U–Pb ages for magmatism and deformation in the New Quebec Orogen

1997 ◽  
Vol 34 (5) ◽  
pp. 716-723 ◽  
Author(s):  
N. Machado ◽  
T. Clark ◽  
J. David ◽  
N. Goulet

The New Quebec Orogen is a Paleoproterozoic fold and thrust belt, active from 2.17 to 1.77 Ga, bordering the eastern margin of the Archean Superior Province. The orogen developed on a long-lived, passive continental margin and comprises two volcanic – sedimentary sequences. The ages presented in this study help to bracket the magmatic and deformational history of the orogen. A glomeroporphyritic gabbro from the Hellancourt Formation was dated at 1874 ± 3 Ma and a rhyodacite from the upper Murdoch Formation yielded an identical age of 1870 ± 4 Ma. These data allow the correlation of the two units and indicate that they are 10–14 Ma younger than the estimated age for the Sokoman Formation. These ages, together with already published work, indicate that magmatism related to the younger magmatic event occurred at 1884–1870 Ma. Albitized pelites from the Murdoch Formation contain euhedral detrital zircons 2707–2690 Ma old, indicating that the source rocks were Archean. An undeformed monzonitic intrusion occurring close to Nachicapau Lake is 1813 ± 4 Ma old and is the lower limit for the age of deformation in the central sector of the orogen.

2016 ◽  
Vol 154 (5) ◽  
pp. 1127-1154 ◽  
Author(s):  
YU WANG ◽  
CHIN-HO TSAI ◽  
LIYUN ZHOU ◽  
YAN QIU ◽  
GUIHUA SUN

AbstractIt remains unclear whether a crystalline basement exists in SE China (including Taiwan), whether the formation of the Tananao metamorphic belt in Taiwan was linked to subduction of the Palaeo-Pacific Plate, and whether the source rocks of the sedimentary sequences in the metamorphic belts are late Mesozoic or Palaeozoic in age. Field investigations and zircon age data in the present study indicate that there is no pre-Palaeozoic gneiss (crystalline basement) in Taiwan (although orthogneisses were produced during deformation and metamorphism of Mesozoic granites), and investigations of the metasediments show that the sedimentary sequences in the Tailuko and Yuli belts are similar. Moreover, LA-ICP-MS dating of detrital zircons from the Pingtan–Dongshan belt in Fujian Province yields a cluster of 206Pb–238U ages at ~ 210–190 Ma, and the Tailuko and Yuli belts in Taiwan have similar clusters of detrital zircon ages at 200 Ma, 160 Ma, 120 Ma and 110 Ma, as well as a later overprinting caused by arc–continent collision. The cathodoluminescence images and trace-element characteristics of the zircons show that they were originally magmatic in origin. This finding, combined with the Hf isotope data, indicates that the sources of sediments in the Tananao belt (Tailuko and Yuli belts) were relatively close to an active continental margin, and that both the Tailuko and Yuli belts have similar sedimentary sources. From the margin of the Chinese mainland to Taiwan, the metasediments seem to represent a continuous sequence of deposits ranging in age from Jurassic to Cretaceous, but with the sediments becoming progressively younger towards the east. It can be inferred that the sediments in the Tailuko and Yuli belts were continental-shelf sequences with sources in SE China.


2006 ◽  
Author(s):  
A. I. Eliseev ◽  
◽  
A. I. Antoshkina ◽  
V. A. Saldin ◽  
N. Yu. Nikulova ◽  
...  

Paleozoic sedimentary basins of the northeast European Platform is a component of large megabasin of the northeast passive continental margin of the European continent in the Paleozoic. The establishment of a connection between a paleodynamic history of a basin and its sedimentary formations types, which are the most reliable indicators of geodynamic conditions, is one of the primary problems of modern lithology. Reliable indicators at geodynamic reconstructions are genetically predetermined by laterial and vertical lines of the sedimentary formations. Formations and lithological complexes being the brightest indicators of the paleodynamic regimes change of the basin have been considered formations lines of the passive continental margin of the westuralian type during the Paleozoic.


Tectonics ◽  
2018 ◽  
Vol 37 (8) ◽  
pp. 2586-2607 ◽  
Author(s):  
Stefano Tavani ◽  
Mariano Parente ◽  
Stefano Vitale ◽  
Alessandro Iannace ◽  
Amerigo Corradetti ◽  
...  

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 371
Author(s):  
Xiaofeng Xie ◽  
Zhenning Yang ◽  
Huan Zhang ◽  
Ali Polat ◽  
Yang Xu ◽  
...  

The middle Mesoproterozoic is a crucial time period for understanding the Precambrian tectonic evolutionary history of the northern Yangtze Block and its relationship with the supercontinent Columbia. The Dagushi Group (Gp) is one of the Mesoproterozoic strata rarely found at the northern margin of the Yangtze Block. U–Pb geochronology and Lu–Hf isotopic analyses of detrital zircons were analyzed for three metamorphic quartz sandstone samples collected from the Luohanling and Dangpuling formations of the Dagushi Gp. These metasandstones yielded major zircon populations at ~2.65 Ga and ~1.60 Ga, respectively. The ~1.60 Ga ages first discovered yield a narrow range of ɛHf(t) values from −1.8 to +1.8, which lie above the old crust evolutionary line of the Yangtze Block, suggesting the addition of mantle material. Trace element data indicate that ~1.60 Ga detrital zircons share a basic provenance, whereby they have low Hf/Th and high Nb/Yb ratios. Zircon discrimination diagrams suggest that the ~1.60 Ga detrital zircon source rocks formed in an intra-plate rifting environment. Dagushi Gp provenance studies indicate that the ~1.60 Ga detrital zircon was most likely sourced from the interior Yangtze Block. Thus, we suggest that the late Paleoproterozoic to early Mesoproterozoic continental break-up occurred at the northern margin of the Yangtze Block.


2002 ◽  
Vol 139 (2) ◽  
pp. 131-144 ◽  
Author(s):  
PETER A. CAWOOD ◽  
CHARLES A. LANDIS ◽  
ALEXANDER A. NEMCHIN ◽  
SHIGEKI HADA

Ion microprobe analyses of detrital zircons in the Te Akatarawa Terrane, New Zealand, reveal that the age of unfossiliferous turbidites overlying a fusuline- and coral-bearing limestone block olistostromal mélange is no older than 255±4 Ma (Late Permian). This is approximately 15 m.y. younger than the Kungurian age of the fusulinid limestone. We interpret this to indicate collapse of a Permian oceanic seamount as it entered a subduction zone along the Pacific margin of Gondwana. These turbidites differ markedly in composition from adjoining Permian to Middle Triassic sand-stones of the Torlesse Terrane. Detrital zircon age data indicate predominantly Permian and Carboniferous ages for source rocks supplying the Te Akatarawa turbidites, but also reveal significant earlier Palaeozoic and Proterozoic components, ranging back to 1.9 Ga. The warm-water setting of limestone blocks and the short 15 m.y. time period between sedimentation and accretion onto a continental margin require the limestone to have formed in a low-latitude position probably off the northeast Australian (New Guinea) margin of Gondwana. Zircons within the sample underwent re-crystallization at around 230±11 Ma which may be related to alteration during accretion in a subduction zone environment. Over a period of 100 to 150 m.y. from 255 Ma the terrane underwent more than 5000 km translation along the continental margin southward to its current location as an exotic mini-terrane enclosed within the New Zealand Torlesse Terrane.


1993 ◽  
Vol 30 (1) ◽  
pp. 29-41 ◽  
Author(s):  
J. K. Mortensen

U–Pb zircon ages for 15 volcanic and plutonic units in the Noranda and Kirkland Lake areas help constrain the history of volcanism, plutonism, sedimentation, and deformation in the south-central part of the Abitibi belt. Volcanism occurred over an interval of at least 50 Ma, beginning with the deposition of the volcanic and volcaniclastic units within the Pacaud Structural Complex at 2747 Ma. Following a period of apparent quiescence, magmatism resumed at 2730–2725 Ma with the eruption of volcanic rocks in the Normétal and Lac Abitibi area. From 2715 until about 2698 Ma, volcanism occurred sporadically throughout much of the area, culminating in the eruption of the Blake River Group from 2703 to 2698 Ma. Several large intrusive bodies yield ages that indicate that they are plutonic equivalents of the Blake River Group. Plutons that are considered to have been emplaced during the Kenoran orogeny give ages that are only slightly younger than the youngest volcanic units of the Blake River Group, emphasizing the very rapid onset of Kenoran deformation following the cessation of volcanic activity.The Cléricy syenite, dated at 2682 ± 3 Ma, postdates the main period of Kenoran deformation in this area and intrudes sedimentary rocks of the Kewagama Group which contain detrital zircons as young as 2687 Ma. These data suggest that the Kewagama Group is the same age as late sedimentary sequences such as the Timiskaming Group and may have been deposited in a similar tectonic setting.


2016 ◽  
Vol 53 (11) ◽  
pp. 1312-1335 ◽  
Author(s):  
Boris A. Natal’in ◽  
Gürsel Sunal ◽  
Erkan Gün ◽  
Bo Wang ◽  
Yang Zhiqing

The Strandja Massif, northwestern Turkey, forms a link between the Balkan Zone of Bulgaria, which is correlated with the Variscan orogen in Europe, and the Pontides, where Cimmerian structures are prominent. Five fault-bounded tectonic units form the massif structure. (1) The Kırklareli Unit consists of the Paleozoic basement intruded by the Carboniferous to Triassic Kırklareli metagranites. It is unconformably overlain by Permian and Triassic metasediments. (2) The Vize Unit that is made of Neoproterozoic metasediments, which are intruded by Cambrian metagranites, and overlain by the pre-Ordovician molasse. Unconformably laying the Ordovician quartzites pass upward into quartz schists and then to alternating marble and chert of, possibly, latest Devonian age. Rocks of the Vize Unit are intruded by the late Carboniferous metagranites. The Vize Unit may be correlated with the passive continental margin of the Istanbul Zone. (3) The Mahya accretionary complex and (4) the paired Yavuzdere magmatic arc were formed in the Carboniferous. (5) Nappes consisting of the Jurassic dolomites and marbles thrust to the north in late Jurassic – early Cretaceous time. They occupy the highest structural position on all above-mentioned tectonic units. Tectonic subdivision of the Strandja Massif is supported by new 18 ages of magmatic and detrital zircons. The long duration of subduction-related magmatism in the region and its continuity in the Triassic contradicts with the widely accepted ideas about the dominance of the passive continental margin settings in the tectonic evolution of the Strandja Massif. The massif is interpreted as a fragment of the long-lived, Cambrian to Triassic Silk Road magmatic arc. At least since the late Paleozoic this arc evolved on the northern side of Paleo-Tethys.


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