EurekaMag.com logo
+ Site Statistics
References:
53,214,146
Abstracts:
29,074,682
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Evolution of the Archean and Paleoproterozoic lower crust beneath the Trans-North China Orogen and the Western Block of the North China Craton



Evolution of the Archean and Paleoproterozoic lower crust beneath the Trans-North China Orogen and the Western Block of the North China Craton



Gondwana Research 22(1): 73-85



We report U-Pb ages and Hf isotopes of zircons in granulites from two continental suture zones in the North China Craton (NCC) from granulite xenoliths entrained in the Cenozoic Hannuoba basalts within the Trans-North China Orogen (TNCO) that amalgamates the Western and Eastern Blocks, and from a mafic granulite associated with ultrahigh-temperature (UHT) granulites within the Inner Mongolia Suture Zone (IMSZ) that welds the Yinshan and Ordos Blocks. The zircons in these rocks, together with the inherited zircons from Mesozoic subalkalic intrusives of these regions, show several distinct U-Pb age populations and provide constraints on the evolution of the lower crust beneath the NCC. Parts of the older zircons from the TNCO yield discordant data that project to ages of about 2.5 to 2.7 Ga. These old zircons show Hf TDMmodel ages of 2.6-2.9 Ga suggesting the existence of Archean lower crust beneath the TNCO, which is coupled with the Neoarchean metamorphic basement and greenstone belt. A major zircon population grew at 1.75 ~ 2. Ga, consistent with the timing of the Paleoproterozoic collision between the various crustal blocks within the NCC, suggesting that this event had a significant effect on the Archean lower crust. The older inherited zircons from the Western Block also yield discordant data that project to younger ages of about 1.8 to 1.9 Ga. This age is consistent with the timing of intrusion of the mafic magmatic protoliths of the granulites associated with the UHT rocks in the khondalite belt within the IMSZ. These older zircons yield Hf TDMmodel ages of 2.-2.5 Ga suggesting that the lower crust beneath the Western Block in the NCC to be dominantly Paleoproterozoic, and decoupled with the Archean metamorphic basement of the region. Yet another population of zircons from the Hannuoba banded granulite xenoliths, garnet-bearing pyroxenite cumulate and dark pyroxenite xenoliths yield a large spread of Phanerozoic concordant ages ranging from 47 Ma to 4 Ma with peaks at 315 Ma, 22 23 Ma, 12 Ma and 46 Ma. The Late Paleozoic zircons predominantly occur in the garnet-bearing pyroxenite xenoliths and yield variable ?Hf(t) values of ? 24 to + 18. Triassic ~ Cretaceous zircons mainly occur in the banded granulite xenoliths and yield highly variable ?Hf(t) values, ranging from ? 48 to + 16. The Tertiary zircons occur only in the dark pyroxenite xenoliths and show a restricted ?Hf(t) with a dominant range from to + 18. These data suggest episodic magmatic underplating in the ancient lower crust of the NCC, lasting continuously throughout Phanerozoic, producing zircons from the underplated magmas or providing the heat source for the recrystallization of zircons from the ancient crust. Our data clearly demonstrate the important events of Phanerozoic magmatic underplating beneath the Neoarchean - Paleoproterozoic crust of the NCC.Different generations of zircons found in granulite and pyroxenite xenoliths. Lower crust beneath the TNCO formed in the Archean. Paleoproterozoic tectonic event had a significant imprint in the crustal evolution. Episodic underplating modified isotopic composition of the ancient lower crust.

(PDF same-day service: $19.90)

Accession: 036203783

Download citation: RISBibTeXText

DOI: 10.1016/j.gr.2011.08.011



Related references

Neoarchean-Paleoproterozoic terrane assembly and Wilson cycle in the North China Craton: an overview from the central segment of the Trans-North China Orogen. Earth-Science Reviews 182: 1-27, 2018

Os isotope evidence for diachronous formation of lithospheric mantle beneath the Trans-North China Orogen, North China Craton. Geochimica et Cosmochimica Acta 74.12, Suppl. 1: A613, 2010

Is the Ordos Block Archean or Paleoproterozoic in age? Implications for the Precambrian evolution of the North China Craton. American Journal of Science 313(7): 683-711, 2013

Archean-Paleoproterozoic crustal evolution of the Ordos Block in the North China Craton: Constraints from zircon UPb geochronology and Hf isotopes for gneissic granitoids of the basement. Precambrian Research 267: 121-136, 2015

Complex evolution of the lower crust beneath the southeastern North China Craton: the Junan xenoliths and xenocrysts. Lithos 206-207: 113-126, 2014

Paleoproterozoic post-orogenic evolution of the North China Craton; geochemical and isotopic constraints from the Xiyanghe Group along the southern margin of the North China Craton. Geochimica et Cosmochimica Acta 71(15S): A388, 2007

Late Archean to Paleoproterozoic evolution of the North China Craton; key issues revisited. Precambrian Research 136(2): 177-202, 2005

U-Pb and Hf-isotope analysis of zircons in mafic xenoliths from Fuxian kimberlites; evolution of the lower crust beneath the North China Craton. Contributions to Mineralogy and Petrology 148(1): 79-103, 2004

Tectonic evolution of the North China Block; from orogen to craton to orogen. Geological Society, London, Special Publications 280(1): 1-34, 2007

Metamorphic evolution and tectonic implications of the Qianlishan-Zhuozishan Complex, westernmost part of the Paleoproterozoic khondalite belt in the western block of the North China Craton. Geochimica et Cosmochimica Acta 71(15S): A1146, 2007

Metamorphism and geochronology of the Luoning metamorphic terrane, southern terminal of the Palaeoproterozoic Trans-North China Orogen, North China Craton. Precambrian Research 264: 156-178, 2015

High-pressure metamorphism of mafic granulites from the Trans-North China Orogen; implications for Palaeoproterozoic amalgamation of the North China Craton. Abstracts - Geological Society of Australia 56: 56-59, 1999

Nd isotopic and geochemical constraints on the provenance and tectonic setting of the low-grade meta-sedimentary rocks from the Trans-North China Orogen, North China Craton. Journal of Asian Earth Sciences 94: 173-189, 2014

Crustal growth and intracrustal recycling in the middle segment of the Trans-North China Orogen, North China Craton a case study of the Fuping Complex. Geological Magazine 149(04): 729-742, 2012

Late Paleoproterozoic (1900-1800 Ma) nappe stacking and polyphase deformation in the Hengshan-Wutaishan area; implications for the understanding of the Trans-North China Belt, North China Craton. Precambrian Research 156(1-2): 85-106, 2007