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Feng Y.-F.,Beijing University of Technology | Deng J.-F.,Beijing University of Technology | Wang S.-J.,Shandong Geological Survey | Xiao Q.-H.,Beijing University of Technology | And 8 more authors.
Geology in China | Year: 2010

Based on 39 SHRIMP and LA-ICP-MS Zircon U-Pb ages, 192 petrochemical data, and two representative age frameworks, this paper suggests a preliminary scheme of the age framework for the early Precambrian granites in western Shandong Province, i.e., three stages of (1)early-middle Neoarchean (2741-2612 Ma), (2)Late Neoarchean (2563-2500 Ma), and (3)early Paleoproterozoic (2494-2435 Ma), which correspond to three rock assemblages and the evolutional trends of (1)T1T2G1 with trondhjemitic trend, (2) T 1T2G1G2QM with both trondhjemitic and cale- alkahne trends, (3)G2QM with cale-alkaline trend. On the basis of both SiO2-MgO and SiO2-FeO/MgO relations, most of T1T2G1 having the magnesian andesitic rock (MA) characteristics is considered to have been formed in the oceanic subduction setting. It is thought that three stages of granitic rock assemblages might have been formed in island-arc, continental marginal arc, and continental collisional settings, respectively, and probably represented the compositions of immature, semi-mature, and mature continental crust, respectively. Thus, the granitic rocks have recorded the process of the formation of the continental crust.


Wan Y.,Chinese Academy of Geological Sciences | Liu D.,Chinese Academy of Geological Sciences | Dong C.,Chinese Academy of Geological Sciences | Liu S.,Chinese Academy of Geological Sciences | And 2 more authors.
Geoscience Frontiers | Year: 2011

This paper carried out a study on U-Th-Pb behavior of zircons in a "dry" rock system during high-grade metamorphism in the Archean basement of eastern Shandong. The studied sample has a mineral assemblage of plagioclase + K-feldspar + clinopyroxene + biotite + quartz and its protolith is considered to be diorite. The zircons are stubby, equant or irregular in shape and show fir-leaf, sectorial, banded or oscillatory zoning. They contain inclusions, including mineral assemblages of clinopyroxene + orthopyroxene + hornblende + quartz and plagioclase + K-feldspar + biotite + quartz. Fifty SHRIMP analyses were performed on 34 zircon grains, which commonly yielded high Th/U ratios (mostly >0.5). Most analyses are distributed along concordia from 2.54 to 2.25 Ga, with the youngest age being ∼1.95 Ga. Compositions and ages show large variations even in a same zircon grain. Combined with early studies, conclusions can be drawn as follows: 1) the diorite underwent two episodes of high-grade metamorphism, at the end of the Neoarchean and the Paleoproterozoic (∼2.50 Ga and ∼1.95 Ga or slightly later); 2) high-grade metamorphism in a "dry" rock system may partially reset the U-Th-Pb system of zircons and, in this case, the ages between the oldest and youngest are chronologically meaningless; and 3) high Th/U ratios may be common features of zircons formed during high-grade metamorphic conditions. © 2011, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.


Wan Y.,Chinese Academy of Geological Sciences | Wan Y.,Beijing Center | Wang S.,Shandong Geological Survey | Liu D.,Chinese Academy of Geological Sciences | And 13 more authors.
Gondwana Research | Year: 2012

Western Shandong Province is an important terrane in the eastern part of the North China Craton where 2.75-2.5. Ga tectono-thermal events are well recognized. Supracrustal rocks, named the Taishan "Group", experienced greenschist- to amphibolite-facies metamorphism and occur as lenses and strips in granitoids and are subdivided into the Yanlingguan, Shancaoyu and Liuhang "Formations". The Yanlingguan "Formation" is mainly composed of amphibolite but also contains fine-grained biotite-hornblende gneiss, komatiitic rocks and schist. The Liuhang "Formation" is similar in rock association to the Yanlingguan "Formation" but contains more metasedimentary rocks. The Shancaoyu "Formation" is mainly composed of fine-grained biotite gneiss (leptynite) preserving bedding and is interlayered with schist. Its protoliths are mainly sedimentary rocks with some mafic to felsic volcano-sedimentary varieties. We undertook SHRIMP zircon dating on eighteen metasedimentary and volcanic samples, mainly from the Shancaoyu "Formation" and the upper part of the Liuhang "Formation". Ages of detrital and volcanic zircons vary from 2.75 to 2.54. Ga and 2.55 to 2.525. Ga, respectively, and the age distribution patterns vary in different samples. We conclude that the Shancaoyu "Formation" and the upper part of the Liuhang "Formation" were deposited in the late Neoarchean (2.55-2.525. Ga) and not in the early Neoarchean (2.8-2.7. Ga) as thought before. Western Shandong is the only terrane in the North China Craton where both early and late Neoarchean supracrustal rocks have been identified. A magmatic arc model may be applied to explain the tectono-thermal evolution at the end of the Neoarchean. © 2011 International Association for Gondwana Research.


Zhang G.-H.,Chinese Academy of Geological Sciences | Fei Y.-H.,Chinese Academy of Geological Sciences | Yang L.-Z.,Shandong Geological Survey | Liu Z.-P.,Chinese Academy of Geological Sciences | Lian Y.-L.,Chinese Academy of Geological Sciences
Shuikexue Jinzhan/Advances in Water Science | Year: 2010

In order to understand the exploitation yield formation in the North China Plain with problems of intensive overexploitation, a study is conducted using the field data collected from borehole geophysical logs with deep groundwater depression cone located in the Dezhou region. The data collection includes groundwater sampling and dynamic monitoring, as well as land subsidence monitoring in the region. Both elastic release of water from sandy materials and water released through aquifer compression in the confined aquifer are calculated for both rate and intensity in different soil layers and partition zones, together with latter flow and aquifer recharge due to groundwater exploitation. Results show both elastic release of water and water released through aquifer compression are inconstant due to the intensive overexploitation effect on confined aquifers, which increase with the drop of deep groundwater levels. The longer the intensive overexploitation of groundwater and the closer to the centre of deep groundwater depression cone are, the higher the clay soil component in confined aquifers will be, as well as the greater the elastic release of water and the water released through aquifer compression are. The calculated composition of elastic release of water varies from 14.2% to 17.5%, and the portion of water released through aquifer compression is from 35.5% to 61.9% and closely related to the condition of land subsidence in the region.

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