中国东南部中生代受古太平洋板块俯冲的影响,火山作用强烈,在东南沿海地区形成巨型火山-侵入杂岩带.根据火山岩组合特征、火山岩时空分布规律、区域不整合、构造背景及其成矿作用类型,分为4个旋回:第Ⅰ旋回(200～165 Ma),为一套近EW向的拉斑玄武岩-流纹质火山岩构成的双峰式火山岩,其中的玄武岩主要起源于软流圈地幔,形成于印支造山后板内伸展环境,该时期成矿作用较微弱.第Ⅱ旋回(165～145 Ma),处于陆缘弧由俯冲挤压高峰期向挤压后的伸展过渡时期,零星分布钙碱性系列英安质-安山质岩石组合,伴生浅成低温热液型金矿和叶腊石等非金属矿产.第Ⅲ旋回((145～115 Ma),华南进入古太平洋板块俯冲挤压后的伸展阶段,发生遍及全区的强烈火山活动,形成诸多大型火山机构和大面积高钾钙碱性系列流纹质-安山质火山岩组合,是中生代活动最强、影响范围最大的一期火山活动,伴生有丰富的金属、非金属、稀土矿产,矿床类型以浅成低温热液型为主.第Ⅳ旋回(115～85 Ma),火山活动相对微弱,并向东迁移至沿海地区,与A型花岗岩带共生,为一套后造山环境下的双峰式火山岩、过碱性流纹岩,晚期往往伴随大规模碎斑熔岩侵出,此阶段形成丰富的金属和明矾石、叶腊石等非金属矿产,以浅成低温热液型为主,斑岩型次之.

Magma mingling (mixing) is one of the main mechanism for the diversity of igneous rock, as well, it is a very important trigger to volcanic eruption. Previous studies have been focused on the magma mixing between mafic and silicic magmas. However, in recent years, more and more petrologists realized that the mingling between silicic magmas could be more common and important. In this paper, we study the phenomenon of magma mingling between trachytic and rhyolitic magmas in a small crater of the Xiaoxiong Caldera, eastern Zhejiang Province. On the outcrops, trachytic lumps scatter in the rhyolite, showing various sizes and with band, lense or balloon shapes. The phenocrysts of trachyte are composed of orthoclase + titanomagnetite + apatite + zircon and often aggregated to a glomerocryst. We can find the reaction texture in the titanomagnetite + apatite + zircon aggregate, which are surrounded by biotites. It is noted that the orthoclase phenocrysts are generally large and heavily resorbed. In contrast, phenocrysts in rhyolite are mainly orthoclase and quartz, they are usually small and the resorptions of feldspar are rare. Major and trace elements characters as well as other geological evidences show that both silicic magmas are originated from a common crust source, and have experienced mechanically mingling. Their geochemical variations are mainly controlled by fractional crystallization. The differences of whole-rock compositions, mineral compositions, and structures between trachytic and rhyolitic magmas indicate that both magmas should be derived from different parts of one chamber. The trachytic magma could represent the crystal mush (orthoclase + titanomagnetite + zircon + apatite) in bottom or wall of the chamber, while the more evolved rhyolitic magma could be stored at the upper part of the chamber, where is rich in melt and poor in crystals. We believe that the mingling between two silicic magmas is the result of self-mingling in a shallow magma chamber. This process may be controlled by the ponding of the mafic magma at the bottom of the silicic magma chamber. That is, when hot mafic magma ponds at the base of magma chamber, the trachytic magma in the bottom of the chamber is rapidly heated up and rejuvenated, and then it moves up and mingles with the upper rhyolitic magma. This study may provide an important reference for understanding the large-scale silicic volcanic eruptions, magma evolution and magma chamber structures in the southeastern coastal area of China, as well give a reliable case of magma self-mingling effect in shallow magma chamber.

中国造山带面积约占全国陆域面积的3/5.造山带区由于经历过复杂的多岛洋演化,陆缘增生与陆-陆碰撞等多期次强烈的构造活动,形成了类型多样的混杂岩.混杂岩的识别与分类是造山带地质编图的重点与难点.本文介绍国际国内对混杂岩概念的理解,对与混杂岩紧密相关的名词术语,如蛇绿岩和蛇绿混杂岩、俯冲增生杂岩、杂岩、岩片和超岩片、非史密斯地层、构造地层、洋板块地层、对接缝合带、叠接缝合带等的含义进行了阐述.针对中国造山带地质特征,中国造山带混杂岩可划分出沉积混杂、构造混杂、沉积-构造复合混杂三大类.沉积混杂主要发生在威尔逊旋回的早期阶段(洋拉张阶段),构造混杂和沉积-构造复合混杂主要发生在威尔逊旋回的晚期阶段(洋俯冲消减-碰撞阶段),俯冲增生杂岩是俯冲带由俯冲消减-碰撞作用形成的构造混杂岩.

系统梳理西太平洋南段(包括华南、日本、菲律宾及东印度尼西亚)部分地区的新生代构造-地层特征,并以区域性角度不整合为主要依据,对喜马拉雅运动期次、时代及其构造背景进行探讨.研究区受白垩纪末期晚燕山运动的影响,古新统乃至下始新统大都缺失,新生界高角度不整合于前新生界之上.根据不同构造单元内地层沉积-火山类型及接触关系对比,研究区新生界可分为3个构造层,即始新统—渐新统、中新统或上渐新统—中新统及上新统以上.上述3个构造层之间为2个穿时的区域性角度不整合分隔,分别对应早喜马拉雅造山运动(33～20 Ma)及晚喜马拉雅造山运动(5.3～2.6 Ma)界面,并以前者最强烈.区域2次构造运动均与岛弧或裂离微地块向欧亚板块边缘的碰撞拼贴有关,指示西太平洋南段喜马拉雅运动是发生于大陆边缘的增生造山过程,受控于太平洋板块和印度洋-澳大利亚板块运动方向与速率变化.在2次构造事件期间,始新世和中新世弧后的强烈伸展,导致华南大陆边缘古老山系的夷平及边缘海的产生,并最终形成现今的地质及地理格局.

通过对浙东小雄破火山晚白垩世火山岩(流纹岩)-浅成侵入岩(正长斑岩)进行系统的岩相学和地球化学分析,探讨了火山-侵入杂岩的成因及岩浆演化过程.研究表明,小雄破火山晚白垩世流纹岩和正长斑岩经历了不同的结晶分异过程:流纹岩经历了碱性长石+磷灰石+锆石的分异;正长斑岩经历了普通辉石+磷灰石+ Ti-Fe氧化物的分异.流纹岩和正长斑岩的母岩浆均起源于地壳物质的重熔,但各自有相对独立的演化过程,两者非同一岩浆房内某一岩浆连续分异的产物.推测在小雄破火山之下不同深度存在由多个子岩浆房构成的复杂岩浆系统,暗示东南沿海晚中生代火山-侵入杂岩中的侵入岩并不完全代表岩浆房下部的堆晶部分.

Hong Kong is located at the southern margin of a Mesozoic igneous belt in Southeast China, where voluminous magmatism formed during the Early Jurassic to Early Cretaceous. The final phase of volcanism formed the rhyolitic High Island Formation, which shows geochemistry similar to A‐type granite. For example, these rocks have high content of SiO 2 and alkali (e.g., high K 2 O + Na 2 O, with K 2 O/Na 2 O ratios greater than 1.0) and are characterized by weakly enrichment in high‐field‐strength elements (HFSEs) and rare‐earth elements (REEs) (except for Eu) and extreme depletion of Ba, Sr, P, Ti, and Eu, with high 10,000× Ga/Al ratios. Zircon U–Pb dating for three porphyroclastic rhyolite samples from the High Island Formation yielded weighted mean 206 Pb/ 238 U ages of 140.0 ± 0.8, 139.8 ± 0.7, and 139.1 ± 1.1 Ma. These zircons have ε Hf ( t ) values of −9.0 to +0.4, with two‐stage Hf model ages ( T DM2 ) of 1,763–1,172 Ma, indicating a magma source that involved melting of predominantly Palaeoproterozoic to Mesoproterozoic continental crust with a minor juvenile mantle component. The ~140 Ma A‐type magmas in Hong Kong area were probably formed in response to rollback and/or break‐off of the Palaeo‐Pacific Plate. Previous studies indicate that the tectonic transformation from the Palaeo‐Tethys to Palaeo‐Pacific tectonic domain occurred at >165 Ma. Hong Kong underwent a repeated slab subduction and rollback process involving (a) Palaeo‐Pacific Plate subduction formed I‐type granites and continental margin arc volcanic rocks at 165–161 Ma; (b) slab rollback lead to the formation of A‐type granites at 161–159 Ma with minor magmatism formation during the rollback stage at ~159–148 Ma; (c) renewed slab subduction formed continental margin arc rocks at 148–141 Ma; and (d) renewed slab rollback resulted in the formation of A‐type volcanic rocks at 141–139 Ma (e.g., High Island Formation).

余姚—丽水断裂带是浙东南地区活动时间长、延伸远、发育比较宽的一条NE—NNE展布的断裂构造带,在浙江嵊州地区上火山岩系磨石山群和下火山岩系永康群中构造形迹表现十分明显.余姚—丽水断裂带由一系列NE—NNE向控制区内白垩纪盆地形成与发展的正断层,以及NE—NNE走向、自北西向南东逆冲的叠瓦状断层和轴迹呈NE—NNE向的褶皱组成.通过对其构造活动特征及控制新老地层的时序关系研究,结合区域构造活动规律和时空演化关系等综合分析认为:正断层形成时间较早,控制白垩纪盆地的形成和发展,与早白垩世岩石圈伸展减薄形成的拉张作用密切相关;叠瓦状逆冲断层及斜歪褶皱、紧闭同斜褶皱等褶、断构造组合形成于晚白垩世之后,其动力学机制可能与古太平洋构造域向太平洋构造域的转换效应有关.研究成果为深入探讨浙东地区燕山期构造演化提供了新的素材和资料.

The"volcanic structure-volcanic lithofacies-volcanic lithology"trinity mapping method has been wildly used in the con?tinental volcanic rock outcrop area of China since the 1990s. This paper discussed the applicability of this mapping method in the 1:50000 Shengzhou geological mapping program for large outcrop area of Cenozoic basalts. According to field investigation and re?search work in the Cenozoic basalt area, the remote sensing technology and the new remote sensing images are the key factors of the volcanic rock area mapping. Image interpretation combined with field verification is one of the effective methods to improve the quality and effectiveness of the mapping. In the field, the special landscape and outcrops of eruption facies of breccias and volcanic neck facies of basalt porphyrite often indicate the central position of the volcano. Volcanic rock facies and eruption gaps are the key factors for the division of volcanic cycle. Volcanic edifice, volcanic lithofacies, volcanic lithology-space-time change are the key fac?tors for restoration of ancient volcanic eruption histories.

Borehole ZK10 is located in Xinghua City, Jiangsu Province. Based on litho-, bio-, magneto- and chronostratigraphic study of the core sediments, the authors established its Quaternary chronological framework:①The lower boundary of Quaternary, con?sistent with the G/M boundary at 2.58Ma, was found at 212m in depth. The Lower Pleistocene in this core was composed of the lower, middle members and lower to mid-parts of the upper member of the Wuduizhen Formation, and corresponded to the pollen zonesⅠ-1 andⅠ-2.②The Early/Middle Pleistocene boundary, in accord with the M/B boundary at 0.78Ma, was found at 120m. This was defined at the boundary between the pollen zonesⅠ-1 andⅡ. The Middle Pleistocene was composed of the top part of upper member of Wuduizhen Formation and the lower member and the lower-to mid-parts of the upper member of the Xiaoyaozhuang Formation. The Wuduizhen Formation was a time-transgressive lithostratigraphical unit across the Lower/Middle Pleistocene.③The Middle/Late Pleistocene boundary at 120ka BP was found at the depth of 81.5m. It lay on the boundary between the pollen zonesⅡandⅢ-1, and essentially coincided with the boundary between Xiaoyaozhuang Formation and Guannan Formation. The latter was another time-transgressive unit crossing both the Middle and Upper Pleistocene. The Upper Pleistocene was composed of the pollen zones Ⅲ-1,Ⅲ-2,ⅣandⅤ.④The Late Pleistocene/Holocene boundary, about 10ka BP, 12.25m, lay on the pollen boundary between zonesⅤandⅥ. Lithostratigraphically, Holocene deposits belong to the Yujian Formation and correspond to the pollen zoneⅥ.

A 74m core was obtained from Borehole CSJA3, drilled in Qindong Town, Yancheng City of Jiangsu Province. Multi?stratigraphic studies, which included sedimento-, chrono-and biostratigraphy, were carried out for its core sediments. Consequently, three foraminifera assemblages since the Late Quaternary were preliminarily distinguished, which corresponded to‘Zhenjiang Trans?gression’,‘Gehu Transgression’and‘Taihu Transgression’, respectively. This correlation confirmed that such three transgressions all occupied the borehole area and the transgressive records were well preserved. Moreover, seven palynological assemblages, revealing variability of the climate and sedimentary environments in the same period, were composed of the following assemblages:(P 8) Cyper?us-Graminea assemblage, 0~7.8m, warm and humid, salt marsh to supratidal upwards;(P7) Pinus-Chenopodiaceae-Artemisia assem?blage, 7.8~11.0m, cold and dry, fluvial flood plain; (P6) Pinus-Quercus-Gramineae-Chenopodiaceae-Compositae assemblage, 11.0~30.0m, moderate warm and slightly dry, fluvial flood plain upward to intertidal; (P5) Ring algae-Artemisia assemblage, 30.0~37.2m, cold and dry, fluvial flood plain;(P4) Pinus-Compositae assemblage, 37.2~43.55m, warm-cool to cold-dry, intertidal to sub?tidal; (P3) Quercus-Pinus-Gramineae assemblage, 43.55~50.0m, warm and humid, intertidal; (P2) Pinus-Quercus-Compositae-Concentricystes aseemblage, 50.0~65.0m, warm-cool to dry, bank-attached bar and fluvial-flood land facies.

中国东南大陆晚侏罗世地层普遍缺失,仅零星见于个别地区,香港新界东北的荔枝庄组即为其一.荔枝庄组出露于香港世界地质公园沉积岩园区的荔枝庄地区,自下往上由火山岩—沉积岩—火山岩组合而成,沉积岩中发育大型包卷层理和滑塌构造等典型沉积构造,是香港地区最具代表性的晚侏罗世火山—沉积岩系.通过实测地层剖面研究,确定其成岩过程大体上可划分为早期普林尼式火山爆发、中期破火山口湖相沉积和晚期普林尼式火山爆发三个阶段,以湖相沉积作用为主、火山喷发作用为辅;受晚期火山岩浆活动的影响,沉积岩层普遍发生硅化或炭化.荔枝庄组独特的岩石组合与形成的古地理环境,为探讨中国东南大陆中生代火山活动—沉积作用方式与成岩过程,提供了难得的研究实例.

By studying on the chronology,mineralogy and metamorphism of Caledonian garnet amphib-olite first discovered in the Qinzhou-Hangzhou joint belt,it is concluded that the garnet amphibolite, which possesses typical clockwise P-T-t path including amphibolite-facies prograde metamorphism in early stage,eclogite-facies(UHP)peak metamorphism in middle stage and amphibolite-facies retrogressive met-amorphism in late stage,yields a metamorphic age of 454±4 Ma.The mineral assemblage of the amphibo-lite-facies prograde metamorphism in early stage is amphibole(Amp)+plagioclase(Pl)+quartz(Qtz)with temperature of 71 9℃~795℃ and pressure of 7.56Kpa~8.30Kpa,the eclogite-facies(UHP)peak meta-morphism in middle stage has the mineral assemblage of garnet(Gt)+ akmite (retrograde to diopside+al-bite)±Qtz with temperature of 668℃~821℃ and pressure of 26.42 Kpa~33.46 Kpa,the amphibolite-fa-cies retrogressive metamorphism in late stage is composed of Gt + Amp + Pl ± Qtz with temperature of 61 1℃~854℃ and pressure of 4.76 Kpa~9.30 Kpa.Combined with the previous studies,it is proposed that the Qinzhou-Hangzhou joint belt had undergone evolutionary process of eclogite-facies(UHP)meta-morphism,granulite-facies retrogressive metamorphism and amphibolite-facies retrogressive metamor-phism in Caledonian.The first discovery of the Caledonian UHP metamorphism in the Qinzhou-Hangzhou joint belt indicates that the collision between Cathaysia and Yangtzs blocks occurred in Caledonian.

溧水火山岩盆地是长江中下游地区众多中生代火山岩盆地之一，在盆地内自下而上发育有龙王山组、大王山组、姚家边组和甲山组粗面质火山岩和若干个同源的次火山侵入岩体。针对溧水盆地火山岩一次火山岩进行系统的锆石U—Pb年代学研究，结果显示，龙王山组玄武质粗面岩的锆石U—Pb年龄为135Ma±1Ma，大王山组粗安岩的锆石U—Pb年龄为131Ma±1Ma，姚家边组粗安岩的锆石U—Pb年龄为128Ma±1Ma，另外1个粗安斑岩体的年龄为131Ma±1Ma，它们均为早白垩纪岩浆活动的产物。上述年龄数据与长江中下游地区其他盆地火山岩的年龄基本一致，表明长江中下游地区中生代火山岩的喷发时代主要集中在135Ma～127Ma之间，均受制于中国东部岩石圈减薄的伸展构造背景。

在香港世界地质公园西贡火山岩园区的万宜水庳周边、粮船湾海诸岛屿、清水湾半岛东南部等地,连续出露粮船湾组火山岩,因其优美的火山岩石柱景观（柱状节理）而成为公园的核心景区,尤其是万宜水库东坝一带的火山岩石柱景观,曾被评为"香港十景"之首,六边形石忭也被选为香港国家地质公园的徽

The columnar joints of High Island Formation are the largest rhyolitic porphyroclastic lava columns in the Sai Kung volcanic rock regions ,Hong Kong global geopark .On the basis of field investiga-tion and measurement ,the authors pursue the structural features and origin of these primitive columnar joints .It shows that not all the porphyroclastic lavas of High Island Formation occurred columnar joints , the columnar joints can be divided into three types ,i .e .,well-developed ,sub-developed (destructed by secondary joints) and undeveloped .The sections of the volcanic columns are mainly hexagonal in shape , and partly pentagon and irregular .T heir diameters are 1~3 meters and the heights are generally 20~30 meters ,most of them dip steeply towards the NW-trending and SW-trending .Occurring measurements of primitive columnar joints show they have various directions in cylinder ,which conforms to the contraction-condensation model ,and secondary joints and marine abrasion destroyed morphologies of columnar joints .

Cretaceous volcanic rocks outcrop expensively in the adjacent area of Zhejiang-Fujian provinces and can be subdivided into the Lower Upper Volcanic Series.The earlier Lower Volcanic Series are widelyspread felsic volcanic rocks formed at early stage of Early Cretaceous.They belong to weakly peraluminous high-K calc-alkaline series,are enriched in LILE(such as Cs、Rb、Ba、Th、K、Pb)and LREE without evident Eu anomalies,depleted in HFSE(such as Nb、Ta、Ti、P),show loweHf(t)values(-20.43~-6.39)and old crustal model ages(TDM2mostly between 1.8and 2.2Ga).The later Upper Volcanic Series are felsic volcanic rocks which formed at late stage of Early Cretaceous and expose only in faulted basins.They belong to metaluminous high-K calc-alkaline series,contain similar LILE and LREE to the Lower ones,but have evident Eu anomalies,lower SiO2 total alkaline contents and highereHf(t)(-10.00~-4.51).Both the Lower and Upper Volcanic Series show decreasingΣREE and differentiation degrees of LREE with time,they are mostly high-Sr rhyolitic rocks formed in active continental margin setting,and derived from partial melting of Proterozoic basements caused by underplating of mantle magmas.However,the Upper Volcanic Series underwent more crust-and mantle-derived magmatic mixings.Different from above rocks,the lava at the top of Xishantou Formation is Shoshonite series highSr trachyandesite.It is a kind of very rare rock in coastal Southeast China,enriched in Sr,Ti,Co,Ni but lowereHf(t)values,and is inferred to result probably from fractional crystallization of mantle-derived basic magma.Based on comprehensive comparisons of Late Mesozoic volcanic rocks,it is summarized that the crust-mantle interactions in Southeast Coast of China incerased temporally from Middle-Late Jurassic to late stage of Early Cretaceous,and weakened spatially from south to north.

According to the postglacial sporo-pollen distribution from the typical borehole CSJA6 in the paleo-incised valley of the Yangtze River Delta, combining with the forams analysis and AMS 14C dating of 6 samples, 3 sporo-pollen assemblages with time calibration from below were established: I. Quercus-Lipuidambar-Artemisia-Polypodiacea assemblage, belonging to the early Holocene; II. Quercus-Castanopsis-Cyperaceae-Pteris assemblage, belonging to the early-middle Holocene; III. Quercus-Ulmus-Artemisia-Polypodiacea assemblage, belonging to the middle-late Holocene. These three sporo pollen assemblages reflect the paleoclimate evolution process as cold and dry-hot and wet-warm and dry, which is consistent with the climate environment of China. This research is basically identical with the results of previous studies in this region.