西准噶尔构造带包古图地层小区上泥盆统红山梁组的建立及地质意义

西准噶尔构造带包古图地层小区白碱滩北红山梁剖面上新发现一套晚泥盆世红色“硅质岩、粉砂质硅质岩、凝灰质硅质岩”海相沉积组合,与上覆包古图组深灰色—灰黑色含碳粉砂岩呈整合接触。经区域对比确认,该套地层显著有别于研究区乃至整个西准噶尔构造带地层分区已发现的全部上泥盆统各组岩石地层,符合“野外可识别、界面可区别、区域可对比、图面可表达”的原则,据此新建红山梁组。本次于红山梁组枕状玄武岩、玄武岩、安山岩中分别获得365.9±5.0Ma、370.6±7.4Ma和374.6±3.6Ma的LA-ICP-MS锆石U-Pb年龄,佐证其时代为晚泥盆世。红山梁组与包古图组连续沉积之确认,消除了包古图组老于希贝库拉斯组这一存疑,建立了完整的下石统地层序列,新增了包古图地层小区泥盆纪的沉积记录,为区域沉积与构造演化研究提供了新资料。

塔里木盆地西北缘埃迪卡拉纪—寒武纪转折期黑色岩系中硅质岩成因及其环境指示意义

埃迪卡拉纪—寒武纪转折期是地质历史上的关键期,全球范围内普遍发育一套黑色岩系,包括硅质岩、泥岩和白云岩。在这套黑色岩系中下部,发育了不同厚度的硅质岩,尤其是在塔里木盆地西北缘,黑白燧石条带韵律性互层且硅质岩分布变化大,其成因对寒武系玉尔吐斯组优质烃源岩形成环境具有重要指示意义。本文以塔西北地区新柯地1井这套黑色岩系中硅质岩为研究对象,运用岩芯观察、镜下薄片鉴定、主微量元素和稀土元素分析,研究硅质岩与有机质的成因及其二者之间的共生机理,硅质岩较高的Ti、V、Y、Ba等元素含量、较低的δ^(30)Si值(1.2‰~0.7‰)、明显的Ce负异常说明其硅质流体为热液来源,但是硅质岩不是热液脉体侵入形成,而是富含硅质的流体与冰冷的海水混合沉积而成,硅质岩沉积受温度、pH值、有机质等因素共同控制,有机质的存在可以促进硅质沉淀。同时系统地研究了黑白燧石条带韵律性互层的成因,白色层由纯的微晶石英组成,而黑色层由碎屑碳质颗粒、石英颗粒和碳质纹层组成,认为是微生物席活动的结果,硅质岩中黑白燧石层受冰期和间冰期控制。硅质岩中较高的Al_(2)O_(3)/(Al_(2)O_(3)+Fe_(2)O_(3))比值和较低的Lan/Cen比值代表受陆源影响的大陆边缘沉积环境,结合古气候、海平面变化等信息,认为塔西北地区寒武系玉尔吐斯组硅质岩以及硅质页岩沉积于局限海湾或潟湖环境,为正确认识硅质页岩的形成环境和烃源岩的评价预测提供理论指导。

下扬子中二叠统孤峰组热液硅质岩地球化学约束及其意义

【目的】下扬子地区中二叠世沉积了一套富含有机质的孤峰组黑色硅质岩,热液硅质岩的分析是该区硅质岩与异常高有机质富集关系研究的关键,进而为该区页岩气勘探提供理论依据。【方法】利用主量、微量和稀土元素地球化学结合岩相学特征分析,安徽铜陵叶山和巢湖平顶山地区孤峰组硅质岩的成因及其构造背景。【结果】巢湖地区孤峰组黑色薄层硅质岩中富含硅质海绵骨针以及放射虫,而铜陵地区孤峰组青灰色硅质岩中几乎不含硅质生物,由微晶石英组成。热液活动指标Al/(Al+Fe+Mn)、Eu/Eu^(*)、Al-Fe-Mn三角图、Lu_(N)/La_(N)比值指示铜陵地区孤峰组青灰色硅质岩为热液成因,巢湖地区孤峰组黑色薄层硅质岩为生物成因。微量和稀土元素La-Th-Sc三角图以及La/Sc与Ti/Zr交会图指示铜陵地区孤峰组沉积期为洋岛弧构造背景,而巢湖地区为陆岛弧和主动大陆边缘背景。【结论】铜陵地区孤峰组硅质岩为原生热液硅质沉积,是斜坡带活跃的构造裂陷活动带来的热液硅酸沉积而成。下扬子地区孤峰组黑色层状硅质岩虽然为生物成因,但其硅的来源与斜坡带的热液活动有关。下扬子地区孤峰组富有机质沉积可能与热液活动带来大量的营养物质造成浮游生物的繁盛有关。

Formation Mechanisms of Some Features in Siliceous Upper Cretaceous-Lower Tertiary Beds of Jordan-Undulations, Geodes, Boudinages

Geode, boudinage, and undulation structures are widely distributed in the siliceous beds of the Upper Cretaceous/Tertiary rocks in Jordan. Their formation was attributed to tectonic forces, syngenetic processes, organic disintegration processes, subaquatic gliding, compaction and settlement, and meteoritic impacts. In this work, the structural features in the siliceous beds of Jordan are attributed to an interplay of load and directed pressures, and mineralogical transformation processes (opal-A to opal-CT to quartz), governed by pH changes. Tectonic directed pressure was acting in an ESE-WSW direction and is common in the silicified limestone of Upper Cretaceous.

塔里木盆地西北缘早寒武世玉尔吐斯组硅质岩成因

对塔里木盆地西北缘下寒武统玉尔吐斯组硅质岩开展岩石学以及元素与硅同位素地球化学研究,探讨硅质岩的成因及沉积模式。岩石学观察表明,玉尔吐斯组中段硅质岩主要由隐晶硅质和微晶石英组成,未见碎屑石英,排除了陆源输入对硅质岩沉积的影响。玉尔吐斯组下段硅质岩相对富Fe且具有显著的Eu正异常,反映了硅质岩可能主要来源于海底热液;而中段硅质岩显示Y/Ho比值较高、中等Ce负异常、LREE亏损和Y正异常,说明硅质来源主要为海水,这也符合中段硅质岩具有总体偏向热水来源的δ^(30)Si值。此外,氧化还原敏感元素指标表明,玉尔吐斯组硅质岩的沉积环境为表层海水氧化,而底层海水缺氧甚至硫化。研究认为,玉尔吐斯组硅质岩的沉积模式为:下段硅质岩由大量富硅热液在上升流作用下直接沉积,之后热液活动减弱,氧化还原分层海洋促进海水中溶解的硅和铁循环耦合,硅质以Fe^(3+)-Si胶体形式共沉积,当硫化水域盛行时铁和硅循环解耦,沉积黑色页岩,形成中段硅质岩和黑色页岩互层。

马来西亚沙巴州Chert-Spilite组砂岩碎屑锆石U-Pb年龄及其地质意义

马来西亚沙巴州出露大面积的蛇绿岩套,其中以KET蛇绿岩和Chert-Spilite (Cs)组硅质岩和碎屑岩为代表。笔者以沙巴州Cs组中的砂岩为研究对象,对碎屑锆石U-Pb年龄进行分析,其结果显示样品KDS-Cs-1碎屑锆石年龄具有190~68 Ma (22%)、279~213 Ma (18%)、627~315 Ma(22%)和2 788~976 Ma (37%)四个区段分布特征,主峰值分别为117 Ma、234 Ma、415 Ma和1877 Ma。样品BLR-Cs-1碎屑锆石年龄具有196~90 Ma (20%)、350~212 Ma (19%)、770~404Ma (12%)和3 423~873 Ma (48%)四个分区特征,主峰值分别为104 Ma、249 Ma、509 Ma和1848 Ma。Cs组砂岩碎屑锆石年龄图谱表明前寒武纪锆石居多,其中还发现了一颗古太古代(3 423Ma)的锆石。通过对比与分析沙巴周边块体构造演化、地质特征和碎屑锆石年龄图谱,推测沙巴Cs组砂岩物源区主要为华夏-南海北部陆块、南沙地块和印支地块。

Geochronology and Geochemistry of the Radiolarian Cherts of the Mada'er Area,Southwestern Tianshan:Implications for Depositional Environment

In the southwestern Tianshan,the geologic ages of many strata and their depositional environments are still poorly constrained because of complex structures.The Mada＇er area is located in the Kuokesaleling belt,Southwestern Tianshan.The cherts from the former Wupata＇erkan Group contain abundant radiolarian fossils,including 10 species which are identified as late Devonian to early Carboniferous in age.Eleven chert samples have SiO_2 contents ranging from 88.80 wt%to 93.28 wt%, and 2.02 wt%to 3.72 wt%for Al_2O_3.The SiO_2/Al_2O_3 ratios of all samples vary from 23.84 to 46.11, much lower than those of the pure cherts（80-1400）.These values suggest that the cherts contain high ratios of terrigenous materials.The Al_2O_3/（Al_2O_3＋Fe_2O_3）ratios vary between 0.64 and 0.77,whereas V and Cu concentrations range from 10.92 ppm to 26.7 ppm and from 2.15 ppm to 34.1 ppm respectively. The Ti/V ratios vary from 25.53 to 44.93.The total REE concentrations of the cherts are between 30.78 ppm and 59.26 ppm,averaging 45.46 ppm.The（La/Ce）_N ratios range from 0.81 to 1.12,and 0.88-1.33 for（La/Yb）_N,averaging 1.09,which suggests a continental margin environment.Consequently,it is inferred that the cherts formed in a residual sea environment during the late Devonian to early Carboniferous time,which suggests that the collision between the Karakum-Tarim and Kazakhstan-Junggar plates did not occur at the time.In addition,the regional geological information indicates that the study area experienced a post-collision stage during the early Permian,and thus it is likely that the collision between the two plates took place in the late Carboniferous.

The Origin of Bedded Cherts of the Early Permian Gufeng Formation in the Lower Yangtze Area, Eastern China

Bedded cherts occurring in the Early Permian Gufeng Formation in the Lower Yangtze region, eastern China, are nearly 20-80 m in thickness and contain varying amounts of radiolarians and sponge spicules. There are three types of section for the Gufeng Formation: chert, carbonate and chert-carbonate mixing types. Bedded cherts mainly occur in the first and third types of section. The depocentres of silica are marked by some small (not larger than a few thousand square kilometres in area) rhombic or elliptic hollows and their formation was controlled by faults. Argillaceous volcanic rocks in cherts occur as numerous thin layers. Bedded cherts are characterized by higher Fe and lower Al contents, enrichment in such trace elements as As, Sb, Bi, Ga, Au, Ag and Cr, lower total REE abundance, negative Ce anomaly and varying degrees of HREE enrichment. These characteristics are important evidence for hydrothermal cherts. Minor amounts of substances of non-hydrothermal origin are mixed in the cherts. The temperatures of sea water range approximately from a few tens of degrees to over 160℃. during the deposition of siliceous sediments.

Sedimentary Paleoenvironment of the Eastern Hexi Corridor, NW China: Constraints from Chert Geochemistry and Sedimentary Analysis of Early Paleozoic Strata

The eastern Hexi Corridor, northwest China, is located at the tectonic junction of the Alxa Block, the North China Craton, and the Qinling-Qilian Orogen. The early Paleozoic Xiangshan Group record critical information regarding paleoenvironment, paleoclimate and paleotectonic setting, from which we here present a focused study on the chert beds within the Xiangshan Group. Through field mapping, microstructural observation, whole-rock geochemistry analyses and detrital zircon dating, we suggest that the Xiangshan Group chert was deposited along a passive continental margin, formed primarily through biological activity with minor hydrothermal influence and terrestrial input. The characteristics of the chert support a low latitude sedimentary paleoenvironmental origin, and reveal the fact that the Alxa Block was separated from the North China craton, while emerged some paleogeographic affinity with the Qilian region in the Middle-Late Cambrian.

Reexamination of Radiolarian Biostratigraphy in Permian in Pelagic Chert Sequences at Dachongling Section, South China

Permian radiolarian biostratigraphy was reexamined in the bedded chertsection in Qinzhou area of southeast Guangxi Zhuang Autonomous Region, South China. On the basis ofthe analyses of characteristic radiolarian composition, six radiolarian zones are recognized,namely, Pseudoalbaillella longtanensis Zone, Pseudoalbaillella globosa Zone, Follicucullusmonacanthus Zone, Follicucullus scholasticus Zone, Follicucullus charveti Zone and Neoalbaillellaornithoformis Zone, in ascending order. Correlation of these radiolarian zones with those in Japanis presented. The Neoalbaillella ornithoformis Zone was firstly discovered in Dachongling Section,which may indicate that pelagic chert of the late Permian existed there, according to theco-occurring conodonts.

Geochemistry of upper Permian siliceous rocks from the Lower Yangtze region, southeastern China:implications for the origin of chert and Permian ocean chemistry

The Permian Chert Event is of great significance to understanding the geological evolution of the entire Permian; however,the origin of widespread chert formation is debated. We report new geochemical data from deep-marine siliceous rocks of the upper Permian Da-long Formation, Lower Yangtze region, southeastern China. Their geochemical results show that these thin-bedded siliceous rocks have a clear biologic origin, with rare to no evidence of hydrothermal influence. The values of Al/(Al + Fe + Mn) and Eu/Eu~* are 0.60-0.84(mean = 0.72) and 0.45-1.08(mean = 0.77), respectively, and Mn/Ti ratios are relatively low(mean = 0.72). The correlations of LaN/CeN, LaN/YbN, and Fe203/Ti02 with Al_2 O_3/(Al_2 O_3 + Fe_2 O_3), along with the Ce anomaly, indicate that the Da-long siliceous rocks were deposited at a transitional zone between a continental margin and the open ocean; i.e., relatively close to terrestrial sediment input and far from hydrothermal activity. The accumulation of chert is related to its unique paleogeographic location in an equatorial setting with many submarine paleo-highlands.Intense upwelling and frequent local volcanism are the main factors that promoted the development of siliceous rocks in the studied area. Ocean acidification triggered by large-scale volcanism(Large Igneous Province) during the late Permian led to extensive silica precipitation and preservation.

Geological and Geochemical Characteristics of the Cherts in the Mojiang Gold Deposit and Their Implications

Geological and geochemical characteristics of cherts of the low\|middle parts of the Jinchang Formation indicate that cherts are associated with hydrothermal sedimentation, but the middle\|upper parts of the Jinchang Formation are mixed with normal sediments. The cherts are characterized by high Fe, As, Sb, Bi and Ga, low Al and total REE, negative Ce anomaly and HREE enrichment. Their \{δ\{\}\+\{18\}O\} values show that the forming temperatures of the cherts range from 128 ℃ to 146 ℃.

Geochemical Criteria of the Upper Sinian Cherts of Hydrothermal Origin on the Southeast Continental Margin of the Yangtze Plate

The Upper Sinian bedded cherts are widely distributed on the southeast continental margin of the Yangtze plate, with a total thickness ranging from 20 to 150 m. The cherts are very simple in chemical composition, with the contents of siliceous minerals exceeding 90% and those of other mineral species being very low. The total content of trace elements is considerably variable. The contents of most trace elements are low as compared with their crust clarke values. But these cherts are very rich in the trace elements Ba, As, Ab, Ag and U, coupled with relatively high contents of Fe, Mn and low contents of Al, Ti, and Mg. It can be identified as the cherts of hydrothermal origin in terms of the values of Fe/Ti, (Fe+Mn)/Ti, Al/(Al+Fe+Mn) and U/Th. In the Al\|Fe\|Mn, and Fe\|Mn\|(Cu+Ni+Co)×10 diagrams and lg \\|lg\, Cr\|Zr diagrams, all the samples from the area studied fall within the hydrothermal sediment field. All these characteristics show that the cherts are mainly the product of hydrothermal processes. The fact that the \{δ\{\}\+\{30\}Si\} values of the chert range from 0.0‰ to \{0.7‰\} with \{δ\{\}\+\{18\}O\} from 20.1‰ to 23.6‰ clearly manifests that the submarine hydrothermal water is the main source of silica.\;\;

Characteristics of Rare Earth and Trace Element Patterns in Bedded Cherts from the Bottom of the Lower Cambrian in the Northern Tarim Basin, Northwest China and Their Genetic Significance

The sedimentary sequence of the Lower Cambrian is a key interval to reveal the early evolution history of the Earth and there occur widespread cherts worldwide. These cherts possibly carry important information to decipher the breakup process of the Rodinia Continent. Black rock series at the bottom of the Lower Cambrian in the Northern Tarim Basin, China, is composed of black shales interbedded with thin-bedded cherts. Ten chert samples were systematically collected from two outcrops at Xiaoerbulak and Sogatbulak, 8.8 and 7.5 m thick respectively. The cherts were crushed, and were analyzed for trace element and rare earth concentrations. Trace elements such as V, Cu, Zn, U, Pb, Ba, Cd, Ag, Mo, As and Sb are highly enriched, and others such as Rb, Zr, Cs, Hf, Ta, W, Tl, Bi and Th are highly depleted in the cherts. These trace element patterns suggest that the cherts may be of deep crustal origin. The low ratios of Th/U and Rb/Sr further suggest that the cherts are of earth interior sources or received hydrothermal input during their deposition. Chondrite- normalized Eu/Eu* value markedly decreases upward in the section from 5.54 at the lowermost to 0.73 at the top, and NASC-normalized Eu/Eu* value decreases from 8.05 to 1.03. The relatively high Eu/Eu* ratio for the cherts from the northern Tarim Basin is most likely due to a hydrothermal input (e.g., Eu/Eu* ~10). The systematic decrease of Eu/Eu* ratio from the bottom to the top of the section reflects that the hydrothermal input is the largest in the lowermost portion of the section and gradually decreases upward. The chondrite-normalized Ce/Ce* ratio ranges from 0.42 to 0.83, with an average of 0.60. North American Shale Composite (NASC)-normalized Ce/Ce* ratio ranges from 0.42 to 0.79, with an average of 0.57. Negative Ce anomalies are distinct. ΣREEs in the cherts generally increase from 10.50 ppm at the bottom to 35.97 ppm at the top of the sampled section. NASC-normalized (La/Lu) N ratio decreases from 2.72 at the bottom to 0.67 at the top. NASC-normalized (La/Ce) N ratio increases from 1.36 at the bottom to 3.13 at the top. These REE patterns are very similar to those for the cherts deposited in the pelagic ocean-basin floor in the Franciscan Complex exposed at Marin Headlands, California (F-MH chert) (Murray et al., 1991). These geochemical signatures are inconsistent with our previous sedimentological data, which suggests a continental shelf setting. Based on multiple lines of evidence including high TOC content in the concomitant black shales, phosphorite at the bottom of black rock series, regional rise of sea level, and beginning of the southern Tianshan Ocean geotectonic cycle, the authors infer that the hydrothermal fluid was carried to the continental shelf by upwelling from a divergent pelagic ocean floor setting.

The infrastructure and Origin of Upper Sinian Cherts on the Southeast Continental Margin of the Yangtze Platform

Through microscopic and SEM observations and X-ray diffraction and energy spectrum analyses, the oldest sponge spicules and radiolarians have been found in bedded cherts and it is proposed that microbial activity of algae and bacteria played an important role in silica precipitation. The microbial activity resulted in the formation of a series of single crystals and crystal aggregates with peculiar shapes. Biogenic single crystals usually occur in spherical, rod, platy, colloidal and granular forms. The most common aggregates are framboidal aggregates composed of dense spherical quartz crystals, which are considered to be of typical bacterial origin. Other aggregates, such as favositic, double-spherical, chain-spherica'l and coccoid ones, are considered to be probably the result of silicification of algal cells and mainly of primary sedimentary origin. This paper also discusses the ultrastructural features and diagnostic indications of jasper rocks formed in a submarine hydrothermal environment and cherts formed by replacement and diagenetic recrystallisation.

Comparative geochemical study of the cherty rocks of the Taukha terrane(Sikhote-Alin)and its paleogeodynamic significance

The article presents the results of a comparative geochemical study of cherts and siliceous-clayey rocks composing the tectono-sedimentary complexes of various structural levels of the Taukha terrain of the Sikhote-Alin Late Jurassic-Early Cretaceous accretionary prism.The data obtained show that the same-aged parts of the crosssections of the cherty-terrigenous sequences of the terrane lower and middle structural levels are characterized by significantly different contents and distribution patterns of major petrogenic oxides,trace,and rare-earth elements due to their accumulation in various facies of oceanic zones.The set of geochemical data indicates that the formation of both tectono-sedimentary complexes was carried out differently,gradually replacing each others’facies oceanic zones,and started in the near-spreading ridge area,then in the pelagial,and completed in the continental-margin deposition environment.Based on the time interval of the facies conditions changing for each complex(i.e.,time of transition from one facies zone to another),the speeds of a paleo-oceanic plate motion(and,correspondingly,the speeds of spreading)for individual intervals of the Jurassic were calculated.Differences in the spreading speeds at various sites of a paleorift zone caused the turning of a paleocontinent margin contour and spreading ridge axis at the perpendicular position,which in turn caused change of the geodynamic mode on the eastern margin of the PaleoAsian continent at the Jurassic-Cretaceous transition.

GeochemicalFeaturesandFormationoftheAuriferousChertsintheMojiangGoldDeposit,Yunnan

Auriferous cherts in the Middle Carboniferous Jinchang Formation are the dominant host rocks of auriferous quartz veins and mixed orebodies comprised of gold\|bearing quartz veins and cherts in the Mojiang gold deposit. The rocks exhibit sedimentary texture and structure and are composed of hot\|water deposited minerals. The FeO, Fe\-2O\-3, Au and Ag contents of the auriferous cherts are high; the Cr, Ni and Co contents are also high but significantly variable; MnO/TiO\-2 and TFe/TiO\-2 ratios are relatively high. As viewed from a few diagrams that distinguish different chert formations, the auriferous cherts are in or near the range of hot\|water deposited cherts. Because the correlation coefficients between Au contents and those of Cr, Ni of the rocks are negative, a great Au amount in the cherts might not be brought about by later hydrothermal alterations. The rare\|earth elements, O and Si isotopic compositions of the auriferous cherts demonstrate that the cherts belong to hot\|water deposited rocks. The later hydrothermal alterations made the petrochemical compositions of the cherts deviate from the characteristics of hot\|water deposition. In general, the geological and geochemical features of the auriferous cherts demonstrate that the rocks were formed by hot water deposition.

Land-Ocean Linkage: Pelagic Cherts in Mesozoic Neritic-Terrestrial Sequences in East Asia

Chert clast-bearing epi-continental neritic-terrestrial Jurassic and Cretaceous sequences are sporadically distributed in southwestern Japan. Typical and geological entities are the Torinosu Group and Tetori Group. Radiolarian dating of chert clasts enables us to discuss denudation stages of mid Mesozoic accretionary complexes. Chert clast-dominated conglomerate can be used for identifying marine beds within terrestrial sequences.

Biogenic characteristics of Mesozoic cherts in southern Tibet and its significance

The Xialu chert, which contains abundant biological information, were investigated by major element analysis, micro-Raman, SEM and EPMA. The results show that SiO2 content of chert is 84.12%-93.08%, averaging 89.84%. The close packed structures of low degree crystallinity of quartz indicate the hydrothermal origin. SiO2 of modern hot springs exhibit loose silica pellets and nodular, beaded structures. Under polarization microscope, the presence of biological skeleton structures indicate that biological activities are involved in the hydrothermal deposition, which correspond to the geochemical characteristics: w(SiO2)/ w(K2O+Na2O), w(SiO2)/w(Al2O3) and w(SiO2)/w(MgO), with average values of 295.29, 68.88 and 284.45, respectively. SiO2 is enriched in the organism(radiolarian) centers, the degree order of SiO2 within the biologic structures is much higher than that of outside. The impurity minerals albites are formed earlier than the original deposition. Kaolinites, feldspars and mixture of organic materials display lower degree of crystallinities and accumulate as vermicular aggregates.

GRANITOIDS,VOLCANIC ROCKS AND CHERTS FROM NORTH ALTYN TAGH,NW CHINA: IMPLICATION FOR THE TECTONIC ENVIRONMENT DISCRIMINATION

Granitoids,volcanic rocks and cherts,mainly of early Paleozoic,in northern Altyn Tagh(Fig.1) are analyzed here for the purpose of the determination of the tectonic environments and their development since Early Paleozoic.(1) Granitoids\ The collection of 128 main\|element petrochemical data from North Altyn Tagh area shows that most of the granitoids here are granites and granodiorites of calc\|alkaline series.They consist mainly of metaluminous and peraluminous in Shand’s index,and only one of them,which belongs to Mesozoic,is peralkaline.Most of the granitoids plot in the IAG+CAG+CCG fields in the Maniar and Piccoli’s diagrams (1989) for tectonic discrimination of granitoids.IAG (Island arc granitoids)and CAG (Continental arc granitoids) can be distinguished for Early and Late Paleozoic granitoids,and maybe some CCG (Continental collision granitoids) for Early Paleozoic.Granitoids of Mesozoic and Cenozoic inherited the characteristics of those of Paleozoic.Destructive active plate margin (pre\|plate collision)and Anatectic magmatism(syn\|orogenic,S\|type granites)are distinguished (Fig.2)for Paleozoic granitoids using de la Roche R 1\| R 2 multicationic diagram (Batchelor and Bowden,1985).Mesozoic and Cenozoic granitoids inherited the characteristics of Anatectic magmatism (syn\|orogenic)of these early ones,and post\|orogenic(A\|type)granites occurred in Mesozoic.The mechanism for magma formation is mainly partial melting.