U-Pb Zircon Dating of the Granitic Conglomerates of the Hutuo Group： Affinities to the Wutai Granitoids and Significance to the Tectonic Evolution of the Trans-North China Orogen

1 Introduction The North China Craton (NCC) is considered to be the oldest and largest cratonic block in China. Recent studies to gain understanding of basement architecture of the NCC has led to its division into the Western and Eastern Blocks, separated by a N-S trending Paleoproterozoic Trans-North China Orogen (TNCO) (Fig. 1; Zhao et al., 1998, 1999a, 2000a, 2001a; Wilde et al., 2002). Although there is now abroad consensus that the final assembly of the NCC was completed by th…     

Nd-Sr Isotopic Geochemistry of the Late Archean-Paleoproterozoic Granitoids in the Lüliang-Wutai Terrain,North China Craton,and Implications for Petrogenesis

1 Introduction The tectono-thermal evolution of the North China Craton (NCC) in Late Archean to Paleoproterozoic times has long been attractive to many researchers (Wan et al., 2000; Zhao et al., 2000, 2002; Guo et al., 2001; Liu et al., 2002; Zhai and Liu 2003; Zhai, 2004; Yu et al., 2004; Kr?ner et al., 2005; Wilde et al., 2005). Zhao et al. (2000, 2002) proposed a tectono-thermo framework for the evolution of the NCCbased on detailed petrological and geochronological data, and they …     

New Discovery of ~1866 Ma High-temperature Mylonite in the Helanshan Complex: Marking a Late-stage Ductile Shearing in the Khondalite Belt, North China Craton

正Objective The Khondalite Belt is a nearly E–W-trending Paleoproterozoic Himalayan-type orogen in the Western Block of the North China Craton. It is regarded as a result of the collision between the northern Yinshan Block and the southern Ordos Block at ～1.95 Ga, which led to the formation of the united basement of the Western Block(e.g., Zhao et al., 2005; Yin et al., 2011). The Khondalite Belt has undergone long-term continent-continen collisional orogenic processes, and a remarkable series of late-stage orogen-parallel ductile shear zones developed(e.g., Huang et al., 2013; Gong et al., 2014).     

Report on 34 Ga SHRIMP Zircon Age from the Yuntaishan Geopark in Jiaozuo, Henan Province

1 Introduction According to recent researches, the North China Craton consists of three parts: the eastern block, western block and central zone (Zhao, 2001; Wilde et al., 2002). Paleoarchean continental blocks and zircon residuals have only been found in a few regions, such as Anshan, East Liaoning (Liu et al., 1992; Song et al., 1996; Wan et al., 2002, 2005), Caozhuang, East Hebei (Liu et al., 1992) and Xinyang, West Henan (Zheng et al., 2004), which are mainly distributed in the east…     

Carboniferous foraminifers from the lower part of Paleo-Tethyan seamount-type carbonates in the Changning-Menglian Belt, western Yunnan, Southwest China

The Changning-Menglian Belt in West Yunnan, Southwest China is well-known as a closed remnant of the Paleo-Tethys Ocean in East Asia (Wu et al., 1995; Liu et al., 1996). It is delineated to the east with the Lincang Massif by the Changning-Shuangjiang Fault and to the west with the Baoshan Block by the Kejie-Nandinghe Fault, and is generally subdivided into three zones: east, central, and west zones. In the central zone, various kinds of oceanic rocks such as harzburgite, cumulate websterite, gabbro, both mid-oceanic ridge basalt and oceanic island basalt, Devonian-Triassic radiolarian chert, and Carbonifer-ous-Permian massive and huge carbonates with basaltic effusives as their pedestal are exposed (Liu et al., 1991, 1996; Wu et al., 1995; Ueno et al., 2003). These Central zone rocks are now interpreted to have been emplaced as nappes structurally overlying the East and West zones, which are considered as consisting mainly of passive margin sediments of the Baoshan Block (Wu, 1991; Ueno et al., 2003).     

Precambrian Captured Zircon Ages in the Daheigou Formation, Xing’an Block

正Objective The Xing'an Block(XB) is located between the Erguna Block(EB) and the Songnen Block(SB), which topographically occupies the northeastern half of the Great Xing'an Range(Liu et al., 2017). The XB was traditionally considered to be composed of a Precambrian metamorphic basement and post-Cambrian cover. However, the recent geochronological studies show that the so-called "Precambrian metamorphic rocks" are much     

GEOCHEMISTRY OF VOLCANIC ROCKS FROM WULIBA IN THE MIANLUE SUTURE ZONE, SOUTHERN QINLING

1. IntroductionThe Mianlue (Mianxian-Lueyang) suture zone is one of the components of the Qinling orogenic belt and the latest major suture zone between North and South China. The data available suggest that it is a complicated ophiolitic tectonic melange zone including many tectonic slabs of different origins (Zhang et al., 1995; Lai et al., 1996; Lai et al.,1997; Lai et al.,1998; Xu et al.,1996). Up to now, however, there is not definite evidence of volcanic rock assemblage and geochemi…     

The Cu-Mo Mineralization of the Late Jurassic Porphyry in the Northern Great Xing’an Range: Constraints from Zircon U-Pb Ages of the Ore-Causative Granites

The Great Xing’an Range(GXAR)is one of the most important metallogenic belts in China.Previous study has shown that porphyry Cu-Mo deposit distributed in the northern Great Xing’an Range formed mainly in two stages:(1)Early Ordovician,such as Duobaoshan and Tongshan deposits(Liu et al.,2017);2)Triassic-Early Jurassic,including Wunugetushan,Taipingchuan and Badaguan deposits(Tang et al.,2016).In recent years,two potential porphyry Cu-Mo deposits,Huoluotai and Xiaokele,were discovered in the Erguna Block,northern GXAR(Figs.1a–b).However,the ore formation ages and regional metallogenic regularity are ambiguous due to the lack of isotopic ages.Two zircon U-Pb ages from the ore-causative granites were reported in this paper,with the aims to constrain the metallogenic ages and provide evidence for study of the regional metallogenic regularity and ore prospect prediction.     

The Gaojiacun Mafic-Ultramafic Complex （Sichuan, SW China）：Neoproterozoic Magmatic Activity at the Western Margin of the Yangtze Craton

1 Introduction The Gaojiacun intrusive complex is one of the numerous ultramafic-mafic intrusions in Sichuan Province of China. It was mapped during the 1970s and studied mainly by Chinese scientists (e.g. Geological Team 106, 1975; Shen et al., 1986, 1989; CGGJC, 1986; Yang et al., 1993; Li et al., 1995; Shen et al., 2003; Zhu et al., 2004a). Since the year 2000, China has become one of the largest PGE consumers. While the country can produce only less than 1 ton PGE/year, the Chin…     

A Combined-Power Model for the Distribution of Axial Force in Shaft Anchor along Its Length

INTRODUCTIONThe anchorage of geomaterial , including shaftanchors and prestressed tendons ,is usually used ingeotechnical engineering. Owing to various advanta-ges ,these two anchorage types are widely used instructures in China ( Cao et al ., 2003 ; Fu et al .,1999 ;Lu et al .,1998 ; Li et al .,1995) . Shaft an-chors can be classifiedinto three kinds by the forceinthe shaft and cement grout :tensile ,press ,and sheartype (Lu et al .,1998) . The tensile type is the mostpopular in China…     

内蒙古大青山地区古元古代花岗岩:地球化学、锆石SHRIMP定年及其地质意义

内蒙古大青山地区沿固阳-武川断裂带南侧发现一条古元古代花岗岩岩带,由石英闪长岩-闪长岩-角闪二长花岗岩组合构成.本文对其中典型代表厂汉脑包石英闪长岩、常福龙闪长岩和口子村角闪二长花岗岩进行了锆石定年和地球化学研究.地球化学上,石英闪长岩具有埃达克质花岗岩的特点,为低硅埃达克质花岗岩;大部分闪长岩具有赞岐岩的地球化学特征,部分具Closepet花岗岩特征;角闪二长花岗岩则全部具有Closepet花岗岩特征.根据锆石SHRIMP U-Pb定年,它们形成于2416~2435Ma之间,并遭受古元古代晚期构造热事件改造.表明在该区古元古代早期真正意义的板块构造已起作用,从岩浆演化的角度说明前寒武纪构造体制发生重大转变.     

The Sarcheshmeh porphyry copper deposit,Kerman, Iran: A mineralogical analysis of the igneous rocks and alteration zones including halogen element systematics related to Cu mineralization processes

The giant Sarcheshmeh porphyry Copper deposit is located 65 km southwest of Kerman City, southeastern Iran. Numerous Miocene porphyry stocks and dykes intruded thick sequences of Upper Cretaceous sedimentary and Eocene volcanic rocks. Hypogene and supergene porphyry Cu mineralization occurs within the granodioritic porphyry and host rock sequence, which was extensively altered to a dominantly potassic, phyllic, and argillic assemblage with interstitial to distal propylitic types.Biotite-bearing assemblages occur as both primary phenocrysts and secondary replacements showing variable size, colour, and shape. Fluorine contents (0.22 to 1.33 wt.%) and X_Mg (0.54 to 0.71) in biotites from the potassic and phyllic zones are higher than those of non-mineralized granitoids (F = 0.09 to 0.56 wt.%, X_Mg = 0.43 to 0.54), whereas their Cl contents (Cl = 0.05 to 0.24 wt.%) are lower than those of the non-mineralized granitoids (Cl = .0.11 to 0.45). The biotites from the phyllic zone have higher log (fH₂O/fHF) and log (fH₂O/fHCl) values than those of the potassic zone, as well as the granitoid and andesitic dykes. The log (fHF/fHCl) values determined for the granitoid, potassic and phyllic zones are similar, though more negative than those of the andesitic dykes. The log (fHF/fHCl) values have a similar range for biotite from the granitoid, and potassic and phyllic zones. The halogen fugacity ratios established for fluids associated with the Sarcheshmeh deposit from their F and Cl contents in biotite show that the granitoid, potassic zone and phyllic zone are increasingly affected by meteoric waters. The fluids that circulated in the phyllic zone are predominantly of meteoric origin, possibly overprinting original phyllic zone halogen contents.The Cl intercept values of biotite in the granitoid, and phyllic and potassic are similar to other ore-forming systems and tend to be more Cl-rich than Cl-intercept values of biotites in common igneous rocks. Calculated F/Cl intercept values for biotite in the granitoid and potassic zone are also consistent with many other porphyry copper forming systems.     

Preservation of a Paleoproterozoic rifted margin in the Himalaya:Insight from the Ulleri-Phaplu-Melung orthogneiss

Orthogneiss within the Paleoproterozoic strata of Lesser Himalayan sequence across the Himalaya has been variably linked to development in a continental arc setting, Indian basement, or a continental rift.New whole rock and trace element geochemical data and U/Pb zircon geochronology indicate that the granitoid protoliths to these rocks were derived from upper crustal sources in the Paleoproterozoic and have within-plate, A-type affinities. This is consistent with their generation in a rifted margin and is compatible with paleogeographic reconstructions that indicate an open boundary for present-day northern India in the Paleoproterozoic.     

Late Paleoproterozoic basic dikes in the Ulkan-Uchur district, eastern Aldan-Stanovoi Shield: Structural position, composition, and paleogeodynamic setting

Late Paleoproterozoic dikes of the Maimakan Complex were studied in the Ulkan-Uchur district at the eastern margin of the Aldan-Stanovoi Shield. The dikes are parallel or arranged en echelon in the Uchur-Uyan, South Uchur, and Ukikan fields of dike swarms. The spatial distribution of the dike swarms pertaining to the Maimakan Complex in the Ulkan Trough and its framework shows that the area of their intersection is located in the center of the Ulkan granitoid batholith. The basic dikes, which are distinguished by elevated contents of alkali metals, Fe, Ti, and P in combination with a low Mg content, are defined as moderately alkaline rocks transitional from tholeiitic to alkaline series similar in composition to within-plate basalts and E-MORB. The REE pattern is comparable to that of tholeiitic and subalkaline series in extensional settings. Along with the geological data, this indicates that the complex was formed under conditions of intracontinental extension. As follows from geological relationships, the age of dikes is estimated as 1670–1715 Ma.     

白云鄂博地区早前寒武纪基底岩浆作用和变质作用:锆石SHRIMP U-Pb定年和LA-MC-ICPMS Hf同位素分析

白云鄂博位于华北克拉通北缘,是阴山地块的重要组成部分。本文对该区变质基底的5个花岗质岩石样品进行了锆石SHRIMP U-Pb定年,获得了2.63Ga和1.89~2.20Ga的岩浆锆石年龄以及2.47~2.51Ga和1.86~1.94Ga的变质锆石年龄。新太古代早期片麻状英云闪长岩的岩浆锆石ε_Hf(t)值和t_DM2(CC)(Hf)年龄分别为3.57~8.36和2.59~2.88Ga,古元古代中晚期花岗质岩石的岩浆锆石ε_Hf(t)值和t_DM2(CC)(Hf)年龄分别为-17.20~8.58和2.11~3.70Ga。变质锆石与岩浆锆石具有类似的Hf同位素组成。结合前人研究成果,表明:白云鄂博地区存在新太古代早期到古元古代晚期岩浆作用;在每一岩浆作用过程中,地幔添加和壳内再循环都起了重要作用;白云鄂博地区变质基底经历了新太古代晚期-古元古代早期和古元古代晚期构造热事件;阴山地块与南侧孔兹岩带具有类似的早前寒武纪地质演化历史。     

山西吕梁群和其主变质作用的锆石U-Pb年龄

本文用单颗粒锆石U-Pb定年方法对山西吕梁群的火山岩和宽坪村的花岗质混合片麻岩进行了年代学研究。吕梁群上部的双峰式火山岩喷发于大约2100Ma前,表明吕梁群形成于早元古代。而其主变质作用发生在早元古代晚期,即1806Ma左右。     

陕西柞山盆地池沟铜钼矿区含矿岩体的锆石U-Pb年龄和岩石成因

秦岭造山带柞山盆地多处发育与晚中生代中酸性小岩体有关的铜钼矿床(点),最近在池沟深部发现了厚大的斑岩型铜矿体,但对这些小岩体的形成时代和成因的研究很少。本文选择池沟地区不同类型的花岗质岩石开展地球化学特征和锆石U-Pb测年的研究。结果表明:该区小岩体主要为闪长岩、石英闪长岩和斑状花岗岩,它们为钾质钙碱性Ⅰ型花岗质岩石。矿物学、地球化学和Sr-Nd同位素特征均暗示它们是上地幔和下地壳同熔的深熔岩浆产物。与成矿密切相关的含矿岩体LA-MC-ICPMS锆石U-Pb谐和年龄为~145Ma,结合区域地质资料和成岩成矿关系的研究,认为池沟含矿岩体形成于晚侏罗世-早白垩世,柞水盆地存在一期重要的晚侏罗世-早白垩世中酸性岩浆岩和相应的斑岩-矽卡岩铜钼金矿化,与华北地块南缘晚中生代岩体和相关的钼铅锌矿床形成于同一地质事件。     

Age and geochemistry of the granitoid from the Lunte area,Northeastern Zambia: Implications for magmatism of the Columbia supercontinent

The Paleoproterozoic tectonic evolution of the Bangweulu Block has long been controversial. Paleoproterozoic granites consisting of the basement complex of the Bangweulu Block are widely exposed in northeastern Zambia, and they are the critical media for studying the tectonic evolution of the Bangweulu Block. This study systematically investigated the petrography, zircon U-Pb chronology, and petrogeochemistry of the granitoid extensively exposed in the Lunte area, northeastern Zambia. The results show that the granitoid in the area formed during 2051±13–2009±20 Ma as a result of Paleoproterozoic magmatic events. Geochemical data show that the granites in the area mainly include syenogranites and monzogranites of high-K calc-alkaline series and are characterized by high SiO₂ content (72.68% –73.78%) and K₂O/Na₂O ratio (1.82–2.29). The presence of garnets, the high aluminum saturation index (A/CNK is 1.13–1.21), and the 1.27%–1.95% of corundum molecules jointly indicate that granites in the Lunte area are S-type granites. Rare earth elements in all samples show a rightward inclination and noticeably negative Eu-anomalies (δEu = 0.16–0.40) and are relatively rich in light rare earth elements. Furthermore, the granites are rich in large ion lithophile elements such as Rb, Th, U, and K and are depleted in Ba, Sr, and high field strength elements such as Ta and Nb. In addition, they bear low contents of Cr (6.31×10⁻⁶–10.8×10⁻⁶), Ni (2.87×10⁻⁶–4.76×10⁻⁶), and Co (2.62×10⁻⁶–3.96×10⁻⁶). These data lead to the conclusion that the source rocks are meta-sedimentary rocks. Combining the above results and the study of regional tectonic evolution, the authors suggest that granitoid in the Lunte area were formed in a tectonic environment corresponding to the collision between the Tanzania Craton and the Bangweulu Block. The magmatic activities in this period may be related to the assembly of the Columbia supercontinent.©2021 China Geology Editorial Office.     

朝鲜狼林地块东南缘太古宙岩石及其对古元古代构造热事件的响应

朝鲜狼林地体是中朝克拉通的重要组成部分,其早前寒武纪基底岩系的岩石组成、形成和变质作用时代,直接影响到人们对古元古代辽吉活动带乃至整个华北克拉通地质演化历史的理解和认识。本文选取位于狼林地块东南缘,狼林群变质杂岩中的3个花岗片麻岩样品进行锆石U-Pb定年分析。锆石的LA-ICPMS和SIMS定年结果显示,3个片麻岩原岩的岩浆结晶时代为2521~2567Ma,并且它们都经历了古元古代1.87~1.89Ga的构造热事件改造,表现为原始岩浆锆石不同程度的铅丢失以及变质锆石的形成。基于这一认识,并结合其他学者的最新研究结果可知,太古宙片麻岩存在于狼林地块平南盆地的南缘和东缘地区,由此推测狼林地块太古宙基底岩系的规模可能远大于目前所识别的这几个地区。这些太古宙片麻岩普遍遭受了古元古代强烈变质作用(深熔作用)改造,并且变质作用的时代可以与华北克拉通三条古元古代活动带的变质-深熔作用时代相对比,表明狼林地块可能至少在古元古代之前,就已经与华北克拉通组成了统一的大陆。     

Geochronology of the Xiaodonggou Porphyry Mo Deposit in Northern Margin of North China Craton

The Xiaodonggou porphyry Mo deposit is located in the Mesozoic calc-alkaline Xiaodonggou granitoid within a Palaeozoic fold zone of northern China. The mineralization mainly occurred in an area of 0.54 km² at the south-eastern part of the Xiaodonggou granitoid. The mineralization includes disseminated molybdenite, pyrite, chalcopyrite, magnetite and pyrrhotite and stockwork quartz-sulfide veins. A molybdenite-rich inner core is surrounded by a concentric zone of the sulfide mineral assemblage of pyrite, galena and sphalerite. Intense potassic alteration is overprinted by sericitization and silicification in the mineralized zone. SHRIMP U-Pb data of zircon indicate that the granitoid crystallized at 142 ± 2 Ma (2σ). Re–Os age dating for six molybdenite samples from underground galleries of the deposit constrains the age of porphyry-style Mo mineralization to be 138.1 ± 2.8 Ma (2σ). These data suggest that porphyry-style mineralization was associated with the Xiaodonggou granitoid intrusion and support an Early Cretaceous porphyry-type metallogenic epoch along the northern margin of North China Craton.