All Title Author
Keywords Abstract

Publish in OALib Journal
ISSN: 2333-9721
APC: Only $99

ViewsDownloads

Relative Articles

Timing of Palaeoproterozoic crustal shearing in the central Fennoscandian Shield according to U-Pb data from associated granitoids, Finland

The first discovery of eclogite and Palaeoproterozoic granitoids in the Beishan area, northwestern Gansu Province, China

The first discovery of eclogite and Palaeoproterozoic granitoids in the Beishan area, northwestern Gansu Province, China

Geochemistry and petrogenesis of Jurassic high Sr/low Y granitoids in eastern China: Constrains on crustal thickness

Geochemistry and petrogene-sis of Jurassic high Sr/low Y granitoids in eastern China:Constrains on crustal thick-ness

SHRIMP zircon U-Pb dating of the Gangou granitoids, Central Tianshan Mountains, Northwest China and tectonic significances

STUDY ON THE TYPOMORPHIC CHARACTERISTICS OF ZIRCON FROM TWO DIFFERENT TYPES OF MINERALIZED GRANITOIDS OF YANSHAN OROGENY IN SOUTH CHINA
华南燕山期两种不同矿化花岗岩类中锆石标型特征的研究

Formation ages and source regions of the Palaeoproterozoic Gaofan, Hutuo and Dongjiao groups in the Wutai and Dongjiao areas of the North China Craton from SHRIMP U-Pb dating of detrital zircons: Resolution of debates over their stratigraphic relationships

SHRIMP zircon U-Pb dating of the Gangou granitoids, Central Tianshan Mountains, Northwest China and tectonic significances

Timing of late Palaeoproterozoic metamorphism in the northern Belomorian Belt, White Sea region: conclusions from U-Pb isotopic data and P-T evidence

More...

Intracratonic Palaeoproterozoic granitoids in northern Finland: prolonged and episodic crustal melting events revealed by Nd isotopes and U-Pb ages on zircon

Keywords: granites , granodiorites , migmatites , Central Lapland Granitoid Complex , partial melting , absolute age , U/Pb , Sm/Nd , Paleoproterozoic , Lapland Province , Finland

Full-Text   Cite this paper   Add to My Lib

Abstract:

Zircons from twelve Palaeoproterozoic granitoids from the Central Lapland Granitoid Complex (CLGC) and from the Hetta Complex (HC) in northern Finland were dated using the NORDSIM ion microprobe. In addition, U-Pb age determinations on zircons from two samples were made using TIMS. Results reveal a wide range of U-Pb ages from 2.13Ga to 1.76 Ga. The oldest samples include the porphyritic, weakly deformed Nilip granite, which has an ion probe concordia age of 2126±5 Ma, compatible with the previously published TIMS age of 2136±5 Ma. The Tohmo granodiorite provided a slightly younger ion microprobe age of 2105±4 Ma. The age of these two granitoids overlaps the depositional age of Karelian cratonic metasediments, suggesting that they represent an unusual tectonic setting for granitoid magmatism in the Fennoscandian Shield. The Ruoppapalo granodiorite, which is also porphyritic and weakly deformed, yielded an ion probe zircon concordia age of 1905±5 Ma, in accord with the conventional TIMS result. The strongly deformed Molkok ng s granite has an ion probe concordia age of 1855±13 Ma, which is within error limits the same as the TIMS age, 1843±23 Ma. The Pernu monzogranite has a concordia age of 1813±6 Ma. All other granitoids in the CLGC, including those of appinitic affinity, as well as a leucosome from the Kappera migmatite in the Hetta Complex, are dated at 1.79 – 1.76 Ga, although many granitoids have older inherited zircons. The abundance of deformed granitoids of this age show that intensive ductile deformation, metamorphism and melting occurred at around 1.79 – 1.76 Ga in the northern Fennoscandian Shield, coeval with post-collisional magmatism in the southern part of the Shield. Most granitoids in the Central Lapland Granitoid Complex have strongly negative εNd values (1.8 Ga), ranging from -8 to -5. It is evident that they have a major Archaean component in their source, indicating derivation from Archaean crust during crustal reworking in an intracratonic tectonic setting.

Full-Text

comments powered by Disqus

Contact Us

service@oalib.com

QQ:3279437679

微信:OALib Journal