scholarly journals Age and sources of the metasedimrntary rocks of the Tokur terrane in the Mongol-Okhotsk fold belt: results of the U–Pb geoсhronological and Lu–Hf isotope studies

2019 ◽  
Vol 486 (4) ◽  
pp. 446-450
Author(s):  
V. A. Zaika ◽  
A. A. Sorokin ◽  
A. P. Sorokin
Keyword(s):  
Detrital Zircons ◽  
Hf Isotope ◽  
Fold Belt ◽  
Metasedimentary Rocks ◽  
The North ◽  
Icp Ms ◽  
North Asia ◽  
Southeastern Margin ◽  
Isotope Studies ◽  
Metamorphic Complexes

This paper presents the results of U–Pb (LA–ICP–MS) and Lu–Hf ­isotope studies of detrital zircons from metasedimentary rocks of the Tokur Terrane. It has been shown that metasedimentary rocks of the Tokur and Ekimchan formations are characterized by similar age peaks of detrital zircons, which indicates a close (or same) age of these formations. The lower age of the sedimentation is determined by the age of the youngest zircons of 326–323 Ma. The upper age boundary is determined of 254–251 Ma, based on the intruded of the Late Permian granitoids. The main sources of zircons in the metasedimentary rocks of the Tokur Terrane are the igneous and metamorphic complexes of the southeast framing of the North Asia Craton. The Tokur Terrane can be considered as a fragment of the Paleozoic accretionary complex, the formation in front of the southeastern margin of the North Asia Craton.

scholarly journals Age and sources of the Lower Mesozoic metasedimentary rocks of the Un'ja-Bom terrane in the Mongol-Okhotsk fold belt: results of the U–Th–Pb geohronological (LA–ICP–MS) AND Sm–Nd isotope studies

2019 ◽  
Vol 484 (4) ◽  
pp. 455-459
Author(s):  
V. A. Zaika ◽  
A. A. Sorokin ◽  
V. P. Kovach ◽  
A. P. Sorokin ◽  
A. B. Kotov
Keyword(s):  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Fold Belt ◽  
Relative Probability ◽  
Nd Isotope ◽  
Metasedimentary Rocks ◽  
Icp Ms ◽  
Isotope Studies ◽  
Geochemical Studies ◽  
Age Estimates

The results of the U—Th—Pb geochronological studies indicate that in the Un’ja-Bom terrane the youngest peaks on the relative probability curves of ages are 207 and 212 Ma for zircons from the metasiltstone of the Kurnal formation and from the metasiltstone of the Amkan formation. Similar age estimates for the youngest peaks were obtained for the detrital zircons from the metasedimentary rocks of the Tukuringra terrain of the eastern part of the Mongol-Okhotsk belt, which indicates that the Lower Mesozoic flyschoid complexes in the structure of this belt are developed much wider than is currently believed. The results obtained in our U—Th—Pb geochronological and Sm—Nd isotope geochemical studies suggest’s that the sedimentary rocks material was carried to the sedimentation basin mainly from the continental massifs of the Amur superterrane.

scholarly journals Zircon geochronology from the Kangaatsiaq– Qasigiannguit region, the northern part of the 1.9–1.8 Ga Nagssugtoqidian orogen, West Greenland

2006 ◽  
Vol 11 ◽  
pp. 87-100 ◽  
Author(s):  
Kristine Thrane ◽  
James N. Connelly
Keyword(s):  
Detrital Zircons ◽  
Zircon Geochronology ◽  
West Greenland ◽  
Metasedimentary Rocks ◽  
The North ◽  
Ion Probe ◽  
Icp Ms ◽  
Supracrustal Belt ◽  
Granitoid Rocks ◽  
Age Patterns

The Kangaatsiaq–Qasigiannguit region in the northern part of the Palaeoproterozoic Nagssugtoqidian orogen of West Greenland consists of poly-deformed orthogneisses and minor occurrences of interleaved, discontinuous supracrustal belts. Laser ablation ICP-MS 207Pb/206Pb analyses of detrital zircons from four metasedimentary rocks (supplemented by ion probe analysis of one sample) and igneous zircons from six granitoid rocks cutting metasedimentary units indicate that the supracrustal rocks in the Kangaatsiaq–Qasigiannguit (Christianshåb) region are predominantly Archaean in age. Four occurrences of metasedimentary rocks are clearly Archaean, two have equivocal ages, and only one metasedimentary unit, from within the Naternaq (Lersletten) supracrustal belt, is demonstrably Palaeoproterozoic and readily defines a large fold complex of this age at Naternaq. The 2.9–2.8 Ga ages of detrital Archaean grains are compatible with derivation from the local basement orthogneisses within the Nagssugtoqidian orogen. The detrital age patterns are similar to those of metasediments within the central Nagssugtoqidian orogen but distinct from age patterns in metasediments of the Rinkian belt to the north, where there is an additional component of pre-2.9 Ga zircons. Synkinematic intrusive granitoid rocks constrain the ages of some Archaean deformation at 2748 ± 19 Ma and some Palaeoproterozoic deformation at 1837 ± 12 Ma.

scholarly journals AGE AND SOURCES OF PROTOLITHS OF METASEDIMENTARY ROCKS IN THE EASTERN TUKURINGRA TERRANE OF THE MONGOL-OKHOTSK FOLD BELT: RESULTS OF U-TH-PB, LU-HF, AND SM-ND ISOTOPE STUDIES

2021 ◽  
Vol 40 (3) ◽  
pp. 16-27
Author(s):  
V.A. Zaika ◽  
◽  
A.A. Sorokin ◽  
Keyword(s):  
Early Jurassic ◽  
Late Triassic ◽  
Fold Belt ◽  
North Asian Craton ◽  
Nd Isotope ◽  
Metasedimentary Rocks ◽  
Isotope Data ◽  
The North ◽  
Early Mesozoic ◽  
Isotope Studies

The article presents detrital zircon U-Th-Pb and Lu-Hf isotope data for metasedimentary rocks from the eastern Tukuringra Terrane, as well as whole-rock Sm-Nd isotope data. Our analyses show that the zircons in metasedimentary rocks are mostly early Mesozoic in age. Early Paleozoic and Neoproterozoic zircons are also common, whereas early Precambrian zircons are virtually absent. The age of the youngest zircon population places a lower age limit on the age of the Tungalin Formation at 204 Ma (Late Triassic, Rhaetian), the Dugda Formation at 181 Ma (Early Jurassic, Toarcian), and the Tangomen Formation at 189 Ma (Early Jurassic, Pliensbachian). Essentially all Mesozoic, Paleozoic and Neoproterozoic zircons are characterized by Neo- and Mesoproterozoic Hf-model ages (tHf(DM) = 1.41–0.46 Ga, tHf(C) = 1.55–0.49) and Mesoproterozoic Nd-model ages (tNd(DM) = 1.25–1.10 Ga, tNd(С) = 1.31–1.14). Our results suggest that sediments for deposition were sourced mainly from the continental Amuria Superterrane, but not from the southern margin of the North Asian Craton.

scholarly journals The country rocks of Devonian magmatism in the North Patagonian Massif and Chaitenia

2018 ◽  
Vol 45 (3) ◽  
pp. 301 ◽  
Author(s):  
Francisco Hervé ◽  
Mauricio Calderón ◽  
Mark Fanning ◽  
Robert Pankhurst ◽  
Carlos W. Rapela ◽  
...  
Keyword(s):  
Metamorphic Grade ◽  
Oceanic Island ◽  
Detrital Zircons ◽  
Island Arc ◽  
Ultramafic Rocks ◽  
The West ◽  
Metasedimentary Rocks ◽  
The North ◽  
The Andes ◽  
Late Neoproterozoic

Previous work has shown that Devonian magmatism in the southern Andes occurred in two contemporaneous belts: one emplaced in the continental crust of the North Patagonian Massif and the other in an oceanic island arc terrane to the west, Chaitenia, which was later accreted to Patagonia. The country rocks of the plutonic rocks consist of metasedimentary complexes which crop out sporadically in the Andes on both sides of the Argentina-Chile border, and additionally of pillow metabasalts for Chaitenia. Detrital zircon SHRIMP U-Pb age determinations in 13 samples of these rocks indicate maximum possible depositional ages from ca. 370 to 900 Ma, and the case is argued for mostly Devonian sedimentation as for the fossiliferous Buill slates. Ordovician, Cambrian-late Neoproterozoic and “Grenville-age” provenance is seen throughout, except for the most westerly outcrops where Devonian detrital zircons predominate. Besides a difference in the Precambrian zircon grains, 76% versus 25% respectively, there is no systematic variation in provenance from the Patagonian foreland to Chaitenia, so that the island arc terrane must have been proximal to the continent: its deeper crust is not exposed but several outcrops of ultramafic rocks are known. Zircons with devonian metamorphic rims in rocks from the North Patagonian Massif have no counterpart in the low metamorphic grade Chilean rocks. These Paleozoic metasedimentary rocks were also intruded by Pennsylvanian and Jurassic granitoids.

Sign in / Sign up

Export Citation Format

Share Document