【作者】 杨江海；

【导师】 杜远生；

【作者基本信息】 中国地质大学 ， 古生物学与地层学， 2012， 博士

【副题名】以北祁连志留系、右江二叠—三叠系和大别山南麓侏罗系为例

【摘要】 当今地球科学的两大主题是地球动力学和全球气候变化。位于板块边界的造山带是全球构造、岩浆和变质等地质作用最为活跃的地区之一；同时也是地表系统物理、化学活动最为强烈的结构单元之一。因此,造山带的形成、演化和发展是地球动力学前沿科学问题之一。当前造山带研究已经发展成为一个多学科、多角度和多时空的综合性学科方向,以全面阐释构造、岩浆、变质、沉积和动力为研究目标。其中,造山带沉积地质学研究逐渐成为新研究思路的增长点和问题解决的突破口,是造山带(如喜马拉雅)研究的一个重要方向。造山带来源的物质被搬运至周缘各种盆地中沉积下来,这些沉积物蕴含有丰富的源区信息,同时又被赋予特定的地层时代,为重建造山带演化历史提供重要依据。本文即是从造山带沉积地质学角度出发,利用相关的碎屑沉积记录来反演造山带的形成和发展,并通过三个实例研究,探讨造山带特定演化阶段的碎屑沉积响应。选取的三个研究实例分别为中国西北部北祁连志留系、西南部右江二叠-三叠系和大别山南麓侏罗系。北祁连志留系下覆为弧后盆地火山-沉积序列,并被泥盆系磨拉石不整合覆盖,是华北克拉通南缘早古生代从大洋俯冲到大陆碰撞转换的关键地质记录。右江二叠-三叠系记录从被动陆缘盆地到前陆盆地的转换,是华南大陆西南缘印支造山作用的重要物质记录。大别山南麓侏罗系对应于大别山的折返隆升,是大别山早期剥露历史的记录。本论文重点采样层位包括北祁连下志留统、右江上二叠统-中三叠统和大别山南麓中下侏罗统,主要样品为砂砾岩、砂岩、粉砂岩和泥岩等碎屑岩,以及右江盆地相关的火山岩和凝灰岩。通过中粗粒和中细粒砂岩的碎屑组分、碎屑岩全岩地球化学、碎屑锆石U-Pb年龄组成和重矿物(锆石和尖晶石)化学成分分析,获得大量与源区组成和性质相关的物源数据。祁连造山带位于青藏高原的东北端,记录了华北克拉通、中祁连地块和柴达木地块早古生代的相互作用。北祁连带位于该造山带北部,是华北克拉通南缘与中祁连地块间碰撞拼合的结果。北祁连下志留统碎屑岩的主要物源区为北祁连早古生代火山弧、中祁连地块的元古代基底和华北克拉通太古代基底及其再旋回沉积物。西部下志留统下部和东部晚奥陶统上部-下志留统下部既有来自早古生代弧火山岩的碎屑,也有来自南北大陆基底的碎屑,而下志留统上部碎屑主要来自南北陆块基底岩石。在西部下志留统下部砂岩中发现有来自SSZ(超俯冲带)型蛇绿岩的碎屑尖晶石,表明北祁连洋的洋壳残片已经仰冲至地表遭受剥蚀。早古生代年龄的碎屑锆石整体具有地壳岩石中锆石的地球化学特征,但少数几个颗粒落在洋壳锆石和陆壳锆石的重叠区,可能与碎屑尖晶石具有相似的超俯冲带洋壳性质的源区。结合岛弧火山岩、岛弧I型花岗岩、高压/低温榴辉岩-蓝片岩、同碰撞S型花岗质岩石、后碰撞I型花岗质岩石和大陆深俯冲超高压变质岩的年代学研究,北祁连下志留统的物源组成表明,祁连造山带地区早古生代从大洋俯冲到大陆初始碰撞的转换发生于奥陶纪末-早志留世初期(～450—440Ma)。右江盆地西北部紧邻峨眉山玄武岩省,东部和北部与扬子碳酸盐台地相接,东南为南华造山带,西南与越北地体以八布缝合带相隔。该盆地晚古生代以特征的深水盆地相和浅水孤立台地相相间沉积为特征,受北西向和北东向两个断裂系统控制,从南到北,可分为那坡、百色和河池-南丹-紫云三个次级盆地。晚二叠世-中三叠世盆地相沉积为火山岩屑浊积岩、硅质岩、泥岩和陆缘碎屑浊积岩及泥灰岩、钙质砂岩和砾屑灰岩。右江晚二叠世碎屑岩具有类似于峨眉山高Ti玄武岩的地球化学特征,砂岩中含有大量基性玄武岩岩屑,同时锆石U-Pb年龄也与峨眉山大火成岩省的主要岩浆喷发期一致,锆石颗粒具有类似于板内/非造山环境岩浆结晶锆石的微量元素特征,表明峨眉山高Ti玄武岩为主要物源区,且碎屑沉积于华南大陆西南部被动大陆边缘。地层对比和古流向等资料也支持火山碎屑主要来自盆地西北部峨眉山玄武岩的结论,而且碎屑沉积岩的地球化学组成表明这一主要物源区可能一直持续到早三叠世早期。早三叠世晚期物源发生重大变化,岩石地球化学组成明显不同于晚二叠世-早三叠世早期沉积岩,且砂屑灰岩中首次出现来自火山弧的二叠纪年龄的碎屑锆石。二叠-三叠纪界线附近凝灰岩地球化学和锆石U-Pb年龄及微量元素组成表明,此时由金沙江-哀牢山-八布洋盆南西向俯冲产生的岩浆弧已经靠近华南大陆西南缘；而早中三叠世界线附近凝灰岩及火山岩地球化学和锆石U-Pb年龄及微量元素组成则指示,它们形成于同碰撞环境,表明该岩浆弧与华南大陆沿金沙江-哀牢山-八布缝合带发生碰撞。中三叠世,右江盆地成为充填来自造山带的大量浊流碎屑的前陆盆地。右江盆地从被动陆缘向前陆盆地的转换发生于早三叠世(～250—245Ma)。大别山南麓黄石地区早中侏罗世为河流相碎屑沉积,在垂向上表现为旋回性的砂岩、粉砂岩和泥岩组合,包括曲流河河道、点坝和洪泛平原沉积的武昌组和辫状河河道和河道间沉积的花家湖组。古流向和物源数据表明,水流体系以向西流动的携带华南大陆基底碎屑的纵向水流为主,并混有向南流动的来自北部大别山的横向水流,且后者在中侏罗世明显增强。锆石REE及LC图像研究显示,早侏罗世砂岩中存在奥陶纪末期麻粒岩相变质锆石,而中侏罗世砂岩不但含有奥陶纪变质锆石,而且出现石炭纪榴辉岩相变质锆石和对应于大别山三叠纪高压／超高压变质作用的碎屑锆石。这一结果表明大别山曾发生早古生代麻粒岩相和石炭纪榴辉岩相变质事件,且相关高级变质体已于早中侏罗世折返剥露地表。同大别山北麓合肥盆地和东部潜山地区同时期碎屑锆石数据对比表明,大别山高压/超高压变质岩石在北部剥露较早(早侏罗世)而南部较晚(中侏罗世)。此外,黄石早中侏罗世砂岩、东部潜山早中侏罗世砂岩与韩国和日本相似构造位置(高压／超高压变质带南部)的同时代碎屑沉积物具有一致的碎屑锆石年龄组成,表明随大别超高压变质带经苏鲁变质带向东延伸至韩国和日本,其南部的前陆盆地系统也可能存在类似的延伸。北祁连下志留统记录了华北克拉通南缘从活动陆缘向前陆盆地的转换,右江盆地晚二叠世-中三叠世则记录了华南大陆西南缘从被动陆缘到前陆盆地的转换。由于所处的构造背景的不同,北祁连早志留世和右江早中三叠世碎屑沉积对初始碰撞造山作用的沉积响应也有所差别。初始碰撞造山作用在北祁连下志留统的碎屑沉积记录为：(1)华北克拉通和中祁连地块同时提供物源；和(2)造山带来源的碎屑的出现,如反映蛇绿岩遭受剥蚀的碎屑尖晶石和高Cr地球化学特征。初始碰撞造山带作用在右江盆地的记录为：(1)火山弧来源的碎屑沉积在华南西南被动陆缘之上；和(2)反映洋壳深俯冲作用的榴辉岩相变质岩已经折返到地表,并为右江盆地提供碎屑。这种沉积记录的差别反映了前陆盆地的形成在一定程度受构造背景的控制。在大别山隆升过程中,高压／超高压及其它高级变质岩折返剥露至地表的记录为黄石盆地中下侏罗统砂岩中对应年龄变质碎屑锆石的出现：奥陶纪末麻粒岩相变质锆石在下侏罗统砂岩中的出现表明早古生代麻粒岩相变质体折返剥露地表的时间在早侏罗世或之前；石炭纪榴辉岩相变质锆石和三叠纪变质锆石在中侏罗统砂岩中开始出现,表明高压/超高压变质岩折返剥露地表的时间为中侏罗世。利用盆地碎屑沉积来研究造山带折返隆升具有一个显著优势,即这些碎屑记录保存于一定的地层序列中,从而使造山带隆升过程被赋予相对或绝对的时间属性。同时,如果地层保存较为完整,那么这种时间属性就是连续的,所记录的动力过程也将是动态的、长时间尺度的。黄石盆地碎屑沉积对大别山折返隆升过程的重要性也正在于此。此外,对包括黄石盆地在内的大别山周缘前陆盆地同时代碎屑记录的对比研究则反映大别山隆升过程的空间属性。获得有效的与造山带碰撞-隆升过程相关的碎屑沉积记录的关键在于准确而可靠的物源分析,这就要求高精度的物源分析方法。碎屑沉积岩的组成受原岩性质、风化强度、沉积分选、再旋回程度、成岩作用和变质强度等因素的综合控制,与构造背景间不存在直接的联系。因此,传统物源判别图解的低成功率实际反映的不仅是图解本身的问题,而且也是碎屑沉积物组成和形成过程的复杂性。如果不考虑沉积后的成岩和变质影响,那么控制沉积物组成的要素则为原岩组成和沉积过程。对传统地球化学构造环境判别图解和砂岩碎屑模式三角图解的局限性研究表明,特殊的物源组成和沉积过程是影响这些传统物源分析方法有效性的主要因素。由于碎屑沉积物的形成直接受控于源区性质和沉积过程,因此,在利用这些模式判别图解时一定要谨慎而行,它们可能给出完全错误的结论。相对于砂岩来说,泥岩以高Al2O3、Fe2O3+MgO、Al2O3/SiO2、Th/Zr、Ti/Zr、La/Y和Sc/La为特征。它们具有相似的La/Th、Th/Sc和Sc/Cr等比值,表明整体来源自同一属性的源区,但化学风化、沉积分选和再旋回过程使一些元素随粘土矿物等比重低和粒径小的碎屑颗粒富集于泥级沉积物中,而一些元素随锆石等比重大和粒径较粗的碎屑颗粒在砂级沉积物种富集。大陆溢流玄武岩可以作为被动陆缘碎屑沉积的主要物源,使形成于被动陆缘的碎屑岩含有大量的玄武质岩屑,例如江盆地晚二叠世-早三叠世早期的碎屑沉积岩,它们沉积于华南大陆西南被动大陆边缘,由于峨眉山玄武岩源区的存在,使这些沉积物在构造背景图解中落在大洋岛弧／大陆岛弧／活动陆缘区。相对于这些传统物源分析方法,单颗粒矿物源区分析技术则可以提供更为详细和准确的物源信息。锆石U-Pb年代学已经被广泛用于碎屑沉积物的源区分析,但对其化学成分的物源指示意义仍存在较多的争议。在本文的三个研究实例中,尝试运用锆石微量元素组成来示踪特殊的源区,讨论其成因类型、岩浆性质和构造背景,如蛇绿岩、高压／超高压变质岩和裂谷／板内岩浆岩,表明它可以作为锆石物源分析的重要组成部分。需要指出的是,通过比较弧／造山带岩浆结晶锆石与板内/非造山岩浆结晶锆石在微量元素含量及比值的差异,建立判别两类锆石的双变量图解,为利用锆石化学组成示踪岩浆活动类型及构造背景提供了依据,这是本文的创新点所在。更多还原

【Abstract】 Geodynamics and Global Climate Change are two major issues in current earth science. Built upon the plate boundaries, orogen is one of the places with most active geologic processes including tectonic movement, magmatism and metamorphism in the world, and also one of the elements with violent physical and chemical activities in the earth surface system. Therefore, the orogenic process constitutes pivotal part of the Geodynamics. This requires the orogen to be studied synthetically by multi-disciplinary, multi-sided and time-space viable methods, with the aim to investigate and understand the history of tectonics, magmatism, metamorphism and dynamics involved. Among the methods, utilizing detrital records is now proven efficient to provide new clues and new resolutions to the problems related to the orogenic evolution (such as in Himalaya Orogen). The sediments dispersed from the orogen and deposited in the adjacent basins contain lots of information pertinent to their provenance, which will become very particular as the temporal stratigraphic framework can be constrained. In this dissertation, three examples from China will be studied to show how to employ detrital records to unravel the orogenic processes and then discuss the sedimentary responses to initial collision and exhumation of HP/UHP metamorphic rocks.The studied three examples are the North Qilian Silurian sediments in the NW China, the Permian-Triassic sediments of Youjiang Basin in SW China and the Huangshi Jurassic sediments south of the Dabie Mountains in Central China. The North Qilian Silurian clastic rocks, underlain by the Ordovician back-arc volcano-sedimentary sequences and overlain by the Devonian molasses, are the records of the early Paleozoic tectonic transition from ocean subduction to continent collision in the southern North China Craton. The Youjiang Basin evolved from a passive marginal basin to a foreland basin during the Permian-Triassic time, a sedimentary sequence related to the Indosinian orogny in the SW South China Block. The Jurassic clastic sedimentary rocks in Huangshi Basin south of the Dabie Mountains are the records of the mountain building, and combined with the equivalent sediments in other basins around this mountain, can constrain the exhumation history of the Dabie Orogen. The studied samples are from the North Qilian Lower Silurian, the Youjiang Upper Permian-Middle Triassic and the Huangshi Lower-Middle Jurassic south of Dabie Mountains, including conglomerate sandstone, sandstone, siltstone, and shale. In addition, in Youjiang Basin Triassic volcanics and tuffs were sampled as well. By combing analysis of sandstone detrital modal composition, whole-rock geochemistry, detrital zircon U-Pb ages and heavy mineral chemistry (Cr-spinel and zircon), amounts of provenance-bearing data are obtained.The Qilian Orogen is situated in the northernmost part of the Tibet Plateau, with its formation related to the interaction between North China Craton, Central Qilian Block and Qaidam Block. Constituting the northern part of this orogen, the North Qilian Belt records the collisional assembly of southern North China Craton with Central Qilian Block. The Lower Silurian sediments in North Qilian were mainly sourced from the North Qilian early Paleozoic volcanic arc, the Proterozoic basement of the Central Qilian Block and the Archean basement and its recycled materials of the North China Craton. The lower Lower Silurian in the western segment and the upper Upper Ordovician-lower Lower Silurian in the eastern segment contain detritus from both the early Paleozoic arc volcanics and the continental basement rocks of the Central Qilian Block and the North China Craton. In contrast, continental basements are the main detrital supplier to the upper Lower Silurian sediments with the arc-derived component insignificant. Detrital spinels are observed in the western Lower Silurian sandstones, and have chemical composition similar to that of those from SSZ (supra-subduction zone) type ophiolites, suggesting that the North Qilian oceanic crust has been obducted and eroded. Detrital zircons of early Paleozoic ages are overall comparable to those of continental crust in geochemistry, with a small group of them plotted in the overlapping filed between the continental crust and oceanic crust zircons on the zircon trace element discriminating diagrams. The latter may be derived from a similar ophiolitic source as the detrital spinels. Combined with age data from arc volcanics, arc-related I-type granitic rocks, UP/LT eclogites and blueschists, syn-collisional granitic rocks, post-collisional I-type granitic rocks and continental deep subdction HP/UHP metamorphic rocks, the provenance of the North Qilian Lower Silurian clastic rocks suggests that the tectonic transition in Qilian Orogen from ocean-subduction to continental collision occurred during the latest Ordovician-earliest Silurian time (～450-440Ma)。The Youjiang Basin located in SW China, with the Emeishan basalt province to the northwest, Yangtze carbonate platform to the north, and Nanhua orogen to the east. This basin is separated from the North Vietnam to the southwest by Babu suture zone. During the late Paleozoic-Early Triassic, the sedimentation in this basin is characteristic of alternating deep-water basinal and shallow-water isolated carbonate platform sequences, controlled by northwest-southeast and northeast-southwest fault systems. As such, the Youjiang Basin can be divided into three NW-trending belts, named Napo, Baise and Hechi-Nandan-Ziyun sub-basins in a south to north order. The Late Permian-Middle Triassic strata are composed mainly of clastic turbidites, cherts, mudstones, marls, calcarenites and breccias. The Late Permian sediments have similar geochemical characteristics to the Emeishan high-Ti basalts, the sandstones contain plenty of basaltic rocks fragments, the zircons yield U-Pb ages are consistent with the main eruption stage of the Emeishan Large Igneous rocks and are characteristic of geochemical affinity to those from within-plate/anorogenic rocks, suggesting that Emeishan high-Ti basalts are the major source component and these rocks deposited in the passive margin of SW South China Block. This provenance interpretation is supported by the Late Permian stratigraphic correlation and paleo-current data, and such detrital flux may continue into the early stage of the Early Triassic as indicated by the sedimentary geochemistry. The provenance of the late Early Triassic sediments, however, are changed totally, as suggested by that the sediments have distinctly different geochemistry from the Late Permian-early Early Triassic clastic rocks and volcanic-arc sourced detrital zircons with Permian ages are present in the calcarenites. The geochemistry and zircon U-Pb ages and trace elements of the tuff rocks near the P/T boundary suggest that the magmatic arc is approaching to the South China Carton due to the southwestward seduction of the Jinshanjiang-Ailaoshan-Babu Paleo-Tethyan Ocean, while the Early-Middle Triassic tuffs and volcanics correspond with the subsequent collision. In the Middle Triassic, Youjiang Basin was flooded by turbidity detritus from the surrounding orogens. Therefore, conversion of Youjiang Basin from a passive marginal basin to a foreland basin occurred during the Early Triassic (～250-245Ma).The Lower-Middle Jurassic in Huangshi south of Dabie Mountains is a reverie sequence of recycled sandstone, siltstone and mudstone, including channel, point-bar and floodplain sedimentation in a meandering river for the Early Jurassic Wuchang Formation and channel and inter-channel sedimentation in a braided river for the Middle Jurassic Huajiahu Formation. Paleocurrent and sandstone provenance data suggest that a truck river flowed westward carrying detritus from the South China Block Paleoproterozoic basement and southward tributaries drained the Dabei orogen, with the latter getting stronger in the Middle Jurassic time. Detrital zircon U-Pb ages, CL images and REE elements suggest that one granulite-facies metamorphic zircon with latest Ordovician age is present in the Early Jurassic sandstone, while the Middle Jurassic sandstone contain not only the Ordovician metamorphic detrital zircons but also Carboniferous eclogite-facies metamorphic zircon and Triassic detrital zircons of metamorphic origin, which overlapping in age with the Triassic HP/UHP metamorphism in Dabie Orogen. This result suggests that in this source area occurred corresponding high-grade metamorphism, and such metamorphic terranes have been exhumed to the surface and eroded. Comparison with similar provenance studies from the northern Hefei Basin and eastern Qianshan Basin constrains a differential exhumation style by which the HP/UHP rocks were exposed earlier in the northern part and relatively latter in the southern part. In addition, the Early-Middle Jurassic sandstones in Huangshi Basin and Qianshan Basin yield a similar detrital zircon U-Pb spectrum, which can be correlated with those from the time-equivalent clastic rocks in southern Korea Peninsula and SW Japan, which occur in a comparable tectonic position (situated south of a HP/UHP belt). This data compilation leads supports for hypothesizing an elongated foreland basin south of the Dabie-Sulu collisional belt in China and its eastern extension in Korean and Japan.The Lower Silurian clastic sequence in North Qilian is a sedimentary record related to the early Paleozoic tectonic transformation from active continental margin of the North China Craton to a foreland basin, and the Late Permian-Middle Triassic clastic rocks in Youjiang Basin mark a basin conversion from a passive marginal basin in the SW South China Block to a foreland basin. The initial collisional sedimentary records in North Qilian Lower Silurian sediments include:(1) both the Central Qilian Block and North China Craton providing respective basement materials at this time; and (2) occurrence of orogen-derived detritus, such as detrital Cr-spinels and sandstones with high-Cr contents which argument for an ophiolitic provenance component. In Youjiang Basin, the evidences for initial collision include:(1) Permian volcanic-arc derived detrital zircons in the late Early-Middle Triassic clastic rocks which overlying the passive margin sequences; and (2) Carboniferous detrital zircon of eclogite-facies metamorphic origin occurred in the Middle Triassic sandstones, denoting the quick exhumation of the deep-subducted materials during the collision. The differences in the detrital record of initial collision from North Qilian and Youjiang examples, which have different pre-foreland basin tectonic positions, indicate that the formation and evolution of foreland basin is complicated and related to the tectonic background.Huangshi Lower-Middle Jurassic sedimentary record is a good indicator for the exhumation of Dabie Mountains. During the uplift of the Dabie Mountains, HP/UHP and other high-grade metamorphic rocks were exhumed to surface and recorded as detrital zircons in the Jurassic strata in Huangshi Basin, such as the occurrence of latest Ordovician aged detrital zircon of granulite-facies metamorphic origin in the Lower Jurassic sandstone representing that the early Paleozoic metamorphic terranes have been exhumed to surface by the Early Jurassic or earlier; the occurrence of Carboniferous and Triassic aged detrital zircons of eclogite-or high-grade metamorphic origins in the Middle Jurassic sandstone suggesting that corresponding HP/UHP rocks have been exhumed and exposed to the surface in this time. A significant superiority with implication of detrital record for mountain building is that these special detritus are preserved within a certain stratigraphic sequence, imposing a relative or absolute temporal feature on the orogen exhumation process. More importantly, if the sequence can be traced vertically, the corresponding record will be continuous and thus, reflect a dynamic process in a long-time interval. This is the significance of the study on the Huangshi Early-Middle Jurassic sandstones. In addition, provenance data compilation and comparison from the adjacent basins with Huangshi Basin included show a difference in the sedimentary record which reflects the time-space disequilibrium during the Dabie mountain uplift and exhumation.The key to get efficient sedimentary records related to the orogenic process is to obtain accurate and reliable provenance data, which depends on provenance analysis methods with high-resolution. The composition of clastic sedimentary rocks is the combined function of nature of provenance, chemical weathering, sedimentary sorting and recycling, post-depositional diagenesis and possible metamorphism, and not related directly to the tectonic setting. Considering this, the low success rate of routinely used tectonic discrimination diagrams reflects not only the intrinsic flaw of these diagrams, but also the complexity of sediment generation. If excluding the effects from diagenesis and metamorphism, sediments will be controlled compositionally by source components and sedimentary process. Based on the data of this dissertation, the limitation of the conventional whole geochemical and routine sandstone modal compositional discriminating diagrams was evaluated. It is concluded that special provenance component (e.g. continental flood basalts) and sedimentary process (chemical weathering, sedimentary sorting and recycling) are the main factors leading the results of such diagrams to be deviate from the actual what it is. Considering the composition of the clastic rocks are directly related to the nature of the source rocks and the intensity of chemical weathering, sedimentary sorting and recycling, it is recommended that these routine diagrams should be used with special cautions. Comparing with sandstones, the companying mudstones are characteristic of high contents in Al2O3and Fe2O3+MgO and high ratios of Al2O3/SiO2、Th/Zr、 Ti/Zr、La/Y and Sc/La. The difference can be ascribed to the sedimentary processes including chemical weathering, sedimentary sorting and recycling, by which some particals with low density and small size, such as clay minerals, will concentrate in muddy sediments and other particals with great density and large size, such as zircons and quartz, will be enriched in sandy sediments, a detrital sorting which will differentiate elemental distribution in sediments. Continental flood basalt can disperse voluminous mafic detritus into the adjacent passive continental margin, a kind of sediments totally different from quartzose deposits which are usually interpreted to represent a passive margin setting.Contrastingly, single mineral provenance analysis provides more detailed and valuable results. Among them, detrital zircon U-Pb geochronology now becomes a frequently-used method to infer the potential sources. However, its chemical significance to provenance is still under debate. In this dissertation, zircon REE pattern and other trace elements were used to discuss its origin (magmatic or metamorphism), metamorphic condition (if of metamorphic origin) and the nature and tectonics of related magmatism (if of magmatic origin), indicating that zircon chemistry could not be overlooked when studying detrital zircon provenance. To be noted is the designed diagrams using zircon trace elements to separate magmatic zircons from arc-related/orogenic setting from those from within-plate/anorogenic setting, which may be useful in future studies.更多还原