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Wan Y.,Chinese Academy of Geological Sciences | Wan Y.,Beijing Center | Wan Y.,Curtin University Australia | Liu D.,Chinese Academy of Geological Sciences | And 9 more authors.
Journal of Asian Earth Sciences | Year: 2010

The Yunkai Terrane is one of the most important pre-Devonian areas of metamorphosed supracrustal and granitic basement rocks in the Cathaysia Block of South China. The supracrustal rocks are mainly schist, slate and phyllite, with local paragneiss, granulite, amphibolite and marble, with metamorphic grades ranging from greenschist to granulite facies. Largely on the basis of metamorphic grade, they were previously divided into the Palaeo- to Mesoproterozoic Gaozhou Complex, the early Neoproterozoic Yunkai 'Group' and early Palaeozoic sediments. Granitic rocks were considered to be Meso- and Neoproterozoic, or early Palaeozoic in age. In this study, four meta-sedimentary rock samples, two each from the Yunkai 'Group' and Gaozhou Complex, together with three granite samples, record metamorphic and magmatic zircon ages of 443-430 Ma (Silurian), with many inherited and detrital zircons with the ages mainly ranging from 1.1 to 0.8 Ga, although zircons with Archaean and Palaeoproterozoic ages have also been identified in several of the samples. A high-grade sillimanite-garnet-cordierite gneiss contains ∼242 Ma metamorphic zircons, as well as ∼440 Ma ones. Three of the meta-sedimentary rocks show large variations in major element compositions, but have similar REE patterns, and have tDM model ages of 2.17-1.91 Ga and εNd (440 Ma) values of -13.4 to -10.0. Granites range in composition from monzogranite to syenogranite and record tDM model ages of 2.13-1.42 Ga and εNd (440 Ma) values of -8.4 to -1.2. It is concluded that the Yunkai 'Group' and Gaozhou Complex formed coevally in the late Neoproterozoic to early Palaeozoic, probably at the same time as weakly to un-metamorphosed early Palaeozoic sediments in the area. Based on the detrital zircon population, the source area contained Meso- to Neoproterozoic rocks, with some Archaean material. Palaeozoic tectonothermal events and zircon growth in the Yunkai Terrane can be correlated with events of similar age and character known throughout the Cathaysia Block. The lack of evidence for Palaeo- and Mesoproterozoic rocks at Yunkai, as stated in earlier publications, means that revision of the basement geology of Cathaysia is necessary. © 2009 Elsevier Ltd.

Wan Y.,Chinese Academy of Geological Sciences | Wan Y.,Beijing Center | Liu D.,Chinese Academy of Geological Sciences | Liu D.,Beijing Center | And 10 more authors.
Precambrian Research | Year: 2011

The evolution of the North China Craton (NCC) is well known for a marked 2.55-2.50Ga tectonothermal event. However, supracrustal and intrusive rocks of 2.75-2.70Ga are in fact widely distributed in the western Shandong Province, the most important area of Archaean basement in the eastern part of the NCC. This paper reports SHRIMP U-Pb dating and LA-ICPMS Hf isotopic composition of zircons from 2.75-2.70Ga supracrustal and trondhjemite-tonalite-granodiorite (TTG) rocks in that area. Three fine-grained (hornblende) biotite gneiss samples (known locally as leptynite, with meta-volcanic or volcanosedimentary rock protoliths) and five TTG samples have SHRIMP zircon U-Pb ages varying from 2.75 to 2.70Ga and 2.74 to 2.71Ga, respectively. Zircons from most of the samples have high positive e{open}Hf(t) values (+4.7 to +10.0) and tDM(Hf) ages (2.85-2.60Ga) similar to their zircon U-Pb ages. This indicates that the rocks represent largely juvenile crustal additions derived from depleted mantle only a short time before. However, some granitoids show e{open}Hf(t) zircon values of -13.6 to +5.1 and tDM(Hf) of 3.51-2.80Ga. Therefore, the strong 2.75-2.70Ga tectonothermal event in the western Shandong Province involved not only juvenile addition to the continental crust but also intracrustal recycling of older components. Combined with craton-wide data, it is shown that the NCC is similar to many other cratons around the world where tectonothermal events of ∼2.7Ga are well developed. However, the main difference is that in the NCC, superimposed ∼2.5Ga tectonothermal events were much stronger than in most other cratons. © 2011 Elsevier B.V.

Wang W.,CAS Institute of Geology and Geophysics | Wang W.,Beijing Center | Wang W.,Wuhan University | Yang E.,Shandong Geological Survey Institute | And 8 more authors.
Precambrian Research | Year: 2013

Western Shandong Province (WSP) is one of the typical Neoarchean granite-greenstone belts in the North China Craton (NCC). The Taishan association, consisting of a ∼2.7Ga komatiite-tholeiite sequence and a ∼2.5Ga felsic volcanic-sedimentary sequence, is the major supracrustal assemblage in the WSP. The ∼2.7Ga komatiite-tholeiite sequence can be subdivided into the Yanlingguan and Liuhang units. The 150-800m thick basaltic lava sequence of the Liuhang unit is exposed in the Qixingtai area, with the bottom unit composed of massive and layered basalts. Pillow basalts and tuff dominate the upper parts of the sequence. We report a weighted mean SHRIMP 207Pb/206Pb zircon age of 2706±9Ma (MSWD=0.61) for a trondhjemitic dike that intrudes the base of the pillow basalts, constraining the timing of this sequence to be older than this age. The basaltic lava sequence in the Liuhang unit is characterized by voluminous tholeiites and a minor component of enriched basalts. The tholeiites show relatively high MgO (5.5-9.0wt.%), but low TiO2 (0.8-1.3wt.%) and Nb (2.1-3.3ppm) contents. They display co-variations between Zr and other immobile trace elements and flat REE and trace elements patterns on chondrite- and primary mantle-normalized diagrams, respectively. In contrast, the enriched basalts have low MgO (3.6-5.4wt.%), but high TiO2 (1.6-2.2wt.%) and Nb (8.4-11.6ppm) contents. They display moderately enriched LREE and fractionated HREE patterns on chondrite-normalized diagrams. The basaltic sequence of the Liuhang unit displays a moderate range of initial e{open}Nd (-0.1 to +3.0) values. The element concentration and Nd isotopes of tholeiitic rocks in the Liuhang unit are comparable with the contemporaneous tholeiites in greenstone belts globally. In particular, the geochemical systematics of the tholeiite and enriched basalts show close similarity with those of the Wawa greenstone belt in the Superior Province.The Nb/Th, La/Smcn and Nb/La ratios of these basalts indicate that the basaltic lava sequence of the Liuhang unit has not been significantly affected by crustal contamination compared to the Yanlingguan komatiite-tholeiite sequence. The variation in lithology and geochemistry of basalts between the Liuhang and Yanlingguan units reflects a lateral change in composition of the ∼2.7Ga basaltic eruption. We propose that the komatiite-tholeiite sequence in the Taishan association was derived from an upwelling mantle plume with eruption close to the continental margin within an ocean basin. Our study does not provide any evidence to support that the WSP granite-greenstone belt was subjected to significant arc-plume interaction during the early Neoarchean. Our results contribute to the understanding of early Neoarchean crustal growth globally identified from different regions. © 2012 Elsevier B.V..

Castro N.A.,Federal University of Ceará | Ganade de Araujo C.E.,University of Sao Paulo | Basei M.A.S.,University of Sao Paulo | Osako L.S.,Federal University of Ceará | And 2 more authors.
Journal of South American Earth Sciences | Year: 2012

We present field relationships, major and trace element geochemistry and U-Pb SHRIMP and ID-TIMS geochronology of the A-type Ordovician Quintas pluton located in the Ceará Central Domain of the Borborema Province, in northeastern Brazil. This pluton presents a concentric geometry and is composed mainly of syenogranite, monzogranite, quartz syenite to quartz monzodiorite, monzogabbro and diorite. Its geochemical characteristics [SiO 2 (52-70%), Na 2O/K 2O (1.55-0.65), Fe 2O 3/MgO (2.2-7.3), metaluminous to sligthly alkaline affinity, post-collisional type in (Y + Nb) × Rb diagram, and A-type affinity (Ga > 22 ppm, Nb > 20 ppm, Zn > 60 ppm), REE fractioned pattern with negative Eu anomaly] are coherent with post-collisional A 2-type granitoids. However, the emplacement of this pluton is to some extent temporally associated with the deposition of the first strata of the Parnaíba intracratonic basin, attesting also to a purely anorogenic character (A 1-type granitoid). The emplacement of this pluton is preceded by one of the largest known orogenesis of the planet (Neoproterozoic Pan-African/Brasiliano) and, if it is classified as an A 2-type granitoid, it provides interesting constraints about how long can last A 2-type magmatic activity after a major collisional episode, arguably triggered by disturbance of the underlying mantle, a topic extensively debated in the geoscience community. © 2011 Elsevier Ltd.

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.

Li Z.,Zhejiang University | Chen H.,Zhejiang University | Song B.,Beijing Center | Li Y.,Zhejiang University | And 2 more authors.
Journal of Asian Earth Sciences | Year: 2011

The temporal relations of different types of rocks in the Tarim large igneous province (TLIP) are studied using stratigraphic correlation, lithologically spatial distribution and isotopic ages. The TLIP covers an area >250,000km2 in the western and central part of the Tarim Basin. The lithological units of the TLIP include basalt, diabase, layered intrusive rock, breccia pipe mica-olivine pyroxenite, olivine pyroxenite, gabbro, ultramafic dyke, quartz syenite, quartz syenite porphyry and bimodal dyke. This is the first report for the spatial distribution of the TLIP from the spatial section lines, which shows the stratigraphic correlation among basaltic lava, tuff, interlayered mudstone, siltstone and sandstone and the thicknesses of the basaltic lavas from different field sections and drill holes, and the basalts from the Kupukuziman and Kaipaizileike Formations were subdivided in the drill hole sections. This indicates that the basaltic lavas were widely distributed in the Tarim Basin. Combined with previous study of geochemical and Sr-Nd-Pb isotopic characterization from the basalts and their genetic link with mantle plume activity, and large diabase swarms developments, the Permian igneous units constitute a Tarim large igneous province. Zircon SHRIMP U-Pb dating firstly yields 284.3±2.8Ma for the quartz syenite porphyry. Recent SHRIMP and LA-ICP-MS zircon U-Pb and 40Ar/39Ar ages are used to discuss temporal relations of different rock units in the TLIP formed between 290 and 274Ma, and these data are more reliable than the K-Ar ages of 220-310Ma reported previously. The sequence of magmatism of the TLIP in the central and western parts of the Tarim Basin are basaltic lava in the Kupukuziman and Kaipaizileike Formations (285-290Ma), layered mafic-ultramafic rock, mica-olivine pyroxenite breccia pipe, diabase and ultramafic dyke, quartz syenite, quartz syenite porphyry and bimodal dyke (274-284Ma). © 2011.

Wan Y.,Chinese Academy of Geological Sciences | Wan Y.,Beijing Center | Wan Y.,State Key Laboratory of Geological Process and Mineral Resources | Dong C.,Chinese Academy of Geological Sciences | And 13 more authors.
Precambrian Research | Year: 2012

At the end of the Neoarchean continental evolution, voluminous syenogranites were emplaced in the North China Craton, together with other magmatic rocks (trondhjemite-tonalite-granodiorite (TTG), monzogranite, diorite, gabbro). Syenogranites are widely distributed in Anshan-Benxi, Qinhuangdao and western Shandong, and also occur in southern Jilin, northern Liaoning, northwestern Hebei and central Henan. Based on geological relationships, degree of metamorphism, deformation and magmatic zircon ages, two phases of syenogranite magmatism are recognized. Rocks produced during the first phase show a gneissic texture and were formed between 2.53 and 2.52Ga and locally comprise abundant TTG. Rocks of the second phase cut late Neoarchean TTG and supracrustal rocks, display a massive structure, and mainly formed between 2.52 and 2.50Ga. All syenogranites share the same features in major element compositions, being high in SiO2 and low in CaO, total FeO, MgO, TiO2 and P2O5. However, they are different in trace and REE compositions and can be subdivided into three types. (1) Type 1 shows a large variation in total REE contents, low (La/Yb)n ratios, strong negative Eu*/Eu anomalies and Ba depletion; (2) Type 2 is similar to Type 1 but has higher (La/Yb)n ratios. (3) Type 3 shows a large variation in total REE and (La/Yb)n ratios and significantly do not show strongly negative Eu*/Eu anomalies and Ba depletion. Whole-rock Sm-Nd isotopic compositions show large variations in εNd(t) values and tDM(Nd) modal ages, ranging from -9.49 to -4.72 and 3.70 to 3.25Ga (Type 1), 0.55-1.03 and 2.77-2.71Ga (Type 2) and -2.35 to 1.23 and 2.93-2.66Ga (Type 3), respectively. Hf isotopic compositions of zircons from three samples have εHf(t) values and tDM1(Hf) ages of 0.7-7.2 and 2.84-2.56Ga (Type 1), 2.6-7.4 and 2.74-2.56Ga (Type 2) and 2.1-6.3 and 2.76-2.60Ga (Type 3). It is concluded that syenogranites were generated by melting of continental crust with different mean crustal residence ages, and most of them were emplaced during the second phase (2.52-2.50Ga) in an extensional tectonic regime. The formation of these voluminous syenogranites marks a tectono-magmatic event resulting in stabilization of the North China Craton at the end of the Neoarchean. © 2011 Elsevier B.V.

Du L.,Chinese Academy of Geological Sciences | Yang C.,Chinese Academy of Geological Sciences | Ren L.,Chinese Academy of Geological Sciences | Song H.,Chinese Academy of Geological Sciences | And 3 more authors.
Acta Petrologica Sinica | Year: 2012

Paleoproterozoic magmas are widely distributed in Ltiliang Mountains, and the petrogenesis and tectonic setting of these magmas are significant for reshaping the geological evolution of the North China Craton. In this paper, we report Dujiagou feldspar porphyrite, intermediate basic volcanic rocks from the Jinzhouyu Formation of the Ltiliang Group and Ehutan gneiss in Ltiliang Mountains. SHRIMP U-Pb zircon dating of two Dujiagou feldspar porphyrite samples yield the ages of 2189 ±6Ma and 2186 ± 3Ma, respectively, and one Ehutan dioritic gneiss sample gets a SHRIMP U-Pb zircon age of 2182 ±5Ma. Dujiagou feldspar porphyrites show the characteristics of A-type granite formed in a post orogenic setting. While, intermdiate basic volcanic rocks in the Jinzhouyu Formation and Ehutan gneisses have the characteristics of volcanic rocks formed in island arc setting. Considering the tectonic setting of 2. 2 ∼2. OGa magmatic events in the North China Craton, the formation of the 2. 2 ∼ 2. IGa magmatic rocks is probably related to its tectonic position during the Paleoproterozoic, with Ltiliang Mountains being located at the margin of the North China Craton. The 2. 2 ∼ 2. IGa magmatic rocks in the study area were formed in both island arc and rift regimes at about same time.

Wan Y.,Chinese Academy of Geological Sciences | Wan Y.,Beijing Center | Wan Y.,State Key Laboratory of Geological Process and Mineral Resources | Liu D.,Chinese Academy of Geological Sciences | And 10 more authors.
Gondwana Research | Year: 2011

The North China Craton (NCC) was subjected to an extensional regime after the Lüliang movement at ~1.8Ga and then was covered by an extensive Meso- to Neoproterozoic sedimentary succession, namely the Changcheng, Jixian and Qingbaikou Groups in ascending order. We report age spectra for detrital zircons and monazites, Hf isotopic systematics of detrital zircons, and whole-rock chemical and Nd isotopic compositions for sediments from the succession in the Ming Tombs area, Beijing, one of the typical Meso- to Neoproterozoic areas in the NCC. Detrital zircons of six sedimentary samples have two distinct age peaks at ~2.52Ga and ~1.85Ga. There are some detrital zircons at 2.4-2.0Ga but none at 2.3Ga and only a few >2.7Ga. The detrital zircon age spectra change with time. Sediments in the lower succession (Changcheng Group) and in the upper successions (Jixian and Qinbaikou Groups) are dominated by significant detrital zircon populations of late Neoarchean and late Paleoproterozoic ages, respectively. The ~2.5Ga detrital zircons of the Changcheng Group have εHf(2.5Ga) values and tDM(Hf) model ages mainly ranging from -2 to +7 and 2.8 to 2.7Ga, respectively. Detrital monazites of a sample from the Jixian Group exhibit a major age peak between 1.95 and 1.80Ga with some data between 2.0 and 1.95Ga. The sedimentary rocks of the Changcheng Group are characterized by high K2O contents (mostly 7.09-15.20%) and insignificant Eu anomalies (Eu/Eu*=0.71-1.16). They have tDM(Nd) model ages ranging from 2.70 to 2.43Ga, being older than the tDM(Nd) ages (2.11 and 1.99Ga) of sedimentary samples from the Qingbaikou Group. Based on a comparison with ages for the early Precambrian (>1.8Ga) basement of the NCC, it can be concluded that (1) the sediments of the Meso- to Neoproterozoic cover were undoubtedly derived from the NCC itself or once neighboring terranes; (2) variations in the detrital zircon age spectra from the lower to the upper successions reflect provenance evolution in that the lower crustal late Paleoproterozoic rocks were exposed at the surface after the upper crustal late Neoarchean rocks had already been eroded. © 2011 International Association for Gondwana Research.

Gao L.-Z.,Chinese Academy of Geological Sciences | Wang Z.-Q.,Chinese Academy of Geological Sciences | Xu Z.-Q.,Chinese Academy of Geological Sciences | Yang J.-S.,Chinese Academy of Geological Sciences | Zhang W.,Beijing Center
Geological Bulletin of China | Year: 2010

Neoproterozoic glaciations of Quruqtagh area in Tarim basin are recognized, four of which appear to be global and with different volcanic rocks. In recent years, "Snow earth" hypothesis put forwards to the study of glaciation, any advancement of sedimentary, depositional environment and glaciation chronostratigraphic dating for the four glaciations in Quruqtagh area in Tarim basin, which will put more attention to global. This paper gives a new zircon SHRIMP U-Pb dating to be showing an evidence for the Neoproterozoic glaciations of Quruqtagh area in Tarim basin.

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