Cookies

We use cookies to ensure that we give you the best experience on our website. You can change your cookie settings at any time. Otherwise, we'll assume you're OK to continue.

Durham University

Department of Earth Sciences

Profile

Publication details for Professor Yaoling Niu

Huang, X.L., Niu, Yaoling, Xu, Y.G., Yang, Q.J. & Zhong, J.W. (2010). Geochemistry of TTG and TTG-like gneisses from Lushan-Taihua complex in the southern North China Craton: Implications for late Archean crustal accretion. Precambrian Research 182(1-2): 43-56.

Author(s) from Durham

Abstract

The late Archean Taihua complex, mainly composed of amphibolite and TTG and TTG-like gneisses, is volumetrically most important metamorphic rock suites scattered along the southern margin of the North China Craton (NCC). Zircon SHRIMP U-Pb dating shows two episodes (2765 +/- 13 and 2723 +/- 9 Ma) of Archean magmatism in the Lushan area with distinct geochemical features. The early (2765 13 Ma) suite (TTG-like gneisses) has low-SiO2 (52.5-66.1 wt%), high-Mg-# (0.47-0.68), low HREE (Yb-N = 3.0-5.4) and Y(8.07-13.9 ppm) with low to moderate (La/Yb)(N) (6.7-37.1) and Sr/Y (25.9-119.3). The younger (2723 9 Ma) suite (TTG gneisses) has high-SiO2 (63.5-74.3 wt%), low-Mg-# (0.13-0.52), very low REE (Yb-N < 1.8) and Y (<4 ppm) with a wide range of (La/Yb)(N) (5.2-86.6), Sr/Y (71.4-949) and showing Eu/Eu* > 1 (1.20-2.43). Both suites show pronounced negative Nb-Ta and Ti anomalies on the primitive mantle-normalized spidergram. The TTG-like gneiss suite has similar bulk-rock Nd and zircon Hf model ages (similar to 3.0 Ga) with epsilon(Nd)(r)> 0 (0.26-1.46), and is interpreted as resulting from melt of mantle interactions with the melts derived from partial melting of subducted ocean crust with a residual assemblage of garnet+ clinopyroxene + rutile +/- amphibole, which favors subducted slab model for the late Archean TTG. The TTG gneiss suite has abundant relic zircons (2.95-2.80 Ga) with epsilon(Nd)(t)< 0 (-1.31 to -0.23), which is best interpreted as derived from partial melting of thickened lower continental crust with a garnet-amphibolite residue (garnet + amphibole rutile). Significant high-pressure fractional crystallization (garnet amphibole) and accumulation (plagioclase) are also required in the petrogenesis. The Lushan amphibolite with nearly flat primitive mantle-normalized trace-element pattern is interpreted to represent early ocean crust metamorphism. These observations suggest a possible model of late Archean crustal accretion from ocean crust to continental terrain in the southern North China Craton. (C) 2010 Elsevier B.V. All rights reserved.