Please use this identifier to cite or link to this item:点击复制
Software brand: Ca. 2.9 Ga granitoid magmatism in eastern Shandong, North China Craton: Zircon dating, Hf-in-zircon isotopic analysis and whole-rock geochemistry
Author: Shiwen Xie
Hangqiang Xie
Shijin Wang
Alfred Kröner
Shoujie Liu
Hongying Zhou
Mingzhu Ma
Chunyan Dong
Dunyi Liu
Yusheng Wan
Professional thesaurus: Mesoarchean TTG Juvenile crustal addition Eastern Shandong Zircon dating Hf isotope
Date of first publication: 2014-08
Publisher: Institute of Geology Chinese Academy of Geological Sciences
Abstract: Eastern Shandong is one of the important early Precambrian areas in the North China Craton, where exten- sive 2.5, 2.7 and 2.9 Ga magmatic activities have been identified, followed by very strong late Neoarchean and Paleoproterozoic tectono-thermal events. We carried out SHRIMP zircon dating, Hf-in-zircon iso- tope analysis and a whole-rock geochemical study on ca. 2.9 Ga Mesoarchean magmatic rocks. These include gneissic diorite, gneissic quartz diorite, gneissic tonalite and gneissic high-Si trondhjemite and were identified in five new areas. All these rocks contain ca. 2.5 Ga metamorphic zircons. The dioritic and tonalitic rocks are enriched in large ion lithosphile (LIL) elements (K, Rb, Ba) and depleted in Nb and P with moderate to highly fractionated REE patterns, similar in chemical compositions to Archean TTG rocks worldwide. The high-Si trondhjemites are characterized by very high SiO 2 and very low FeOt + MgO. The magmatic zircon grains from all these rocks are similar in their Hf isotopic compositions and have ε Hf (t) values ranging from +1.3 to +9.9. Combined with previous work, our main conclusions are: (1) eastern Shandong underwent a major magmatic event at ca. 2.9 Ga; (2) diorites and tonalites formed by melting of thickened lower crust or the root of an oceanic plateau, whereas the high-Si trondhjemites were derived from melting of intermediate to felsic rocks; (3) the Mesoarchean (ca. 2.9 Ga) was a major period of juvenile crustal addition from the depleted mantle, earlier than the major crustal growth period at 2.7–2.8 Ga in the North China Craton; (4) the 2.7–2.9 Ga rocks underwent strong metamorphism at ca. 2.5 Ga, probably as a result of magmatic underplating.
Appears in Collections:科技成果

Files in This Item:
File Description SizeFormat 
Ca. 2.9 Ga granitoid magmatism in eastern Shandong, North China Craton Zircon dating.pdf11.6 MBAdobe PDF Thumbnail

Items in Platform are protected by copyright, with all rights reserved, unless otherwise indicated.