ◽  
Early Cambrian ◽  
Ion Microprobe ◽  
Zircon Age ◽  
Volcanic Province ◽  
Igneous Activity ◽  
Botucatu Formation ◽  
Age Determinations

Ion microprobe age determinations of 102 detrital zircon crystals from a sand extrudite, Cretaceous Paraná volcanic province, set limits on the origin of the numerous sand layers present in this major flood basalt province. The zircon U-Pb ages reflect four main orogenic cycles: Mesoproterozoic (1155-962 Ma), latest Proterozoic-early Cambrian (808-500 Ma) and two Palaeozoic (Ordovician- 480 to 450 Ma, and Permian to Lower Triassic- 296 to 250 Ma). Two additional small concentrations are present in the Neoarchean (2.8 to 2.6 Ga) and Paleoproterozoic (2.0 to 1.7 Ga). Zircon age peaks closely match the several pulses of igneous activity in the Precambrian Brazilian Shield and active orogeny in Argentina. A main delimitation of the origin of the sand is the absence of zircon ages from the underlying Cretaceous basalts, thus supporting an injectite origin of the sand as an extrudite that emanated from the paleoerg that constitutes the Botucatu Formation.

Duration of the Early Cambrian: U-Pb ages of volcanic ashes from Avalon and Gondwana

1998 ◽  
Vol 35 (4) ◽  
pp. 329-338 ◽  
Author(s):  
Ed Landing ◽  
Samuel A Bowring ◽  
Kathleen L Davidek ◽  
Stephen R Westrop ◽  
Gerd Geyer ◽  
...  
Keyword(s):  
New Brunswick ◽  
Lower Cambrian ◽  
Young Age ◽  
Early Cambrian ◽  
Zircon Age ◽  
South Wales ◽  
Volcanic Ashes

Volcanic zircons from three ashes give a U-Pb date of 511 ± 1 Ma on trilobite-bearing, upper Lower Cambrian (upper Branchian Series) strata of southern New Brunswick that correlate into the Siberian middle Botomian - Toyonian Stage interval. This very young age on the late, but not latest, Early Cambrian of Avalon is consistent both with a 519 ± 1 Ma age on the older Caerfai Bay Shales of south Wales that are tentatively correlated into strata with the oldest Avalonian trilobites (lower Branchian) and with a 517 ± 1.5 Ma age on the Antatlasia gutta-pluviae Zone (trilobites) of Morocco. Determination of a 522 ± 2 Ma zircon age on the Moroccan subtrilobitic Lower Cambrian Lie de vin Formation is consistent with an earlier reported 521 ± 7 Ma age from the Lie de vin but suggests that a 526 ± 4 Ma age on Australian trilobite-bearing Lower Cambrian rocks may be too old. A 33+ Ma duration of the Avalonian Early Cambrian and an 8+ Ma length of the Avalonian trilobite-bearing Lower Cambrian support proposals that most Cambrian time was Early Cambrian and the majority of the Early Cambrian was pretrilobitic.

scholarly journals Early Cambrian U-Pb zircon age and Hf-isotope data from the Guasayán pluton, Sierras Pampeanas, Argentina: implications for the northwestern boundary of the Pampean arc

2016 ◽  
Vol 43 (1) ◽  
pp. 137 ◽  
Author(s):  
Juan A. Dahlquist ◽  
Sebastián O. Verdecchia ◽  
Edgardo G. Baldo ◽  
Miguel A.S. Basei ◽  
Pablo H. Alasino ◽  
...  
Keyword(s):  
Central Area ◽  
Magma Source ◽  
Western Boundary ◽  
Low Grade ◽  
Early Cambrian ◽  
Zircon Age ◽  
Sierras Pampeanas ◽  
Metasedimentary Rocks ◽  
Icp Ms

An Early Cambrian pluton, known as the Guasayán pluton, has been identified in the central area of Sierra de Guasayán, northwestern Argentina. A U-Pb zircon Concordia age of 533±4 Ma was obtained by LA-MC-ICP-MS and represents the first report of robustly dated Early Cambrian magmatism for the northwestern Sierras Pampeanas. The pluton was emplaced in low-grade metasedimentary rocks and its magmatic assemblage consists of K-feldspar (phenocrysts)+plagioclase+quartz+biotite, with zircon, apatite, ilmenite, magnetite and monazite as accessory minerals. Geochemically, the granitic rock is a metaluminous subalkaline felsic granodiorite with SiO2=69.24%, Na2O+K2O=7.08%, CaO=2.45%, Na2O/ K2O=0.71 and FeO/MgO=3.58%. Rare earth element patterns show moderate slope (LaN/YbN=8.05) with a slightly negative Eu anomalies (Eu/Eu*=0.76). We report the first in situ Hf isotopes data (εHft=-0.12 to -4.76) from crystallized zircons in the Early Cambrian granites of the Sierras Pampeanas, helping to constrain the magma source and enabling comparison with other Pampean granites. The Guasayán pluton might provide a link between Early Cambrian magmatism of the central Sierras Pampeanas and that of the Eastern Cordillera, contributing to define the western boundary of the Pampean paleo-arc.

scholarly journals Peri-Amazonian provenance of the Central Dobrogea terrane (Romania) attested by U/Pb detrital zircon age patterns

2011 ◽  
Vol 62 (4) ◽  
pp. 299-307 ◽  
Author(s):  
Ion Balintoni ◽  
Constantin Balica ◽  
Antoneta Seghedi ◽  
Mihai Ducea
Keyword(s):  
Detrital Zircon ◽  
Low Grade ◽  
Transform Fault ◽  
Zircon Age ◽  
The North ◽  
Icp Ms ◽  
Age Patterns ◽  
Geological Units ◽  
Geological Formations ◽  
Orogenic Events

Peri-Amazonian provenance of the Central Dobrogea terrane (Romania) attested by U/Pb detrital zircon age patterns The Central Dobrogea Shield is a part of the Moesia, a Paleozoic composite terrane located southward of the North Dobrogea Alpine orogen. The two geological units are separated from each other by a trans-lithospheric discontinuity, the Peceneaga-Camena transform fault. Along this fault, remnants of a Variscan orogen (i.e. North Dobrogea), recycled during the Alpine orogeny come in contact with two lithological entities of the Central Dobrogea Shield, unaffected by the Phanerozoic orogenic events: the Histria Formation, a flysch-like sequence of Ediacaran age very low-grade metamorphosed and its basement, the medium-grade metamorphosed Altîn Tepe sequence. Southward, along the reverse hidden Palazu fault, the Histria Formation meets South Dobrogea, formed of quite different geological formations. Detrital zircon from the Histria Formation yielded U/Pb LA ICP MS ages that show provenance patterns typical of peri-Amazonian terranes. Such terranes were sourced by orogens ranging from Paleoarchean to Neoproterozoic. The ages between 750 and 600 Ma differentiate the Amazonian sources from the Baltican and Laurentian sources, since they are lacking from the last ones. The youngest ages of 587 and 584 Ma suggest for the Histria Formation a maximum late Ediacaran deposition age. At the same time, the continuity of the Ordovician sediments over the Palazu fault revealed by drill-cores favours a Cambrian junction between Central and South Dobrogea.

scholarly journals U-Pb (LA-ICP-MS) age of detrital zircons and the sources of terrigenous sediments of the Ipsit suite, Karagass series (Sayan segment of the Sayan-Baikal-Patom belt)

2018 ◽  
Vol 9 (4) ◽  
pp. 1313-1329 ◽  
Author(s):  
Z. L. Motova ◽  
T. V. Donskaya ◽  
D. P. Gladkochub ◽  
V. B. Khubanov
Keyword(s):  
Detrital Zircon ◽  
Source Area ◽  
Potassium Feldspar ◽  
Detrital Zircons ◽  
Igneous Rocks ◽  
Zircon Age ◽  
Genetic Types ◽  
Terrigenous Rocks ◽  
Detrital Material ◽  
Icp Ms

The petrographic, lithogeochemical and U-Pb (LA-ICP-MS) geochronological studies were carried out to investigate the terrigenous rocks sampled from the lower part of the Ipsit suite of the Karagass series (Sayan segment of the Sayan-Baikal-Patom belt). These rocks include sandstones, aleurite sandstones and aleurolites, and their mineral compositions are close to that of arkose. Most of the studied rock samples show petrographic features typical of the epigenetic changes at the stage of catagenesis: regeneration of quartz clastic grains, pelitization of potassium-feldspar clastic grains, occurrence of clay-hydromica aggregate, sericitization of plagioclase, chloritization of biotite, and silicification of dolomite pieces, and occurrence of authigenous tourmaline. The above was confirmed by the analysis of the concentrations of petrogenic elements in the studied rocks from the lower part of the Ipsit suite. The analysis results show that the concentrations of K2O are elevated, while the concentrations of Na2O are relatively very low, which may be due to the redistribution of these elements during epigenetic transformations. According to the classification by genetic types on the basis of the system of petrochemical modules, the rocks of the lower part of the Ipsa suite are of the petrogenic nature. The acidic igneous rocks are dominant in the source area, as evidenced by the presence of granitoid and quartzite fragments in the clastogenic component, as well as the set of accessory minerals typical of the igneous rocks of the acidic composition, and the distribution pattern of rare and trace elements. According to the U-Pb (LA-ICP-MS) dating of detrital zircons from the aleurite sandstone sampled from the lower part of the Ipsit suite, the zircons are exclusively of the Archean-Early Proterozoic ages. Such ages correlate with the age of the granitoids of the Sayan complex and the felsic volcanites from the Maltsev layer of the Elash series (Biryusa block). Furthermore, the detrital-zircon age spectra of the aleurite sandstone of the lower part of the Ipsit suite are identical to the detrital-zircon age spectra of the terrigenous rocks from the underlying strata of the Shangulezh and Tagul suites of the Karagass series. This study suggests that sedimentation of the Ipsit suite of the Karagass series took place due to the influx of detrital material from the southern part of the Siberian craton into the sedimentation basin, and the acidic igneous rocks of the Biryusa block were one of the main sources of detrital material.

Initiation and evolution of forearc basins in the Central Myanmar Depression

2019 ◽  
Vol 132 (5-6) ◽  
pp. 1066-1082 ◽  
Author(s):  
Fulong Cai ◽  
Lin Ding ◽  
Qinghai Zhang ◽  
Devon A. Orme ◽  
Honghong Wei ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Upper Cretaceous ◽  
Upper Triassic ◽  
Forearc Basin ◽  
The West ◽  
Zircon Age ◽  
Shallow Marine ◽  
Western Margin ◽  
Forearc Basins ◽  
Structural High

Abstract The forearc basin in Myanmar is significant in understanding the development of continental forearc basins. We present stratigraphic, sandstone petrographic, and U-Pb detrital data from Upper Cretaceous–Eocene strata of Chindwin and Minbu sub-basins in the Central Myanmar Depression. The Upper Cretaceous lower Kabaw Formation consists of turbiditic conglomerate, sandstone, and mudstone in the Minbu sub-basin. The composition of conglomerates are mainly schist and subordinate quartz. Prominent detrital zircon age probability peaks are between 260 and 223 Ma, similar with that of Upper Triassic Pane Chaung turbidites and Kanpetlet schist on the West Burma plate. In the upper Kabaw Formation, turbiditic volcanic-rich sandstones have major age populations ranging from 103 to 70 Ma in both Minbu and Chindwin sub-basins. The Paleocene slope environment Paunggyi Formation, which overlies the Kabaw Formation, mainly consists of conglomerate, sandstone, mudstone, and tuff beds in the Minbu sub-basin. In contrast, the Paunggyi Formation in the Chindwin sub-basin is composed of sandstone and mudstone; major detrital zircon age populations from the Paunggyi Formation are between 100 and 60 Ma. Eocene strata in both basins are composed mainly of shallow marine to delta sandstone and mudstone. Major detrital zircon age populations are 100–36 Ma and 600–500 Ma. The Late Cretaceous–Eocene ages from Upper Cretaceous–Eocene strata overlap with igneous crystallization ages from the Western Myanmar Arc. We propose that the Chindwin and Minbu sub-basins developed as parts of a forearc basin along the west flank of Western Myanmar Arc (present coordinate). The forearc basin initiated in Albian time atop the continental West Burma plate due to the formation of a structural high along the western margin of West Burma plate.

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