Paleoproterozoic Granitoids on Liaodong Peninsula,North China Craton

Paleoproterozoic granitoids are an important constituent of the Jiao–Liao–Ji Belt(JLJB). The spatial-temporal distribution and types of Paleoproterozoic granitoids are closely related to the evolution of the JLJB. In this paper, we review the field occurrence, petrography, geochronology, and geochemistry of Paleoproterozoic granitoids on Liaodong Peninsula, northeast China. The Paleoproterozoic granitoids can be divided into pre-tectonic(～2.15 Ga; peak age=2.18 Ga) and post-tectonic(～1.85 Ga) granitoids. The pre-tectonic granitoids are magnetite and hornblende–biotite monzogranites and granodiorites. Pre-tectonic monzogranites are widespread in the JLJB and have A_2-type affinities. In contrast, pretectonic granodiorites are only present in the Simenzi area and have adakitic affinities. The post-tectonic granitoids consist of porphyritic monzogranite, syenite, diorite, granodiorite, quartz monzonite, monzogranite, and granitic pegmatite, which are adakitic rocks and I-, S-, and A_2-type granitoids. The assemblage of pre-tectonic A_2-type granitoids and adakitic rocks indicates the initial tectonic setting of the JLJB was a continental back-arc basin. The assemblage of post-tectonic adakitic rocks and I-, S-, and A_2-type granitoids indicates a post-collisional setting. The 2.20–2.15 Ga A_2-type granitoids and adakitic rocks were associated with the initial stage of back-arc extension, and the peak of back-arc extension is inferred from the subsequent(2.15–2.10 Ga) mafic intrusive activity. The ～1.90 Ga adakitic rocks mark the beginning of the postcollisional stage, which was followed by the intrusion of low-temperature S-and I-type granitoids. High-to low-pressure granitoids(S-type) were generated during the peak of post-collisional lithospheric delamination and asthenospheric upwelling. The emplacement of later granitic pegmatites occurred during the waning of the orogeny.     

Intrusion-Related Gold Deposits of North China Craton, People's Republic of China

Abstract. Intrusion‐related gold deposits are widely distributed within the North China craton or along its marginal fold belts. Presently, about 200 individual intrusion‐related gold deposits (prospects) have been discovered, among which Yuerya, Anjia‐yingzi, Linglong, Jiaojia, Chenjiazhangzi, Qiyugou, Jinjiazhuang, Dongping, Hougou, Huangtuliang, Guilaizhuang, Wulashan and Donghuofang are the most important ones. In general, the intrusion‐related gold deposits can be classified into three major groups according to their host rocks: (1) hosted by or related to felsic intrusions, including (la) calc‐alkaline granitoid intrusions and (lb) cryptoexplosion breccia pipes; (2) related to ultramafic intrusions, and (3) hosted by or related to alkaline intrusions. The first group contains the Yuerya, Anjiayingzi, Linglong, Jiaojia, Chenjiazhangzi and Qiyugou gold deposits. Gold mineralization at these deposits occurs within Mesozoic Yanshanian calc‐alkaline granitoid intrusions or cryptoexplosion breccia pipes as gold‐bearing quartz veins and replacement bodies. Pyrite, galena, sphalerite, chalcopyrite, native gold and electrum are major metallic minerals. The Jinjiazhuang deposit belongs to the second group, and occurs within Hercynian diopsidite and peridotite as quartz veins and replacement bodies. Pyrite, marcasite, arsenopyrite, native gold and electrum are identified. The third group includes the Dongping, Hougou, Huangtuliang, Guilaizhuang, Wulashan and Donghuofang deposits. Gold mineralization at these deposits occurs predominantly within the Hercynian alkaline intrusive complexes as K‐feldspar‐quartz veins and replacement bodies. Major metal minerals are pyrite, galena, chalcopyrite, tellurides, native gold and electrum. All these pyrite separates from Hercynian and Yanshanian intrusions or cryptoexplosion pipes associated with the gold deposits show a broad range in δ³⁴S value, which is overall higher than those Precambrian rocks and their hosted gold deposits. For the alkaline intrusion‐related gold deposits, the δ³⁴S values of the sulfides (pyrite, galena and chalcopyrite) from the deposits increase systematically from orebodies to the alkaline intrusions. All of these intrusion‐related gold deposits show relatively radiogenic lead isotopic compositions compared to mantle or lower crust curves. Most lead isotope data of sulfides from the gold ores plot in between the fields of the intrusions and Precambrian metamorphic rocks. Data are interpreted as indicative of a mixing of sulfur and lead from magma with those from Precambrian metamorphic rocks. Isotopic age data, geological and geochemical evidences suggest that the ore‐forming materials for the intrusion‐related gold deposits were generated during the emplacement of the Hercynian or Yanshanian intrusion. The calc‐alkaline or alkaline magma may provide heat, volatiles and metals for the intrusion‐related gold deposits. Evolved meteoric water, which circulated the wall rocks, was also progressively involved in the magmatic hydrothermal system, and may have dominated the ore fluids during late stage of ore‐forming processes. Therefore, the ore fluid may have resulted from the mixing of calc‐alkaline or alkaline magmatic fluids and evolved meteoric water. All these intrusion‐related gold deposits are believed to be products of Hercynian or Yanshanian calc‐alkaline and alkaline igneous processes along deep‐seated fault zones within the North China craton or along its marginal belts.     

华北克拉通中部造山带早元古代盆地演化

华北克拉通中部造山带被认为是由东、西部陆块碰撞而产生的陆陆碰撞带。然而,关于两个陆块碰撞的时间以及方式还存在着争议。其中一个模式认为俯冲方向是向西的,两个陆块最终碰撞的时间是在2.5Ga左右,而另一个模式则认为俯冲方向是向东的,并且存在着2.1Ga和1.85Ga两期碰撞事件,第三个模式则认为俯冲方向是向东的,而最终的碰撞拼合发生在1.85Ga左右。近几年来,对于中部造山带中浅变质表壳岩系的研究取得了很大进展,为解决以上争议提供了进一步的资料。根据岩石组合和表壳岩中的不整合接触关系,位于中部造山带中段五台杂岩中的滹沱群和吕梁杂岩中的野鸡山群被分成了上下两个部分。其中,两个群的下部以及位于中部造山带南段中条杂岩中的绛县群和下中条群主要由类似于弧后盆地沉积的变质碎屑岩、碳酸盐岩和火山岩组成,而滹沱群和野鸡山群的上部以及上中条群和担山石群的岩石组合则是类似于山前磨拉石建造的变质砾岩和砂岩。来自于这些浅变质碎屑岩中碎屑锆石的年龄为我们提供了源区以及最大沉积年龄的信息。滹沱群和野鸡山群中的碎屑锆石具有两个峰值年龄,2.5Ga和2.15Ga,它们分别对应于中部造山带中段两期重要的岩浆事件。中条杂岩中的碎屑锆石年龄图谱则较为复杂,除了具有2.5Ga和2.15Ga这两个峰值,还具有2.7Ga这个较低和较老的峰值,这些较老的锆石可能来自中部造山带最南端太华杂岩中的古老岩石。弧后盆地沉积中最年轻的碎屑锆石年龄在2.1Ga左右,而山前磨拉石中最年轻的碎屑锆石在1.85Ga左右。结合前人的研究成果,我们给出了一个华北克拉通中部造山带早元古代沉积盆地的演化模式。从2.1Ga左右开始,一系列弧后盆地在"安第斯型"大陆边缘弧之后产生,在之后的东西陆块碰撞过程中他们成为了中部造山带的一部分。从1.85Ga左右开始,东西陆块沿着中部造山带碰撞,导致了陆壳加厚以及随后的快速抬升和剥蚀,从而形成了周缘前陆盆地中的山前磨拉石建造。发生在早元古代晚期的由弧后盆地向周缘前陆盆地的转化支持了华北的最终克拉通化发生在1.85Ga的构造演化模式。     

华北克拉通与全球构造

华北克拉通是中国境内独具特色的大地构造单元,它既不同于新建立的华泰克拉通,又明显有别于扬子地台和塔里木地台。为追溯其形成和演化历史,将全球视为一个整体,在世界范围内寻找与其有宗谱关系的地体。经过认真的对比和鉴别,发现西伯利亚地台、加拿大地盾与中国的华北地台具有特殊的渊源关系。三者合计由14个太古宙原生陆壳块体,于古元古代末(1.79~2.2Ga)通过造山运动碰撞聚合在一起,形成了笔者所称的古劳亚大陆。后者最重要的地质标志就是统一的中元古代盖层,此即中国的长城系、蓟县系,俄罗斯西伯利亚的里菲系和北美洲的层群A、层群B。早寒武世,西伯利亚地台脱离了古劳亚大陆。中寒武世之初即536Ma,古劳亚大陆与形成于1000~1300Ma的Rodinia发生构造拼接,缔造了具有全球规模但命运短暂的超级大陆——Pannotia。这次构造拼接的意义不可低估,在时间上它恰好与骨骼化后生动物的快速发展(“生物大爆炸”)相吻合。过去长时间人们无法理解的,为什么远隔重洋的北美洲-澳大利亚-中国,寒武系中—上统的沉积类型和生物群具有高度一致性的问题,也随之迎刃而解。寒武纪末期510Ma,Pannotia解体并一分为二,在古劳亚大陆与古冈瓦纳大陆之间的地域形成了南太平洋。直到奥陶纪晚期即440Ma前后,古劳亚大陆才分裂,形成了北太平洋,中国北方包括华北和华泰2个克拉通在内,与北美洲的劳伦古陆和内陆地台,才各奔西东。回溯华北地台的渊源,作为一个整体它曾与西伯利亚地台共存了1.3Ga,而与北美的加拿大地盾至少共同度过1.4Ga之久。     

华北克拉通古元古代构造事件

本文讨论了华北克拉通的古元古代表壳岩系、高压麻粒岩和孔兹岩系的若干问题,提出了(1)华北克拉通在约2500Ma太古宙结束时已基本形成.在2300Ma之前处于相对稳定的构造环境;(2)2300～1950Ma期间,华北克拉通经历了一次基底陆块的拉伸-破裂事件,在克拉通内部发育了晋豫、胶辽裂陷盆地和丰镇陆内凹陷盆地;(3)约1900Ma期间,有地幔上涌并伴随辉长岩浆的底侵作用,引起大青山-丰镇地区的超高温变质作用.底侵的辉长岩浆作为岩体和岩墙在下地壳就位,并发生高压麻粒岩相变质作用;(4)约1850Ma期间,华北克拉通经历了一次挤压构造事件,导致了裂陷盆地的闭合和焊接,形成晋豫和胶辽两个类似于现代陆.陆碰撞型的造山带;(5)在华北克拉通的北缘,华北克拉通可能与其北部的另一古老陆块或岛弧拼合,其拼合带应位于白云鄂博以北.现在已残缺不全.孔兹岩系可能代表了平行于北缘造山带的一条构造带.与北部造山带的俯冲碰撞相关的陆内深部逆掩造成了麻粒岩相岩石的形成和抬升;(6)白云鄂博群、化德群和渣尔泰(-狼山)群是与长城系相同时期发育的被动大陆边缘裂谷盆地;(7)1850～1700Ma期间,华北克拉通进入伸展构造体制,导致基底抬升,产生裂陷槽、基性岩墙群和非造山岩浆活动.     

Petroleum Exploration of Craton Basins in China

1 Introduction The craton is a relatively stable continent block which is covered by thick sediments forming significant petroliferous basins and groups of great oil and gas fields. Ivanhoe et al. (early 1990’s) indicated that about half of the 509 large oil and gas fields in the world were related to craton basins (Ivannoe and Leckie, 1993). Mann et al. (2001) suggested that 54.7% of the 592 large fields were developed in the cratonic sag basins and about 30% located in the rifts and depres…     

华北克拉通阜平杂岩的深熔和混合岩化作用

华北克拉通的阜平杂岩长英质岩石中常产出显著的浅色体、岩脉和花岗岩侵入体,并形成广泛的混合岩化作用。通过矿物自形晶的形成、黑云母向角闪石的转换和大量钠长石净边的出现以及其它与熔体活动有关结构的分析,浅色脉体和混合岩化作用的发生与外来熔体的注入有关。在长英质片麻岩中可出现明显的熔体注入,在一些不易片理化的岩石如石英岩中亦可形成浸染状熔体渗入。熔体汇集可形成浅色体、岩脉,直至花岗岩侵入体。而深熔作用本身形成熔体的作用在本区几乎可以忽略不计。在遭受渗透式混合岩化作用的过程中,岩石成分发生了改变,形成开放系统。随着渗透熔体的结晶,可形成一些岩浆锆石,在副片麻岩中则很容易被当作碎屑锆石。     

Structural Relationships along a Neoarchean Arc-Continent Collision Zone, North China Craton

正The Archean North China Craton is composed of the Western Block,Eastern Block and the intervening Central Orogenic Belt.A 4-10 km wide and 85 km long tectonic mélange belt informally called the Zanhuang tectonic     

Eastern Ancient Terrane of the North China Craton

Based on the spatial distribution of ancient rocks and zircons, three ancient terranes older than ca. 2.6 Ga have recently been identified in the North China Craton, namely the Eastern, Southern, and Central Ancient Terranes. The Eastern Ancient Terrane is the best studied and understood of the three ancient terranes. It has a long geological history back to ca. 3.8 Ga ago and includes the areas of Anshan-Benxi, eastern Hebei, eastern Shandong and western Shandong. In Anshan-Benxi, several different types of 3.8 Ga rocks were discovered together with 3.1-3.7 Ga rocks, whereas 2.9-3.0 Ga K-rich granites and 2.5 Ga syenogranite occur on larger scales. In eastern Hebei, 3.0-3.4 Ga rocks and older detrital and xenocrystic zircons were identified. In eastern Shandong, there are a large volumes of 2.7 Ga and 2.9 Ga rocks. In western Shandong, early Neoarchean(2.6-2.7 Ga) intrusive and supracrustal rocks are widely distributed. Whole-rock Nd and zircon Hf isotope data suggest that both mantle additions and crustal recycling played important roles within the Eastern Ancient Terrane during almost every tectono-magmatic event. Most BIFs in the North China Craton are late Neoarchean in age and are distributed on continental crust along the western margin of the Eastern Ancient Terrane, probably suggesting that a stable environment was one of the key factors for the formation of large-scale BIFs.     

华北克拉通的形成演化与成矿作用

华北克拉通具有38亿年的漫长历史,特别是与其他克拉通相比,它有更为复杂的多阶段的构造演化史,记录了几乎所有的地壳早期发展与中生代以来的重大构造事件。在太古宙,华北克拉通经历了>3.0Ga的陆核与微陆块的形成;2.7～2.9Ga的陆壳增生;2.5Ga的岩浆、变质作用与克拉通化;2.3～1.9Ga的古元古代活动(造山)带;1.8Ga的基底隆升与裂谷-非造山岩浆事件。在新元古代—古生代,华北克拉通处于相对稳定的地台状态,其南、北缘受到秦岭造山带和中亚造山带的影响;在中生代,华北克拉通则经历了强烈的中生代构造格局的转变和克拉通的破坏与重建;在新生代,华北克拉通的东缘属于环太平洋构造带的一部分。与上述重大构造事件相对应,华北克拉通出现大规模的成矿作用,形成了丰富多样的固体矿产资源。华北克拉通的形成与演化及其不同类型的成矿系统,为深刻理解大地构造背景对成矿作用的制约提供了范例。     

华北克拉通元古代的三次伸展事件

本文根据作者在山西、河北一带获得的三组元古代年龄数据，即基性岩墙群1.855Ga的Rb-Sr等时线年龄；太古代地层大面积钾质交代的^40Ar-^39Ar坪年龄1．262Ga和^49Ar-^39Ar等时线年龄1．274Ga；以及基性岩墙群0.731-0.601Ga的K－Ar稀释法年龄。结合前人研究资料，作者认为华北克拉通存在1．8－1．7Ga，1.3-1.2Ga，和0.8-0.7Ga三次伸展事件，它们之间相隔0．5GA。最后一次伸展事件可以延续到晚元古代末。文章最后提出了华北克拉通这三次事件与全球超大陆裂解事件是否响应和如何响应的问题。     

华北克拉通中部造山带早前寒武纪变质演化历史评述

根据变质作用程度不同,华北中部造山带早前寒武纪基底可以进一步分为高级区和花岗-绿岩带。前者变质程度可达高角闪岩相-麻粒岩相,包括太华、吕梁、阜平、恒山、怀安、宣化等杂岩,花岗-绿岩带的变质程度较低,多为绿片岩相-角闪岩相,包括登封、赞皇、五台等杂岩。已有变质演化研究表明,高级区恒山、怀安和宣化杂岩中的麻粒岩和(或)退变榴辉岩记录的峰期变质压力最高,恒山杂岩、阜平杂岩和宣化杂岩中的麻粒岩记录的峰期变质温度最高;花岗-绿岩带中的赞皇杂岩和五台杂岩出露高压斜长角闪岩和高压变泥质岩。中部带各变质杂岩中可识别出早期进变质、峰期、峰后快速降压和晚期冷却等变质阶段,拥有顺时针近等温降压型的变质作用P-T轨迹,与华北克拉通中部的俯冲碰撞有关。大量变质年代学数据显示,中部带各变质杂岩中至少记录了~1.85Ga、~1.95Ga和~2.5Ga三组变质年龄,其中,~1.85Ga的变质年龄占据了主导地位,大致与区域片麻理形成的时间一致,代表变质高峰期时代;~1.95Ga的变质年龄代表了峰期前的某个进变质片段;~2.5Ga的变质年龄则指示了更早一期的变质事件,推测与古老陆块~2.5Ga所遭受的大量幔源岩浆的侵入和底垫作用有关。然而,变质年龄与变质阶段的对应关系尚不明确。     

华北和圣弗朗西斯科克拉通前寒武纪地质对比

一些学者提出华北克拉通在新元古代早期之前与圣弗朗西斯科克拉通（圣弗朗西斯科-刚果克拉通）相邻,但缺少证据;本文总结两个古陆地质记录,为评价这一古构造格局模型提供线索。两个古陆陆壳生长的峰期均为～2.7 Ga前;不同之处是,华北古陆经历了显著的～2.5 Ga前的陆壳生长和改造,而圣弗朗西斯科克拉通则似乎没有。华北古陆2.4～2.2 Ga期间发育少量变质火山-沉积岩系和花岗岩,～2.1 Ga前后广泛发育裂谷火山-沉积建造及侵入岩,2.0～1.9 Ga发育超高温变质作用和类似弧岩浆活动,导致两个克拉通（东、西华北克拉通）拼合形成统一的华北古陆;同一时期,圣弗朗西斯科克拉通南、北缘发育2.4～2.0 Ga岩浆作用,指示长期处于大陆边缘弧或者岛弧背景,～2.0 Ga还发育超高温变质作用。两个古陆都发育～2.0 Ga前类似大陆边缘弧特点的岩浆活动,只是圣弗朗西斯科克拉通时代稍早。1.8 Ga以来,两个古陆均发育多期岩墙群,部分基本同期,如～1.78 Ga岩墙群、～1.7 Ga岩墙群和～0.92 Ga岩墙群等;不同的是,华北古陆发育约1.3～1.2 Ga岩床/墙群,而圣弗朗西斯克拉通发育～1.5 Ga岩墙群。1.8～0.8 Ga,两个古陆上都断续发育（火山）-沉积建造：1.8～1.6 Ga以及1.4～1.2 Ga,两者的沉积建造同样以石英砂岩等碎屑岩为主,碳酸盐岩较少;1.2～1.0 Ga前,两者的记录均较少,或暂不能确定;1.0～0.8 Ga,两者均发育碎屑岩和碳酸盐岩;1.6～1.4 Ga,华北古陆发育碳酸盐岩建造,而圣弗朗西斯科克拉通则发育碎屑岩建造。华北古陆新元古界地层中碎屑锆石常显示～1.5 Ga的峰值,该期岩浆岩鲜少报道于华北古陆,但却见于圣弗朗西斯科克拉通。两个陆块都发育太古宙-古元古代条带状铁建造铁矿、古元古代石墨矿、中新元古代沉积-喷流型铅锌矿等。不过,华北古陆发育的古元古代硼矿、菱镁矿,中元古代碳酸岩型稀土矿等在圣弗朗西斯科不发育;而后者发育的绿岩带型相关金矿、镍矿、祖母绿宝石矿等,华北似乎不发育。另外,0.7～0.5 Ga,圣弗朗西斯科克拉通周边广泛发育泛非期造山带,而华北古陆并没有这一事件的明确记录;显生宙,圣弗朗西斯科克拉通相对稳定,中生代与刚果克拉通分离;但华北古陆内部经历强烈的构造-岩浆活动（峰期在中生代）。华北与圣弗朗西斯科克拉通前寒武纪是否相邻还需进一步地质对比和古地磁工作,尤其应关注约2.0～1.9 Ga岩浆-变质（造山）事件、约1.8～1.7 Ga岩浆-沉积（裂谷）事件以及约0.9 Ga岩浆-沉积（裂谷）事件。从地质记录的相似性角度来看,华北东南缘与圣弗朗西斯科南缘的地质记录相似性最大,可延续性最强,最可能相邻。     

Paleomagnetic Evidence for Tectonic Setting of Paleoproterozoic Dyke Swarms in the North China Craton,China

正In order to investigate the tectonic setting of 1.77-1.78Ga dyke swarms emplaced into the central North China Craton(NCC),we carried out a paleomagnetic and magnetic fabric study on the well geochronologically     

冀东地区始太古代早期—冥古宙锆石发现

内容提要:最古老大陆地壳的形成、组成和演化是阐释地球壳幔物质分异、构造演化的逻辑起点.由于长期地质作用改造,地球上保存的古老陆壳物质十分稀少,寻找和研究都极具挑战性.在冀东卢龙喇叭山地区,早期研究发现含有大量3.4～3.8 Ga碎屑锆石的铬云母石英岩,岩石特征和碎屑锆石年龄分布与迁安黄柏峪地区的铬云母石英岩十分类似.本...     

Geochemistry Characteristics of the Diaoyutai Complexes in Liaoning, eastern North China Craton

<正>1 Introduction There are complex rocks exposed in the Diaoyutai area which is in western Liaoning,eastern North China Craton.The Neo-Archean"Suizhong migmatitic granites"are the important parts of the Diaoyutai     

河北承德大庙铁矿床地质构造特征与找矿预测

大庙斜长岩杂岩体位于华北克拉通北缘,是我国唯一岩体型斜长岩杂岩体,赋存了丰富的Fe-Ti-P矿床.对该杂岩体的岩石学、矿床成因研究已经较为深入,但是矿田构造研究较为薄弱.本文主要从大庙矿床地质特征分析入手,通过控矿构造分析和成矿期构造应力场的恢复,结合成矿特征分析,建立大庙矿床找矿预测模型,开展找矿预测.在大庙杂岩体内,先后找到了大庙、黑山、马营和罗锅子沟等中—大型矿床,它们都具有典型的岩浆矿床特征,具有岩浆熔离、分异和贯入式成矿特征;系统的野外地质调查和翔实的构造解析表明,大庙杂岩体的侵位受控于EW向隆化-平泉和大庙-红石砬子的断裂构造,杂岩体内NE和NW向两组断裂构造控制了杂岩体内铁-铁磷矿带的发育,NS向断裂则主要为成矿后构造,往往错断了铁矿体.在黑山矿区,野外观测发现含矿苏长岩利用了固结斜长岩中发育的节理,呈脉状贯入,在节理交汇部位铁矿体变大变富;通过节理和矿脉走向的详细测量和吴氏网统计分析,推测大庙矿区成矿期含矿苏长岩的侵位受控于区域上近似NS向的挤压应力作用.根据大庙杂岩体的岩浆侵位时代、岩相-矿体的接触关系、控矿构造和成矿特征,复原了大庙杂岩体的成矿-构造演化过程:最早期区域构造活动控制了斜长岩的侵位,没有发生矿化;苏长岩的侵位,伴随发生了早期的结晶分凝式矿化;块状苏长岩的侵位导致了晚期的熔离-贯入式矿化的形成;成矿期后,大庙杂岩体还经历了多期次的构造变动、抬升和剥蚀.在此基础上,建立了大庙铁矿床的找矿预测模型,并系统分析了大庙矿田不同矿区的深部和外围的找矿潜力,认为黑山和大庙矿区的深部、黑山矿区东侧和北侧、大庙杂岩体的东部边缘可能被中生界覆盖的区域等地段都具有很好的找矿空间,大庙矿区铁矿资源潜力巨大.