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539662 
Journal Article 
The 1.75-1.68 Ga anortho site-mangerite-alkali granitoid-rapakivi granite suite from the northern North China Craton: Magmatism related to a Paleoproterozoic orogen 
Zhang, SH; Liu, SW; Zhao, Y; Yang, JH; Song, B; Liu, XM 
2007 
1 
Precambrian Research
ISSN: 0301-9268 
155 
3-4 
287-312 
English 
The AMGRS is a suite of anorthosite-mangerite-alkali granitoid-rapakivi granite in the northern North China Craton (NCC). New zircon SHRIMP and laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) U-Pb dating of the Damiao anorthosite, Changsaoying K-feldspar granite, Lanying anorthosite and quartz syenite and the Gubeikou K-feldspar granite yielded emplacement ages of 1726 +/- 9 Ma, 1753 +/- 23 Ma, 1739 +/- 43 Ma, 1712 +/- 15 Ma and 1692 +/- 19 Ma, respectively. Combined with previous geochronological data from the Damiao norite and mangerite and Shachang rapakivi granite, it indicates that the whole AMGRS was intruded between 1750 Ma and 1680 Ma. The Damiao anorthosites and norites exhibit a high Mg#, and this decreases from malic (up to 63) to felsic (< 10) end members. The alkali granitoids of the AMGRS are characterized by high contents of alkali (K2O + Na2O), HSFE, TFeO/MgO, molecular (K2O + Na2O)/Al2O3 and Ga/Al values, that are typical features of A-type granites. All of the diverse components of the AMGRS have similar Sr-Nd-Hf isotopic compositions with low whole-rock initial Sr-87/Sr-86 ratios of 0.703-0.704, epsilon(Nd)(T) values of -5.0 to -6.3 (with T-DM model ages of 2.34 to 2.58 Ga), and zircon epsilon(Hf)(T) values ranging from -4.1 to -7.5 (with Hf isotopic model T-DM and T-DM(C) ages ranging from 2.32 Ga to 2.43 Ga and 2.70 Ga to 2.88 Ga, respectively). This suggests that these rocks are the fractional crystallization products of one parental magma. Zircon Hf and whole-rock Sr-Nd-Pb isotopic systematics combined with high La/Yb (> 10) and intermediate Th/Ta ratios, suggest that the parental magma of the AMGRS could have been derived from EM-I lithosphere mantle enriched by recycled Archean continent crustal materials, accompanied by some assimilation of lower crustal components. The malic to felsic compositions of the AMGRS are different from typical bimodal rocks formed in an anorogenic intra-continent rift setting, but resemble those emplaced during post-collisional/post-orogenic extensional tectonic setting. This is compatible with their age of < 1.85 Ga, indicating they postdate the continent-continent collision between the Western and Eastern blocks of the NCC at similar to 1.85 Ga. (c) 2007 Elsevier B.V. All rights reserved. 
zircon U-Pb chronology; in situ zircon Lu-Hf analysis; geochemistry; alkali granotoid; petrogenesis; post-collisional/post-orogenic; extension; Late Paleoproterozoic; North China Craton; nd isotopic constraints; u-pb geochronology; tectonic evolution; geological significance; extensional tectonics; crustal evolution; basement rocks; fuping complex; eastern block; central zone