Metamorphic P–T Conditions and In–situ Rb–Sr Geochronology of the Kuanping Group in the Laoyu Area of the Qinling Orogenic Belt
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摘要:
秦岭造山带涝峪地区发育宽坪岩群的典型剖面,是研究宽坪岩群变质变形、构造热历史的重要区域。然而,由于缺乏对该地区宽坪岩群变质温压条件和年代学的约束,导致区域变质与多期变形事件的关系及地质意义认识仍不清楚。笔者以该地区宽坪岩群SN向剖面中的二云母石英片岩、含石榴子石二云母石英片岩、绿片岩和大理岩为研究对象,开展了详细的岩相学研究。在此基础上,重点对二云母石英片岩和含石榴子石二云母石英片岩进行了黑云母Ti温度计、多硅白云母地质压力计、变质相平衡模拟和原位LA–ICP–MS黑云母和白云母Rb–Sr年代学研究,进而探讨了涝峪地区宽坪岩群经历多期构造热事件的意义。野外和岩相学观察发现二云母石英片岩和绿片岩发生了强烈的变形,金云母大理岩经历了强烈的糜棱岩化作用。黑云母Ti温度计和多硅白云母压力计限定得到二云母石英片岩样品KP-3和KP-4的变质温压条件为300~500 ℃、2.0~8.0 kbar,对应的平均值为440 ℃、4.0 kbar。黑云母Ti温度计限定得到含石榴子石二云母石英片岩样品KP2202的变质温度为652~683 ℃。变质相平衡模拟P–T视剖面图计算得到二云母石英片岩样品KP-3和KP-4的变质温压条件为400~480 ℃和2.0~10 kbar;而含石榴子石二云母石英片岩样品KP2202的变质温压条件为645~680 ℃、8.0~9.0 kbar。综合地质温压计和相平衡模拟的结果,可以确定二云母石英片岩为绿片岩相变质作用的产物,而含石榴子石二云母石英片岩经历了低角闪岩相变质作用。原位LA–ICP–MS黑云母和白云母Rb–Sr分析显示二云母石英片岩记录两期等时线年龄,分别为~290 Ma和~155 Ma,而含石榴子石二云母石英片岩记录的等时线年龄为~110 Ma。因此涝峪地区宽坪岩群中的二云母石英片岩记录了3期等时线年龄,分别为~290 Ma、~155 Ma和~110 Ma。结合前人的研究结果,3期等时线年龄均代表了后期构造热事件的时代,其中~290 Ma的等时线年龄与古特提斯洋向北俯冲作用相对应,而~155 Ma和~110 Ma的等时线年龄可能与中生代时期北秦岭构造带发生强烈的变形和花岗岩岩浆活动导致的热重置有关。
Abstract:The laoyu area of the Qinling orogenic belt has a typical section of the Kuanping group, which is important for studying the metamorphism, deformation, and tectonothermal history of the Kuanping group. However, the metamorphic P–T conditions and chronology of the Kuanping group in this region are still lacking, which hinders our understanding of the relationship between its regional metamorphism and later deformation events, as well as their geological significances. In this study, detailed petrographic studies were carried out on two–mica quartz schist, garnet–bearing two–mica quartz schist, greenschist, and marble in the north–south section of the Kuanping group in this area. Based on this, the geological significances of multiple tectonothermal events that the Kuanping group in the Laoyu region underwent were examined with a focus on two-mica quartz schist and garnet–bearing two–mica quartz schist using Ti–in–biotite thermometry, phengite geobarometry, phase equilibrium modelling, and in situ LA–ICP–MS biotite and muscovite Rb–Sr dating. According to field and petrographic observations, two–mica quartz schist and greenschist were both significantly deformed, and phlogopite marble suffered strong mylonitization. The Ti–in–biotite thermometer and phengite geobarometer yielded the metamorphic PT conditions of 300~500 ℃ and 2.0~8.0 kbar (average values are 440 ℃ and 4.0 kbar) for the two–mica quartz schist samples KP-3 and KP-4. The Ti–in–biotite thermometry constrained the metamorphic temperature of the garnet–bearing two–mica quartz schist sample KP2202 to be 652~683 ℃. According to the PT pseudosection modeling, the metamorphic PT conditions of the two–mica quartz schists and and the garnet–bearing two–mica quartz schists are 400~480 ℃ and 2.0~10 kbar, and 645~680 ℃ and 8.0~9.0 kbar, respectively. On the basis of the results from the geothermobarometry and phase equilibrium modelling, the two–mica quartz schist is the consequence of greenschist–facies metamorphism, whereas the garnet–bearing two–mica quartz schist formed by low–amphibolite facies metamorphism. In–situ LA–ICP–MS biotite and muscovite Rb–Sr dating shows that the two–mica quartz schist records two isochron ages of ~290 Ma and ~155 Ma, while the garnet–bearing two–mica quartz schist records an isochron age of ~110 Ma. Consequently, the two–mica quartz schists in the Kuanping group of the Laoyu region record three isochron ages, which are ~290 Ma, ~155 Ma, and ~110 Ma. Combined with the results of previous studies, all three isochron ages represent the timings of late tectonothermal events, where the isochron age of ~290 Ma corresponds to the northward subduction of the paleo–Tethys Oceanic crust, while the isochron ages of ~155 Ma and ~110 Ma may be related to the intense deformation and thermal resetting caused by granitic magmatism in the North Qinling tectonic belt during the Mesozoic.
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陕南秦岭山区由于呈高山峡谷特征的地形地貌,岩体因强烈的构造活动及风化作用而十分破碎,且区内软弱变质岩系广泛分布,加上降雨强度大、频率高,导致滑坡、崩塌、泥石流等地质灾害极为发育,严重威胁区内生命、财产安全。因此,针对秦岭山区地质灾害进行大比例尺调查及易发性评价具有重要的实际意义。
滑坡易发性评价是基于统筹考虑多种诱发滑坡灾害发生的各项影响因素之间可能的相互组合关系(向喜琼等,2005),进一步对滑坡灾害发生的概率进行的量化等级划分。因此,进行预测精确度较高的易发性评价对区内避免生命、财产的损失具有决策指导意义。目前,许多定性和定量方法用于滑坡易发性评价,前些年常用的定性方法主要有自然历史分析法、工程地质类比法等(王杰等,2011)。定性法对滑坡易发性评价起到一定的推动作用,但仍存在局限性。定量的方法主要基于机器学习,如决策树(赵建华等,2004)、支持向量机(黄发明等,2018)、贝叶斯(Snoek et al.,2012)、神经网络(邱海军等,2012;邱维蓉等,2020)等。另外,近年来所流行的随机森林法以决策树为基本模型,通过构建不同特征的数据集,经过训练形成一系列具有差异性的决策树模型,由投票得分最多决定结果,具有极强的数据挖掘能力、不易过拟、且对异常值和噪声具有较好容忍度、可获取变量重要性等优点(李亭等,2014;吴孝情等,2017;张向营等,2018;刘坚等,2018;吴润泽等,2021)。
但是,这些传统的机器学习评价方法无法在完成当前训练任务的同时保留对上一个任务的记忆,难以形成知识的复用与泛化,造成易发性评价精度无法极大提升。深度学习是多任务学习,一方面可增强中间层的泛化能力,在不断的学习过程中积累、提高有效的知识表示;另一方面具有知识推理能力,突破了上述传统机器学习评价方法的局限性。有学者采用深度神经网络算法(Saro Leeet al.,2004;Dou et al.,2020)及卷积神经网络算法(Maher et al.,2020;Fang et al.,2020)与传统机器学习算法构建滑坡易发性评价模型并比较其预测结果,结果验证基于深度学习的模型精确度相较于传统机器学习算法有着极大的提升。上述算法需要获得大量的训练样本来构建评价模型,对人力、物力需求较高,限制其广泛的应用。针对此问题,有学者进一步提出深度随机森林算法(Zhou et al.,2017),该算法作为决策树的集成模型,具有较少的参数、深度特征提取和不同数据规模适用性的优势,已被广泛应用于图像分类、图像识别、语音识别等领域。因此,笔者采用深度随机森林算法构建易发性评价模型。
选取合理的评价单元是滑坡易发性评价的基础,目前相关评价常用的单元划分有栅格和斜坡单元。由于研究区位于秦岭深处,冲沟及河道密集分布,若斜坡单元想实现精准划分,难度相当大。另外由于不同斜坡滑坡数据分布不均,特别是存在多个滑坡点分布于同一个斜坡上的现象,当采用深度随机森林进行分析时样本数量偏少且同一斜坡上出现重复计算的现象,会导致评价结果不太合理。故采取栅格作为评价单元。
综上所述,充分考虑与发育滑坡的地方具有相似的环境也同时具有相似的趋势原理,笔者设计能够融合深度随机森林算法优点与栅格评价单元为一体的区域滑坡易发性评价方法,并于随机森林算法相对比,比较滑坡易发性评价预测的精度,为区域滑坡易发性评价提供一个新的方法和视角。
1. 研究区概况与研究方法
1.1 研究区地质概况
研究区位于陕西省汉中市略阳县城的主城区,地理坐标为N 106°3′45″~106°15′00″,E 33°20′00″~33°25′00″(图1),面积约为165.68 km2。地形地貌总体以高山狭谷为主,可进一步分为剥蚀山地和侵蚀与堆积河谷地貌。周边多条强烈活动断裂和不同期次的褶皱发育,以勉县断裂和勉县–洋县断裂带为主。新构造运动继承第三纪末喜马拉雅运动,以上升运动为主,河流不断下切,形成高山狭谷。研究区出露的地层主要有元古界碧口群、震旦系、古生界志留系、泥盆系、石炭系及各期火成岩和新生界第四系。近年来,随着山区城镇化和新农村建设的加快,山区城镇建设规模的扩张,山区城镇建设受到发展空间狭小、城镇建设用地紧缺的限制。因此,削山造地,开挖坡脚等现象势必诱发大量的地质灾害(张茂省等,2019a,2019b)(图2)。
西安地质调查中心于2021年完成略阳县1∶50 000地质灾害调查评价及重点区域1∶10000调查评价等工作,研究区内完成滑坡点调查137处(图1),主要分布于剥蚀中山和剥蚀低山区,其中剥蚀低山区有91处滑坡,占总数的66.5%;剥蚀中山区有46处滑坡,占总数的33.5%。滑坡以中小型为主,其中大型滑坡14处,占比为10.22%;中型滑坡69处,占比为50.36%;小型滑坡54处,占比为39.42%,滑坡灾害具有线性分布特点,主要沿嘉陵江、宝成铁路和309省道康勉公路略阳段两侧分布。
1.2 研究方法
1.2.1 深度随机森林算法
深度随机森林算法采用Bagging集成学习方法,对树构成的森林进行集成串联,通过分类器进行特征学习,从而充分利用深度特征提取来提高分类效果。其网络模型结构主要包括多粒度扫描模块(图3a)和级联森林模块(图3b)。
图 3 深度随机森林模型流程结构(据Zhou, 2017)Figure 3. Process structure illustration of Deep Random Forest Model(1)多粒度扫描模块
设滑坡影响因子数目为n(称为n维),滑动窗口数目为m(称为m维),把滑坡影响因子的n维数据划分为(n−m+1)个数据实例,将它们输入到2个随机森林进行训练,生成k个(k为滑坡易发性等级数目,文中设置4个易发性等级)概率向量,合并结果,获得(n−m+1)×k维概率向量。
(2)级联森林模块
首先将通过粒度扫描模块得到的概率向量输入,在2个随机森林(图3b中的黑色部分)和2个完全随机森林(图3b中的蓝色部分)进行训练。随机森林和完全随机森林使用基尼指数(Gini index,简称Gini)进行树的节点分裂,其公式为:
$$ {G}{i}{n}{i}\left({D}\right)=1-\sum _{{i}}^{{k}}{{p}}_{{i}}^{2} $$ (1) 式中:D是空间数据库的样本数据集,pi是该样本集中记录属于ki(表示极高易发、高易发、中易发、低易发和极低易发)种类的概率,并用
$|k_{i, D}| /|D|$ 进行计算。$$ {{G}{i}{n}{i}}_{{A}}\left({D}\right)=\frac{{︱}{{D}}_{1}{︱}}{{︱}{D}{︱}}{G}{i}{n}{i}\left({{D}}_{1}\right)+\frac{{︱}{{D}}_{2}{︱}}{{︱}{D}{︱}}{G}{i}{n}{i}\left({{D}}_{2}\right) $$ (2) 式中:A是空间数据库中滑坡影响因子属性,按照滑坡影响因子属性A将样本集进一步分为D1、D2。对于离散属性A,选择该属性最小基尼指数的子集作为它的分裂指数。
每个森林生成一个k维的概率向量与原始的概率向量[2×(n−m+1)×k]合并作为下一级联层的输入并采用K折交叉验证方法进行训练,避免出现过拟合。其计算公式如下:
$$ {\beta }=\frac{\displaystyle \sum _{{i}=1}^{{n}}{{Q}}_{{i}}}{{p}} $$ (3) 式中:p为数据集划分子集的个数,Qi为第i次划分的结果。在训练过程中级联层依次迭代,直到分类精度相较于未扩展前(称最大级联层数)没有显著提高,训练过程终止,从而构建基于深度森林的滑坡易发性评价模型。
1.2.2 数据来源
笔者所采用的滑坡详细调查数据来源于秦岭南部地区灾害地质调查项目2020年开展的略阳县幅1∶50 000及1∶10 000地质灾害调查成果。针对该区域进行易发性评价所采用的基础数据来源于陕西省测绘局(包括1∶50 000和1∶10 000地形图及DEM数据),用于提取高程、坡度、相对高差、坡向、坡型、水系、公路铁路等信息;地层岩性及断裂分布等图件来源于中国地质调查局西安地质调查中心,植被归一化指数的数据来源于中国科学院资源环境科学数据中心。
2. 评价因子选取及分级
2.1 评价因子选取
滑坡受多种因素影响,在野外调查及滑坡灾害信息编录的基础上,依据地质灾害形成的控制因素、影响因素、诱发因素、变形迹象、已有地质灾害等5大类多源数据,主要利用已有地质灾害发生前和发生后对比数据,设计建立训练数据集(张茂省等,2019a,2019b),结合研究区地质环境条件,调研前人对与研究区类似的地质条件进行滑坡发生机理及影响因素的相关文献(张春山等,2008;张永双等,2011;孟庆华,2011;邱海军,2012;王涛等,2013;周样样,2013;周静静等,2019;吴常润等,2020),选取9类评价因子,分别为坡度、相对高差、坡向、坡型、工程地质岩组、断裂距离、河流水系距离、公路铁路距离、植被归一化指数等。各因子的等级划分见图4。
2.2 评价因子分级
基于选择的9类评价因子及分区进行信息量计算,结合研究区总面积(S)为165.68km2,滑坡点总数(N)为137个,得到各评价因子分区面积(Si)、各评价因子灾害点数(Ni)及各评价因子(Ii)等(表1)。
表 1 各评价因子信息量表Table 1. Weighted information values of individual evaluation factors因子 分级 Si(km2) Ni(个) Ii 坡度 <10° 10.535625 8 −0.085244 10°~20° 13.3961 21 0.639636 20°~30° 35.77955 46 0.441342 30°~40° 54.226925 38 −0.165514 40°~50° 38.6219 12 −0.978836 >50° 13.119575 12 0.100879 相对高差 16~175 m 24.930925 53 0.944260 175~238 m 55.38815 46 0.004353 238~300 m 49.224425 29 −0.339017 300~379 m 26.43665 8 −1.005232 379~605 m 9.6986 1 −2.081904 坡向 0~45° 23.746850 21 0.067150 45°~90° 21.137625 23 0.274517 90°~135° 17.924900 10 −0.393528 135°~180° 18.869250 14 −0.108399 180°~225° 20.641625 26 0.420864 225°~275° 22.018400 18 −0.011429 275°~315° 20.152475 13 −0.248300 315°~360° 21.185550 12 −0.378335 曲率 <−0.5(凹形坡) 11.1099 12 0.267147 −0.5~0.5
(直线形坡)143.597 119 0.002190 >0.5(凸形坡) 10.969775 6 −0.413307 工程地质岩组 坚硬岩组 65.882425 40 −0.308915 半坚硬岩组 29.980725 13 −0.645528 软硬相间岩组 58.766425 46 −0.054852 松散岩组 11.050425 39 1.451170 距断裂距离 <100 m 31.79 26 −0.010915 100~200 m 25.87 26 0.195167 200~500 m 49.79 53 0.252595 500~1000 m 34.60 23 −0.218224 >1000 m 23.64 9 −0.775554 距河流水系
距离<200 m 69.69 86 0.400425 200~400 m 52.38 31 −0.334384 400~600 m 27.98 17 −0.308056 600~800 m 11.37 1 −2.240549 >800 m 4.28 2 −0.569794 距公路、铁路
距离<100 m 18.99 58 1.306584 100~500 m 46.12 41 0.072488 500~1000 m 38.06 14 −0.809915 1000~1500 m 26.29 11 −0.681226 >1500 m 36.23 13 −0.834794 NDVI −0.41~0.07 1.88 0 0.07~0.32 7.64 26 1.415100 0.32~0.52 26.25 56 0.947905 0.52~0.68 91.74 50 −0.416840 0.68~0.84 38.18 5 −1.842838 统计结果显示(表1),在坡度评价因子中,10°~40°区间为滑坡多发区,滑坡数量为105处,占全部滑坡的76.64%;在相对高差评价因子中,高差300 m以内为滑坡多发区,滑坡数量为128处,占全部滑坡的93.43%;在坡向评价因子中,滑坡分布较为平均;在曲率评价因子中,直线型坡滑坡为119处,占全部滑坡的86.86%;在工程地质岩组评价因子中,坚硬岩组、软硬相间岩组、松散岩组发生的滑坡为125处,占全部滑坡的91.24%,这里值得一提的是,坚硬岩组发生40处滑坡,主要是由于表层堆积层滑坡沿节理或基覆界面所发生;在断裂距离评价因子中,距离1000 m以内发生滑坡共128处,占全部滑坡的93.43%;在水系距离评价因子中,距离400 m以内发生滑坡共117处,占全部滑坡的85.40%;在公路铁路距离评价因子中,距离1000 m以内发生滑坡共113处,占全部滑坡的82.48%;在NDVI植被归一化指数中,<0.68为发生滑坡的主要区域,共发生滑坡132处,占全部滑坡的96.35%。
3. 滑坡易发性评价
笔者将研究区栅格文件按照5m × 5m进行划分,共分割成6627144个栅格。每个栅格看作一个点,分别从研究区的9个评价因子中提取数据。样本数据中滑坡与非滑坡的比例将影响模型的特征学习,一个平衡的比例使模型精确度达到最优值。笔者获取137处滑坡点为滑坡样本数据集,依据研究人员的经验,选取142处非滑坡点作为非滑坡样本数据集,随后随机从137处滑坡点和142处非滑坡点构成的样本集中抽取70%作为训练样本集,30%作为测试样本集。为避免非滑坡区样本选取时易将潜在滑坡视为非滑坡而造成的误差(刘坚等,2018),通过对各因子分级的信息量数据进行分析,人工从低易发区选取非易发点。在这过程当中,提取所有栅格单元的评价因子值并进行归一化处理。
通过Arcpy接口,传输ArcGIS各单因子评价数据于Python语言环境内并使其实现核完成随机森林算法和深度随机森林算法预测,再将算法结果数据从Python语言环境中传输回ArcGis10.5软件进行易发性评价。在地质灾害相关评价中,针对栅格赋值并归一化后的离散数据常用的分区方法有自然断点法(邱维蓉等,2020)、基于数理统计的自然拐点法(王佳运等,2020)、百分位数法(吴孝情等,2017)、相等间隔法(田春山等,2016)等。在空间统计分析中,自然断点法以自然(或非人为设定)的转折点和断点为分区界线,实现将研究对象分成性质相似的群组,实现每一组内部数据的相似性最大。基于数理统计的自然拐点法其思想和自然断点法类似,都是寻找数值中间的自然转折点,但该方法在针对归一化的海量数据求导后,存在拐点阈值难以界定的问题,虽然可以通过Matlab或Pyhton的帮助而找到拐点,但这个过程是将求导后的数据结果进行曲线拟合而完成,在拟合过程中存在一定的数据偏离。百分位数法和相等间隔法是通过人为确定数值的间隔来完成分区,掺杂一定的主观性,难以客观体现出不同区域边坡的易发性。因此,笔者选择自然断点法来完成易发性分区(图5、图6),通过栅格统计工具,完成易发性评价等级的相关统计分析。
通过上述步骤分别得到随机森林易发性评价图(图5)和深度随机森林易发性评价图(图6),按自然资源部中国地质调查局地质调查技术标准(DD 2019–08)——地质灾害调查技术要求(1∶50 000),将研究区分为极高易发区、高易发区、中易发区及低易发区。
据ArcGIS分区统计显示,随机森林易发性评价图内,极高易发区的面积为5.32 km2,占比为3.21%,发生滑坡数量为22个;高易发区面积为18.63 km2,占比为11.24%,发生滑坡数量为40个;中易发区面积为114.65 km2,占比为69.20%,发生滑坡数量为74个;低易发区面积为27.08 km2,占比为16.34%,发生滑坡数量为1个。
深度随机森林易发性评价图内,极高易发区面积为8.8 km2,占比为5.31%,发生滑坡数量为27个;高易发区面积为38.05 km2,占比为22.97%,发生滑坡数量为62个;中易发区面积为69.77 km2,占比为42.11%,发生滑坡数量为41个;低易发区面积为49.06 km2,占比为29.61%,发生滑坡数量为7个。
将随机森林和深度随机森林法所得到的易发性分区结果与滑坡分布的实际情况做对比(表2),是一种常用的对评价结果初步检验(薛强,2015)。随易发性等级的提高,各等级中所包含的滑坡数量同步递增,同时滑坡实际发生的比率(c/a)也在增大,说明这2种方法所得出的易发等级与滑坡发生的实际情况基本吻合,划分结果较为理想。
表 2 易发性等级划分与滑坡实际发生比率对比表Table 2. Comparison of susceptibility classification and actual landslide occurrence rate评价
方法易发性
等级a
易发分区面积占比(%)b
分区滑坡数量c
滑坡百分比(%)c/a
滑坡发生比率随机森林 低 16.34 1 0.73 0.04 中 69.21 74 54.01 0.78 高 11.24 40 29.20 2.60 极高 3.21 22 16.06 5.00 深度
随机森林低 29.61 7 5.11 0.17 中 42.11 41 29.93 0.71 高 22.97 62 45.26 1.97 极高 5.31 27 19.71 3.71 极高易发区和高易发区主要分布于中低山区与河谷接壤地带,地层由松散岩组的坡积层碎石土和软硬相间岩组如片岩、千枚岩、板岩等构成,工程地质条件属于强度较低,稳定性较差。其中坡积层较为松散,利于地表水入渗,下伏基岩又起到阻水作用。因此,在该层中储存的孔隙水易导致坡体失稳、破坏而形成滑动或滑塌。软硬相间的岩组更多受强烈活动的断裂和多期褶皱的影响,造成地表破碎,节理裂隙发育,为孕灾提供了物质基础。加上人类工程活动在河谷两岸,削坡修建四通八达的公路网、铁路及房屋,特别是嘉陵江两岸、宝成铁路与省道公路沿线均容易由于边坡失稳而导致滑坡形成。
4. 评价结果验证分析
不论是随机森林法还是深度随机森林法,所得到的易发性分区结果都基本与研究区的地貌、构造、工程地质岩组、人类活动等有着强烈的联系,它们的滑坡分布趋势是相一致的。在此引进一个衡量易发性分区评价的检验指标,来对这2种方法的优劣性进行分析。
在地质灾害易发性评价中,前人常使用ROC(Receiver Operating Characteristic Curve)曲线对分区结果进行验证,通过计算AUC(Area Under Curve)值来评价区划结果的准确性(Chung et al.,2003;孟晓捷等,2022)。笔者在采用ROC曲线进行对比时,y轴表示把实际为真值(滑坡)的预测为真值(滑坡)的概率;x轴表示把实际为假值(非滑坡)的预测为真值(滑坡)的概率,采用构图法描绘危险性和特异性的相互关系。随后得到ROC曲线内的面积,即AUC值。当AUC≤0.5,表明评价模型的预测能力无效;当0.5<AUC≤0.7,表明评价模型的预测能力具有一定的准确性;当0.7<AUC≤0.9,表明评价模型的预测能力具有较好的准确性;当AUC≥0.9,表明评价模型的预测能力较高。
在模型验证过程中,按照上节的训练集与测试集的比例,从样本集中随机抽5组训练集与测试集;接着依据5组测试集中真实值与预测值,计算每组RF与DRF的AUC值,求这5组的平均值,即获得RF和DRF的AUC值分别为86.3%和91.2%,从而绘制ROC曲线(图7)。
基于随机森林和深度随机森林的滑坡预测模型的AUC值都高于0.7,说明这2个模型的预测能力具有一定的准确性。深度随机森林评价模型的AUC值比随机森林高出4.9%,因此深度随机森林的模型预测精确度略高于随机森林模型。其产生的原因是:虽然随机森林和深度随机森林都采用集成学习方法,但是随机森林只是同时训练多个决策树,使用类似投票方式获取最终结果来提高预测精确度;而深度随机森林通过多粒度扫描技术,其特征学习能力得到进一步的提升。另外深度随机森林采用K折交叉验证方法避免过拟合,从而提高了滑坡危险性评价易发性评价模型的精确度。
5. 结论
(1)笔者以秦岭山区腹地汉中市略阳县城主区域为研究对象,在1∶5万及1∶1万调查基础上,选取坡度、相对高差、坡向、坡型、工程地质岩组、断裂距离、河流水系距离、公路铁路距离及NDVI植被归一化指数等9个要素作为易发性评价指标。基于ArcGIS平台和随机森林及深度随机森林的融合,将评价结果进一步分为极高易发区、高易发区、中易发区和低易发区。经ROC曲线验证,深度随机森林评价模型预测精度达到91.2%。其评价结果具有一定的可行性及科学合理性。
(2)研究区内滑坡点共有137处,主要分布于剥蚀中山、低山区。剥蚀低山区有91处滑坡,占总数的66.5%;剥蚀中山区有46处滑坡,占总数的33.5%。滑坡以中小型为主,其中大型滑坡14处,占比为10.22 %;中型滑坡69处,占比为50.36%;小型滑坡54处,占比为39.42%。极高易发区、高易发区主要分布于嘉陵江两岸、宝成铁路与省道公路沿线,地貌类型为秦岭中低山区,工程地质岩组主要为松散岩组及软硬相间岩组,距断裂500 m以内,距河流水系400 m以内,距公路铁路等工程活动500 m以内的地区。
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图 1 秦岭造山带地质简图(据Dong et al.,2011a修改)
LLWF.灵宝–鲁山–舞阳断裂;LLF.洛南–栾川断裂;N–SCB.华南板块北缘;1.华北板块南缘;2.宽坪岩群;3.秦岭杂岩;4.商丹缝合带;5.二郎坪群;6.南秦岭南部带;7.南秦岭北部带;8.MLSZ.勉略缝合带;9.大别地体
Figure 1. Simplified tectonic division of the Qinling orogenic belt
图 2 涝峪地区地质图及采样位置(据陕西省地质局区测队,1966;陕西地质局13队,1972修改)
Figure 2. Simplified geological map of Laoyu area, showing the with sample location
图 4 二云母石英片岩和含石榴子石二云母石英片岩显微照片
a.二云母石英片岩样品KP-3片理发生褶皱弯曲(单偏光);b.二云母石英片岩样品KP-3部分区域TIMA扫描图显示褶皱变形;c.二云母石英片岩样品KP-3中的黑云母、白云母、石英和钠长石等矿物(正交偏光);d.二云母石英片岩样品KP-4中黑云母、白云母和石英等矿物(单偏光);e.二云母石英片岩样品KP-4中黑云母、白云母和石英等矿物以及明显的片理构造(正交偏光);f.二云母石英片岩样品KP-4部分区域TIMA扫描图;g、h.含石榴子石二云母石英片岩样品KP2202石榴子石变斑晶和基质矿物黑云母,白云母,斜长石,和石英(单偏光);i.含石榴子石二云母石英片岩样品KP2202中黑云母、白云母、石英、斜长石和钛铁矿等矿物(背散射照片)
Figure 4. Photomicrographs of the two-mica quartz schist and the garnet-berting two-mica quartz schist
图 14 宽坪岩群变质温压条件及P–T轨迹
轨迹1和2分别为桐柏地区宽坪岩群北部和南部构造单元变质P–T轨迹(Liu et al., 2011);轨迹3为红土岭地区含石榴子石石英片岩变质P–T轨迹(王海杰等,2021);区域4和5分别为涝峪地区宽坪岩群中二云母石英片岩和含石榴子石二云母石英片岩变质温压条件(本研究)
Figure 14. Summary of metamorphic P–T conditions and paths for the Kuanping Group
表 1 二云母石英片岩样品KP-3和KP-4中黑云母和白云母成分
Table 1 Mineral composition of biotite and muscovite in the two-mica quartz schist of sample KP-3 and KP-4
样品
矿物KP-3 Bt Ms SiO2 36.86 38.09 37.80 37.83 37.22 37.78 37.82 37.52 52.08 49.36 51.96 50.57 48.34 47.86 48.25 47.59 TiO2 1.02 0.96 1.11 0.89 0.83 1.11 0.97 1.13 0.12 0.11 0.19 0.19 0.12 0.11 0.12 0.20 Al2O3 18.09 18.02 17.74 16.90 17.33 17.52 17.45 17.36 27.74 29.36 28.04 29.78 33.02 33.08 32.75 32.79 FeO 20.10 19.12 19.74 19.25 20.17 19.42 20.42 20.14 2.39 2.13 2.56 2.29 2.16 1.98 2.12 2.22 MnO 0.18 0.14 0.16 0.04 0.00 0.09 0.12 0.09 0.00 0.04 0.01 0.04 0.00 0.01 0.02 0.05 MgO 8.79 9.19 9.24 9.53 9.49 9.62 9.22 9.74 2.84 2.40 2.74 2.36 1.31 1.29 1.36 1.23 CaO 0.01 0.00 0.11 0.03 0.02 0.04 0.00 0.04 0.00 0.02 0.01 0.01 0.00 0.00 0.00 0.00 Na2O 0.06 0.07 0.03 0.05 0.08 0.05 0.04 0.09 0.16 0.20 0.18 0.22 0.33 0.41 0.48 0.35 K2O 8.85 9.03 8.21 8.81 8.96 8.80 9.23 8.52 10.33 10.20 10.34 10.52 10.52 10.75 10.53 10.72 Totals 93.96 94.61 94.15 93.34 94.09 94.42 95.27 94.63 95.66 94.94 96.03 95.98 95.80 95.49 95.63 95.14 Oxygens 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 Si 2.84 2.89 2.88 2.91 2.86 2.88 2.87 2.86 3.44 3.31 3.43 3.34 3.20 3.19 3.21 3.19 Ti 0.06 0.06 0.06 0.05 0.05 0.06 0.06 0.07 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Al 1.64 1.61 1.59 1.53 1.57 1.57 1.56 1.56 2.16 2.32 2.18 2.32 2.58 2.60 2.57 2.59 Fe3+ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.06 0.00 0.00 0.00 0.00 0.00 0.00 Fe2+ 1.29 1.21 1.26 1.24 1.30 1.24 1.30 1.28 0.13 0.12 0.14 0.13 0.12 0.11 0.12 0.12 Mn 0.01 0.01 0.01 0.00 0.00 0.01 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mg 1.01 1.04 1.05 1.09 1.09 1.09 1.04 1.11 0.28 0.24 0.27 0.23 0.13 0.13 0.14 0.12 Ca 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Na 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.03 0.02 0.03 0.04 0.05 0.06 0.05 K 0.87 0.87 0.80 0.87 0.88 0.85 0.89 0.83 0.87 0.87 0.87 0.89 0.89 0.91 0.89 0.92 Sum 7.73 7.70 7.66 7.71 7.75 7.71 7.74 7.72 6.92 6.95 6.92 6.95 6.97 6.99 6.98 6.99 Mg# 0.44 0.46 0.45 0.47 0.46 0.47 0.45 0.46 0.68 0.67 0.66 0.65 0.52 0.54 0.53 0.50 AlⅥ 0.47 0.50 0.47 0.44 0.43 0.45 0.44 0.42 1.67 1.61 1.66 1.78 1.78 1.77 1.77 1.55 XTi 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 XFe 0.46 0.43 0.44 0.44 0.45 0.44 0.46 0.45 0.07 0.06 0.07 0.06 0.06 0.05 0.06 0.06 XMg 0.36 0.37 0.37 0.39 0.38 0.38 0.37 0.39 0.14 0.12 0.13 0.11 0.06 0.06 0.07 0.06 T(℃)① 428 405 461 385 333 463 405 468 - - - - - - - - T(℃)② 491 482 495 464 455 488 476 485 - - - - - - - - 续表1 样品
矿物KP-4 Bt Ms SiO2 39.47 39.17 38.65 38.87 37.79 37.96 37.32 37.30 49.08 49.20 51.91 50.22 48.64 49.35 48.80 48.45 TiO2 0.83 0.83 0.93 0.76 0.84 0.79 0.98 0.96 0.23 0.09 0.20 0.09 0.05 0.23 0.11 0.05 Al2O3 17.77 18.12 17.97 18.22 18.05 17.53 17.42 17.19 34.04 35.13 30.48 33.82 33.17 32.12 32.23 32.49 FeO 16.53 16.74 16.65 16.10 17.53 17.59 18.11 17.90 0.64 0.57 1.09 0.57 1.92 2.37 1.89 2.01 MnO 0.04 0.12 0.11 0.11 0.13 0.07 0.07 0.14 0.00 0.01 0.00 0.15 0.00 0.03 0.00 0.00 MgO 10.91 11.11 10.94 10.96 10.53 10.48 10.70 10.86 1.57 1.46 2.53 1.81 1.51 1.77 1.71 1.43 CaO 0.14 0.12 0.11 0.12 0.03 0.05 0.09 0.05 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 Na2O 0.04 0.05 0.01 0.09 0.09 0.09 0.03 0.01 0.35 0.37 0.10 0.26 0.31 0.32 0.32 0.28 K2O 7.97 8.14 8.00 8.20 8.99 8.92 8.49 8.61 9.68 9.82 9.31 9.71 10.59 10.74 10.61 10.76 Totals 93.71 94.38 93.35 93.41 93.97 93.49 93.21 93.02 97.03 98.12 96.68 98.09 96.18 96.92 95.67 95.47 Oxygens 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 Si 2.95 2.92 2.91 2.92 2.87 2.89 2.86 2.86 3.18 3.15 3.36 3.22 3.21 3.24 3.24 3.22 Ti 0.05 0.05 0.05 0.04 0.05 0.05 0.06 0.06 0.01 0.00 0.01 0.00 0.00 0.01 0.01 0.00 Al 1.57 1.59 1.60 1.61 1.61 1.58 1.57 1.56 2.60 2.66 2.33 2.55 2.58 2.49 2.52 2.55 Fe3+ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.07 0.07 0.05 0.07 0.00 0.00 0.00 0.00 Fe2+ 1.04 1.04 1.05 1.01 1.11 1.12 1.16 1.15 0.04 0.03 0.06 0.03 0.11 0.13 0.10 0.11 Mn 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 Mg 1.22 1.23 1.23 1.23 1.19 1.19 1.22 1.24 0.15 0.14 0.24 0.17 0.15 0.17 0.17 0.14 Ca 0.01 0.01 0.01 0.01 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Na 0.01 0.01 0.00 0.01 0.01 0.01 0.00 0.00 0.04 0.05 0.01 0.03 0.04 0.04 0.04 0.04 K 0.76 0.77 0.77 0.79 0.87 0.87 0.83 0.84 0.80 0.80 0.77 0.79 0.89 0.90 0.90 0.91 Sum 7.60 7.63 7.62 7.63 7.72 7.72 7.72 7.73 6.89 6.90 6.83 6.88 6.97 6.98 6.97 6.98 Mg# 0.54 0.54 0.54 0.55 0.52 0.51 0.51 0.52 0.81 0.82 0.81 0.85 0.58 0.57 0.62 0.56 AlⅥ 0.52 0.51 0.51 0.53 0.48 0.47 0.43 0.42 1.84 1.87 1.73 1.82 1.78 1.72 1.75 1.77 X(Ti) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.00 0.00 0.00 0.00 0.01 0.00 0.00 X(Fe) 0.37 0.37 0.37 0.36 0.39 0.40 0.40 0.40 0.02 0.02 0.03 0.02 0.05 0.06 0.05 0.06 X(Mg) 0.43 0.44 0.43 0.44 0.42 0.42 0.43 0.43 0.08 0.07 0.12 0.09 0.07 0.09 0.08 0.07 T(℃)① 381 382 433 341 378 346 442 440 - - - - - - - - T(℃)② 455 452 465 447 454 446 463 458 - - - - - - - - 注:Mg#=Mg/(Mg+Fe2+),XTi=Ti/(Ti+Fe2++Mg+AlVI),XFe=Fe/(Ti+Fe2++Mg+AlVI),XMg=Mg/(Ti+Fe2++Mg+AlVI);①为Henry等(2005)计算的黑云母Ti温度计结果;②为Wu等(2015)计算的黑云母Ti温度计结果。 表 2 含石榴子石二云母石英片岩样品KP2202中黑云母、白云母、斜长石和石榴子石成分
Table 2 Mineral compositions of biotite, muscovite, plagioclase and garnet in the garnet-bearing two-mica quartz schist sample KP2202
样品 KP2202 位置 接触 基质 矿物 Bt Bt SiO2 34.34 33.63 34.90 34.56 34.02 34.09 34.27 35.23 34.54 34.79 33.95 34.59 34.34 34.55 34.55 34.41 TiO2 2.82 2.87 3.08 3.23 3.13 3.08 3.21 2.95 3.06 3.30 3.15 3.37 3.42 3.39 3.08 3.30 Al2O3 17.78 18.10 18.31 18.33 17.94 18.11 17.61 18.47 18.73 17.94 17.86 18.26 18.42 18.32 18.68 18.09 Cr2O3 0.08 0.08 0.03 0.05 0.03 0.07 0.12 0.05 0.03 0.01 0.01 0.02 0.02 0.10 0.02 0.00 FeO 23.43 22.76 23.32 23.57 23.76 23.44 22.97 22.73 22.26 21.81 21.73 22.11 22.36 22.02 21.00 22.34 MnO 0.43 0.32 0.53 0.54 0.48 0.52 0.39 0.31 0.29 0.29 0.27 0.24 0.25 0.24 0.19 0.30 MgO 5.51 6.19 5.30 5.15 4.95 5.73 5.78 6.22 5.99 6.17 6.17 6.23 6.08 6.34 6.58 6.36 CaO 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Na2O 0.14 0.13 0.14 0.12 0.10 0.09 0.06 0.13 0.17 0.12 0.08 0.05 0.10 0.17 0.10 0.08 K2O 10.01 9.41 10.12 9.99 9.90 9.99 9.91 10.22 10.27 9.99 10.35 9.75 10.21 9.91 10.01 10.00 SrO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 NiO 0.01 0.00 0.01 0.02 0.00 0.05 0.04 0.00 0.01 0.00 0.01 0.04 0.03 0.07 0.00 0.03 Totals 94.56 93.49 95.75 95.56 94.31 95.16 94.34 96.30 95.36 94.42 93.59 94.66 95.23 95.11 94.22 94.91 Oxygens 11.00 11.00 11.00 11.00 11.00 11.00 11.00 11.00 11.00 11.00 11.00 11.00 11.00 11.00 11.00 11.00 Si 2.71 2.67 2.72 2.70 2.70 2.68 2.71 2.71 2.69 2.73 2.70 2.70 2.68 2.69 2.70 2.69 Ti 0.17 0.17 0.18 0.19 0.19 0.18 0.19 0.17 0.18 0.19 0.19 0.20 0.20 0.20 0.18 0.19 Al 1.66 1.70 1.68 1.69 1.68 1.68 1.64 1.68 1.72 1.66 1.67 1.68 1.69 1.68 1.72 1.67 Cr 0.01 0.01 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 Fe3+ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Fe2+ 1.55 1.51 1.52 1.54 1.58 1.54 1.52 1.46 1.45 1.43 1.44 1.45 1.46 1.43 1.37 1.46 Mn 0.03 0.02 0.04 0.04 0.03 0.04 0.03 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.02 Mg 0.65 0.73 0.62 0.60 0.59 0.67 0.68 0.71 0.70 0.72 0.73 0.73 0.71 0.74 0.77 0.74 Ca 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Na 0.02 0.02 0.02 0.02 0.02 0.01 0.01 0.02 0.03 0.02 0.01 0.01 0.02 0.03 0.02 0.01 K 1.01 0.96 1.01 1.00 1.00 1.00 1.00 1.00 1.02 1.00 1.05 0.97 1.02 0.98 1.00 1.00 Sum 7.80 7.79 7.78 7.77 7.78 7.81 7.78 7.79 7.80 7.76 7.81 7.75 7.79 7.77 7.77 7.79 Mg# 0.30 0.33 0.29 0.28 0.27 0.30 0.31 0.33 0.32 0.34 0.34 0.33 0.33 0.34 0.36 0.34 T(℃) 651.93 658.34 662.65 670.67 667.59 665.50 673.55 657.52 664.55 678.05 673.30 681.07 682.69 682.28 669.56 678.18 XAn - - - - - - - - - - - - - - - - XAb - - - - - - - - - - - - - - - - XOr - - - - - - - - - - - - - - - - XAlm - - - - - - - - - - - - - - - - XSps - - - - - - - - - - - - - - - - Xpy - - - - - - - - - - - - - - - - XGrs - - - - - - - - - - - - - - - - 续表2 样品 KP2202 位置 - 边部 核部 矿物 Ms Pl Grt Grt SiO2 45.44 45.36 45.60 45.33 45.76 45.74 61.80 62.30 61.47 36.66 36.54 37.05 36.37 36.23 36.94 36.56 TiO2 1.09 1.14 0.62 0.71 0.62 0.65 0.00 0.05 0.02 0.06 0.08 0.10 0.06 0.03 0.00 0.08 Al2O3 35.01 34.91 35.29 35.11 35.43 34.84 24.06 23.28 24.25 20.64 21.19 21.14 21.02 20.84 20.98 20.83 Cr2O3 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.03 0.00 0.02 0.00 0.04 0.00 0.00 0.00 0.00 FeO 1.50 1.52 1.68 1.67 1.54 1.65 0.15 0.18 0.08 29.03 28.37 30.50 33.61 33.81 33.93 33.70 MnO 0.00 0.01 0.09 0.02 0.06 0.01 0.00 0.00 0.04 8.10 6.34 5.91 5.62 5.64 5.58 5.37 MgO 0.54 0.60 0.57 0.54 0.52 0.62 0.00 0.01 0.01 1.36 1.25 1.36 1.51 1.55 1.61 1.63 CaO 0.02 0.00 0.06 0.00 0.08 0.00 5.94 5.71 6.28 3.45 5.26 3.41 1.27 1.05 1.02 0.97 Na2O 0.36 0.40 0.50 0.34 0.40 0.33 8.33 8.48 8.36 0.00 0.00 0.00 0.01 0.03 0.02 0.02 K2O 11.28 11.44 11.12 10.89 11.26 11.03 0.19 0.18 0.22 0.00 0.02 0.00 0.00 0.00 0.00 0.03 SrO 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.16 0.09 0.00 0.00 0.00 0.00 0.00 0.00 0.00 NiO 0.00 0.02 0.04 0.01 0.00 0.02 0.00 0.03 0.01 0.01 0.00 0.00 0.01 0.00 0.02 0.02 Totals 95.24 95.39 95.57 94.63 95.68 94.90 100.53 100.41 100.82 99.34 99.04 99.51 99.48 99.19 100.09 99.22 Oxygens 11.00 11.00 11.00 11.00 11.00 11.00 8.00 8.00 8.00 12.00 12.00 12.00 12.00 12.00 12.00 12.00 Si 3.05 3.04 3.05 3.05 3.05 3.07 2.73 2.76 2.72 3.00 2.98 3.01 2.98 2.98 3.00 3.00 Ti 0.06 0.06 0.03 0.04 0.03 0.03 0.00 0.00 0.00 0.00 0.01 0.01 0.00 0.00 0.00 0.01 Al 2.77 2.76 2.78 2.79 2.79 2.76 1.25 1.22 1.26 1.99 2.04 2.02 2.03 2.02 2.01 2.01 Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Fe3+ 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.00 0.01 0.00 0.00 0.01 0.03 0.00 0.00 Fe2+ 0.08 0.09 0.09 0.09 0.09 0.09 0.00 0.00 0.00 1.97 1.93 2.07 2.29 2.29 2.31 2.31 Mn 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.56 0.44 0.41 0.39 0.39 0.38 0.37 Mg 0.05 0.06 0.06 0.05 0.05 0.06 0.00 0.00 0.00 0.17 0.15 0.16 0.18 0.19 0.20 0.20 Ca 0.00 0.00 0.00 0.00 0.01 0.00 0.28 0.27 0.30 0.30 0.46 0.30 0.11 0.09 0.09 0.09 Na 0.05 0.05 0.07 0.04 0.05 0.04 0.71 0.73 0.72 0.00 0.00 0.00 0.00 0.01 0.00 0.00 K 0.97 0.98 0.95 0.94 0.96 0.95 0.01 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Sum 7.02 7.04 7.04 7.01 7.03 7.01 5.00 5.00 5.01 8.00 8.00 7.98 8.00 8.00 7.99 7.99 Mg# 0.39 0.41 0.38 0.36 0.38 0.40 - - - - - - - - - - T(°C) - - - - - - - - - - - - - - - - XAn - - - - - - 0.28 0.27 0.29 - - - - - - - XAb - - - - - - 0.71 0.72 0.70 - - - - - - - XOr - - - - - - 0.01 0.01 0.01 - - - - - - - XAlm - - - - - - - - - 0.66 0.65 0.70 0.77 0.77 0.78 0.78 XSps - - - - - - - - - 0.19 0.15 0.14 0.13 0.13 0.13 0.13 Xpy - - - - - - - - - 0.06 0.05 0.06 0.06 0.06 0.07 0.07 XGrs - - - - - - - - - 0.10 0.15 0.10 0.04 0.03 0.03 0.03 注:Mg#=Mg/(Mg+Fe2+), XAn = Ca/(Ca+Na+K), XAb = Na/(Ca+Na+K), XOr = K/(Ca+Na+K); XAlm = Fe2+/(Fe2++ Mn + Mg + Ca), XSps = Mn/
(Fe2+ + Mn + Mg + Ca), XPy = Mg/(Fe2+ + Mn + Mg + Ca), XGrs = Ca/(Fe2+ + Mn + Mg + Ca)。表 3 糜棱岩化含金云母大理岩样品KP-1中金云母成分
Table 3 Mineral compositions of phlogopite in the mylonitizd phlogopite-bearing marble sample KP-1
样品 KP-1 矿物 Phl SiO2 42.92 43.62 43.77 43.51 42.62 43.51 42.03 43.87 43.86 44.71 43.33 41.89 42.29 43.08 TiO2 0.60 0.82 0.55 0.39 0.55 0.73 0.78 0.46 0.41 0.39 0.49 0.53 0.57 0.62 Al2O3 16.35 15.69 15.68 16.11 16.33 16.48 16.59 15.23 15.02 15.02 15.95 17.42 17.57 17.54 FeO 1.45 1.62 1.23 1.91 1.35 1.48 1.70 1.57 1.48 1.55 2.02 1.71 1.87 1.82 MnO 0.02 0.00 0.03 0.00 0.01 0.03 0.00 0.06 0.00 0.00 0.00 0.00 0.00 0.00 MgO 22.49 22.69 22.96 22.92 22.37 22.06 22.36 23.16 22.77 23.38 22.63 22.06 21.88 21.84 CaO 0.02 0.02 0.05 0.02 0.06 0.04 0.00 0.11 0.05 0.02 0.02 0.08 0.07 0.09 Na2O 0.09 0.00 0.08 0.05 0.03 0.05 0.08 0.03 0.03 0.02 0.00 0.11 0.09 0.04 K2O 10.34 10.31 10.22 9.94 10.51 10.45 10.61 10.29 10.39 10.40 10.41 10.60 10.69 10.78 Totals 94.27 94.75 94.56 94.86 93.83 94.82 94.15 94.78 94.01 95.49 94.85 94.41 95.03 95.79 Oxygens 11 11 11 11 11 11 11 11 11 11 11 11 11 11 Si 3.01 3.04 3.05 3.02 3.00 3.03 2.96 3.06 3.08 3.09 3.02 2.94 2.95 2.98 Ti 0.03 0.04 0.03 0.02 0.03 0.04 0.04 0.02 0.02 0.02 0.03 0.03 0.03 0.03 Al 1.35 1.29 1.29 1.32 1.36 1.35 1.38 1.25 1.24 1.22 1.31 1.44 1.45 1.43 Fe3+ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Fe2+ 0.09 0.09 0.07 0.11 0.08 0.09 0.10 0.09 0.09 0.09 0.12 0.10 0.11 0.11 Mn 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Mg 2.35 2.36 2.38 2.37 2.35 2.29 2.35 2.40 2.38 2.41 2.35 2.31 2.28 2.25 Ca 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.01 0.00 0.00 0.00 0.01 0.01 0.01 Na 0.01 0.00 0.01 0.01 0.00 0.01 0.01 0.00 0.00 0.00 0.00 0.02 0.01 0.01 K 0.92 0.92 0.91 0.88 0.94 0.93 0.95 0.91 0.93 0.92 0.93 0.95 0.95 0.95 Sum 7.76 7.74 7.74 7.74 7.77 7.73 7.79 7.76 7.75 7.74 7.76 7.79 7.78 7.76 Mg# 0.97 0.96 0.97 0.96 0.97 0.96 0.96 0.96 0.96 0.96 0.95 0.96 0.95 0.96 注:Mg#=Mg/(Mg+Fe2+)。 表 4 用于变质相平衡模拟计算的全岩主量元素成分
Table 4 Whole-rock compositions used for phase equilibrium modelling
样品号 全岩成分 (%) SiO2 TiO2 Al2O3 Fe2O3 FeO MnO MgO CaO Na2O K2O P2O5 LOI Total KP-3 71.24 0.65 12.38 2.27 3.22 0.04 2.28 0.15 1.41 3.33 0.07 2.37 99.41 KP-4 79.14 0.52 9.34 1.78 1.88 0.03 1.84 0.11 0.11 2.76 0.05 2.22 99.78 KP2202 67.62 0.83 15.35 1.14 4.56 0.12 1.54 0.94 1.14 4.30 0.06 1.67 99.27 样品号 相平衡模拟中的各组分含量(mol%) SiO2 Al2O3 CaO MgO FeO K2O Na2O TiO2 O* KP-3 71.790 7.351 0.162 3.425 4.436 2.140 1.377 0.493 0.861 图9a、图9b KP-4 78.552 5.463 0.117 2.723 2.890 1.747 0.106 0.388 0.665 图10a、图10b KP2202 71.096 9.510 1.059 2.414 4.913 2.883 1.162 0.656 0.452 图11a、图11b 表 5 二云母石英片岩样品KP-3的原位LA–ICP–MS黑云母和白云母Rb–Sr同位素数据
Table 5 In-situ LA–ICP–MS biotite and muscovite Rb–Sr isotopic data for two-mica quartz schist sample KP-3
点位 87Rb/86Sr ±1σ 87Sr/86Sr ±1σ KP-3-1 18.0166 0.5389 0.7905 0.0054 KP-3-2 29.3416 0.7385 0.8532 0.006 KP-3-3 16.2009 0.2907 0.8181 0.0062 KP-3-4 11.5061 0.3663 0.7899 0.0087 KP-3-5 18.3369 0.634 0.7584 0.0045 KP-3-6 12.2389 0.2162 0.8048 0.0076 KP-3-7 9.3939 0.2595 0.7795 0.0064 KP-3-8 7.7139 0.1553 0.7546 0.0055 KP-3-9 21.9059 1.0708 0.792 0.0062 KP-3-10 25.4976 1.1164 0.8426 0.0173 KP-3-11 14.0422 0.6728 0.7924 0.0106 KP-3-12 5.4361 0.1816 0.7467 0.0082 KP-3-13 25.5866 1.2185 0.8107 0.0158 KP-3-14 13.3642 0.3398 0.7751 0.0106 KP-3-15 23.5856 0.3439 0.8086 0.0043 KP-3-16 22.733 0.6971 0.7778 0.0089 KP-3-17 9.3486 0.2784 0.7632 0.0067 KP-3-18 13.6249 0.4057 0.7588 0.0059 KP-3-19 14.5342 0.3112 0.804 0.0065 KP-3-20 8.2599 0.2115 0.7797 0.006 KP-3-21 12.2192 0.2215 0.8111 0.0043 KP-3-22 7.9982 0.1289 0.7937 0.0036 KP-3-23 12.193 0.2094 0.7927 0.0043 KP-3-24 19.7496 0.2937 0.795 0.005 KP-3-25 15.4003 0.207 0.7731 0.0056 KP-3-26 9.3778 0.2017 0.7779 0.0034 KP-3-27 24.297 1.0354 0.8161 0.0112 KP-3-28 12.085 0.3581 0.7911 0.0082 KP-3-29 33.6078 0.9551 0.8365 0.0091 KP-3-30 7.9611 0.246 0.7531 0.0046 KP-3-31 49.9564 4.4104 0.8407 0.0177 KP-3-32 4.1449 0.1021 0.7694 0.0053 KP-3-33 7.4286 0.1467 0.7646 0.0044 KP-3-34 20.7555 0.8895 0.8076 0.0073 KP-3-35 27.518 0.5935 0.8106 0.0049 KP-3-36 1.5058 0.1521 0.8035 0.0167 KP-3-37 1.2356 0.2309 0.8377 0.051 KP-3-38 0.2741 0.0215 0.7836 0.0107 KP-3-39 0.1349 0.0185 0.6885 0.0255 KP-3-40 0.3264 0.0426 0.7562 0.0312 表 6 二云母石英片岩样品KP-4原位LA–ICP–MS黑云母和白云母Rb–Sr同位素数据
Table 6 In-situ LA–ICP–MS biotite and muscovite Rb–Sr isotopic data for two-mica quartz schist sample KP-4
点位 87Rb/86Sr ±1σ 87Sr/86Sr ±1σ KP-4-1 25.4466 0.454 0.8146 0.01 KP-4-2 41.2259 0.8178 0.8114 0.0079 KP-4-3 50.6532 1.1725 0.7922 0.0087 KP-4-4 26.9311 0.438 0.8014 0.0064 KP-4-5 29.0531 0.6666 0.8158 0.0067 KP-4-8 33.0924 1.6649 0.7448 0.0052 KP-4-9 16.6476 0.937 0.7454 0.0037 KP-4-10 41.2109 0.9943 0.8229 0.0076 KP-4-11 52.4346 0.8291 0.8285 0.0066 KP-4-12 2.8604 0.0843 0.7251 0.0041 KP-4-15 26.8263 1.3235 0.8287 0.0105 KP-4-16 34.8779 2.2549 0.8122 0.0077 KP-4-17 17.2552 0.4462 0.7808 0.0089 KP-4-18 23.5465 0.563 0.8049 0.007 KP-4-19 50.8047 1.5759 0.8137 0.0101 KP-4-20 97.7716 2.5025 0.936 0.0087 KP-4-21 18.9715 0.5902 0.7807 0.0095 KP-4-22 41.6778 2.2637 0.8275 0.0074 KP-4-23 20.7999 1.0744 0.8215 0.0108 KP-4-25 41.9771 0.9381 0.7939 0.0067 KP-4-26 22.8923 0.7196 0.829 0.0054 KP-4-27 31.4178 1.6919 0.7813 0.0101 KP-4-28 75.0006 1.6558 0.9076 0.0148 KP-4-29 39.9303 0.4539 0.8809 0.0064 KP-4-30 32.9889 0.4273 0.8558 0.0057 KP-4-31 23.0713 0.4501 0.8065 0.007 KP-4-32 25.7233 0.2788 0.8232 0.0048 KP-4-33 22.6323 0.6414 0.7783 0.0051 KP-4-34 28.391 0.3844 0.8181 0.0062 KP-4-35 22.4479 0.319 0.814 0.0049 KP-4-36 2.8775 0.0568 0.7304 0.0022 KP-4-37 3.76 0.1344 0.7325 0.0032 KP-4-38 2.9363 0.067 0.7258 0.0018 KP-4-39 1.4073 0.0335 0.7136 0.0018 KP-4-40 1.6294 0.0683 0.7213 0.0016 表 7 含石榴子石二云母石英片岩样品KP2202原位LA–ICP–MS黑云母和白云母Rb–Sr同位素数据
Table 7 In-situ LA–ICP–MS biotite and muscovite Rb–Sr isotopic data for garnet-bearing two-mica quartz schist sample KP2202
点位 87Rb/86Sr ±1σ 87Sr/86Sr ±1σ 备注 KP2202-1 21.3446 0.3768 0.9061 0.0048 Ms type-1 KP2202-2 19.0802 0.3769 0.8668 0.0042 Ms type-1 KP2202-3 16.1607 0.2511 0.8231 0.0034 Ms type-1 KP2202-4 16.9611 0.2304 0.8289 0.0036 Ms type-1 KP2202-5 18.6972 0.2885 0.8846 0.0048 Ms type-1 KP2202-6 17.0929 0.2986 0.8348 0.0044 Ms type-1 KP2202-7 18.5684 0.3145 0.8665 0.0049 Ms type-1 KP2202-30 16.5679 0.2640 0.8370 0.0051 Ms type-1 KP2202-31 17.7241 0.3035 0.8377 0.0039 Ms type-1 KP2202-32 18.4186 0.3005 0.8608 0.0037 Ms type-1 KP2202-40 17.4755 0.2839 0.8292 0.0035 Ms type-1 KP2202-41 17.9974 0.4653 0.8317 0.0037 Ms type-1 KP2202-42 17.6600 0.2556 0.8307 0.0043 Ms type-1 KP2202-43 16.9642 0.2634 0.7930 0.0043 Ms type-1 KP2202-44 16.5281 0.2798 0.7920 0.0034 Ms type-1 KP2202-45 16.7014 0.3672 0.8173 0.0042 Ms type-1 KP2202-46 16.5453 0.3081 0.8112 0.0036 Ms type-1 KP2202-11 16.9159 0.2898 0.7945 0.0044 Ms type-2 KP2202-12 18.1469 0.3106 0.8010 0.0036 Ms type-2 KP2202-13 17.9112 0.3321 0.7941 0.0043 Ms type-2 KP2202-14 19.9469 0.3315 0.7963 0.0041 Ms type-2 KP2202-22 18.9035 0.3015 0.8021 0.0043 Ms type-2 KP2202-23 19.8987 0.3443 0.8003 0.0038 Ms type-2 KP2202-24 16.6555 0.3950 0.7835 0.0034 Ms type-2 KP2202-25 19.9471 0.3723 0.7958 0.0044 Ms type-2 KP2202-26 18.9892 0.3332 0.7960 0.0048 Ms type-2 KP2202-27 13.2982 0.4708 0.7900 0.0042 Ms type-2 KP2202-28 21.1990 0.5195 0.7927 0.0044 Ms type-2 KP2202-29 18.4951 0.4068 0.7961 0.0044 Ms type-2 KP2202-33 12.7696 1.1655 0.7887 0.0030 Ms type-2 KP2202-34 20.1844 0.5434 0.8058 0.0044 Ms type-2 KP2202-35 20.0061 0.3414 0.7961 0.0042 Ms type-2 KP2202-36 20.5787 0.3102 0.7904 0.0041 Ms type-2 KP2202-8 160.8024 8.5605 1.0268 0.0116 Bt KP2202-9 144.9303 10.2530 1.0157 0.0092 Bt KP2202-10 213.5181 8.7199 1.0947 0.0099 Bt KP2202-15 94.4528 9.3357 0.9103 0.0055 Bt KP2202-16 159.5003 4.9954 1.0145 0.0085 Bt KP2202-17 13.2294 1.5834 0.7817 0.0039 Bt KP2202-18 167.0161 7.1487 1.0332 0.0092 Bt KP2202-19 356.2216 22.0736 1.3801 0.0217 Bt KP2202-20 298.3693 22.7725 1.1905 0.0173 Bt KP2202-21 88.7981 7.0720 0.9202 0.0058 Bt KP2202-37 105.1556 9.6343 0.8970 0.0079 Bt KP2202-38 65.7936 2.7566 0.8580 0.0062 Bt KP2202-39 125.3506 3.5819 0.9300 0.0086 Bt KP2202-47 219.2769 13.2706 1.0912 0.0131 Bt KP2202-48 19.1462 1.1634 0.7931 0.0047 Bt KP2202-49 174.1023 10.2901 1.0229 0.0126 Bt KP2202-50 27.7117 1.1152 0.7805 0.0040 Bt -
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