本文主要研究内容
作者唐宗源(2019)在《大兴安岭中段中生代火山岩成因及地球动力学机制》一文中研究指出:大兴安岭地处中亚造山带东部,位于古亚洲洋构造域、蒙古-鄂霍茨克洋构造域和古太平洋构造域之间,经历了众多微陆块复杂的拼合历史和多次洋-陆转换过程,在微陆块闭合后的中生代时期又发生了大规模岩浆-成矿作用,从而成为我国独特的火山岩带。由于其特殊的地理位置,大兴安岭火山岩成因和地球动力学演化机制等一直以来作为地质学家的研究热点,然而这些问题仍有较大争论。大兴安岭中段的中生代火山岩地层出露相对完整,侵入岩也遍及各个时期,因此是研究大兴安岭中生代岩浆事件、岩石成因和其地球动力学机制的理想场所。本文通过大兴安岭中段中生代火山岩锆石LA-ICP-MS U-Pb年代学、全岩主量、微量元素和锆石Hf同位素的研究,在前人研究的基础上来探讨大兴安岭中段中生代火山作用期次、岩石成因和构造域对该区影响时限,另通过统计Hf-Nd同位素来揭示大兴安岭地区地壳增生的历史。大兴安岭中段中生代火山作用期次可分为三期:晚三叠世(235-225 Ma)、晚侏罗世-早白垩世(155-115 Ma),岩浆作用高峰出现在早白垩世中期(125 Ma)。晚侏罗世-早白垩世岩浆作用没有明显的间断期,应为火山喷发作用不同阶段的结果。大兴安岭中段中生代火山岩主要为哈达陶勒盖组、满克头鄂博组、玛尼吐组、白音高老组和梅勒图组地层。哈达陶勒盖组火山作用主要形成于晚三叠世(235-225Ma),并非前人认为的早三叠世;满克头鄂博组和玛尼吐组火山作用分别形成于155-140 Ma和150-125 Ma之间,满克头鄂博组和玛尼吐组火山岩喷发时限没有明显区分,但满克头鄂博组火山作用主体为晚侏罗世而玛尼吐组火山作用主体为早白垩世;白音高老组(135-120 Ma)和梅勒图组(130-120 Ma)火山作用主要形成于早白垩世。大兴安岭中段统计的大量晚侏罗世-早白垩世火山岩锆石U-Pb年龄显示,之前定义的同一个组的火山岩地层在不同地区的形成时代存在“穿时性”,以往仅根据地层组划分可能会造成火山岩形成时代的误判,本文认为以“时代+岩性”的表达方式更适合大兴安岭中生代火山岩。哈达陶勒盖组安山质-英安质火山岩具有较高的Sr含量、弱的Eu负异常和较低的Y以及Yb,部分具有较高的MgO含量,为“埃达克质岩石”。英安岩是通过同期安山质岩浆分离结晶形成的。地球化学特征显示出哈达陶勒盖组火山岩富集轻稀土元素和大离子亲石元素,亏损高场强元素的特征,并且具有正的εHf(t)值(+6.3至+12.7)和年轻的二阶段模式年龄(858-452 Ma),表明岩浆起源于新元古代-早古生代期间新增生的地壳物质的部分熔融。这些特征说明哈达陶勒盖组火山岩来自拆沉下地壳部分熔融,熔融的岩浆与地幔物质发生相互作用使埃达克质岩浆具有相对高MgO含量(Mg#值)。晚侏罗世-早白垩世安山质-英安质火山岩富集大离子亲石元素和轻稀土元素,并亏损高场强元素,显示弱或无Eu异常,具有正εHf(t)值(+6.2至+13.4)和Hf单阶段模型年龄(TDM1=556-270 Ma),岩浆来源于先前俯冲流体交代岩石圈地幔的部分熔融,并在岩浆上升的过程中受到有限的地壳混染的影响。晚侏罗世-早白垩世流纹质火山岩富集大离子亲石元素和轻稀土元素,并且比安山质-英安质火山岩具有更亏损的高场强元素,Eu异常明显亏损,具有正εHf(t)值(+4.3至+10.2)和Hf两阶段模型年龄(TDM2=910-544 Ma),另结合本区Hf同位素资料,表明岩浆来源于新元古代-早古生代新增生中-高钾玄武质地壳的部分熔融,并且岩浆经历了高度分异的演化过程。大兴安岭中段、兴安地块北部、额尔古纳地块主要地壳增生时期分别发生在新元古代-早古生代、新元古代和中-新元古代期间。大兴安岭中段的地壳增生具有与兴安地块北部和额尔古纳地块不同的增生史以及不同的地壳增生机制,暗示大兴安岭地区地壳增生的非均一性。通过与大兴安岭的岩浆作用时限对比分析,结合区域上构造特征、古地磁数据、多金属矿产分布等,将大兴安岭中段中生代岩浆作用的地球动力学机制概述如下:(1)早-中三叠世(250-240 Ma),古亚洲洋板块持续向北俯冲,形成了东西向的同碰撞花岗岩带和与俯冲相关的斑岩型Cu-Mo矿床,说明该期岩浆作用与古亚洲洋间的微陆块碰撞作用有关;(2)晚三叠世(235-205 Ma),大兴安岭中南段出现大量造山后花岗岩和磨拉石建造以及具有加厚下地壳埃达克岩属性的斑岩型铜钼矿,表明古亚洲洋在该区已经闭合,区域上处于古亚洲洋闭合后伸展环境;(3)早-中侏罗世(180-165 Ma),大兴安岭中段和吉黑东部出露的一套I型花岗岩,额尔古纳地块主要出露的弧形岩浆岩,松嫩地块东侧出现的“双峰式”火成岩组合和佳木斯地块西侧出现的南北向的斑岩型铜钼矿床,说明佳木斯地块-松嫩地块东侧的岩浆-成矿作用受伊佐柰琦板块向欧亚大陆俯冲作用影响,而大兴安岭中段岩浆作用主要与蒙古-鄂霍茨克洋板块南向俯冲有关;(4)晚侏罗世-早白垩世早期(155-138 Ma),该时期伊佐柰琦板块向北俯冲而蒙古-鄂霍茨克洋逐渐自西向东“剪刀式”闭合,大兴安岭中段岩浆作用与额尔古纳西侧的蒙古-鄂霍茨克洋板块断离和岩石圈拆沉引发的软流圈上涌有关;(5)早白垩世中晚期(137-115 Ma),大面积的高分异I型、A型花岗岩和多金属矿床分布于大兴安岭地区且岩浆年龄具有由南向北逐渐迁移的趋势,暗示大兴安岭中段岩浆作用主要受额尔古纳地块北部的蒙古-鄂霍茨克洋闭合后伸展作用的影响,而在松辽盆地及以东地区的岩浆-成矿作用主要受到伊佐柰琦板块折返导致的软流圈物质上涌的影响,两个构造域共同促使整个东北地区的岩浆-成矿大爆发。
Abstract
da xing an ling de chu zhong ya zao shan dai dong bu ,wei yu gu ya zhou xiang gou zao yu 、meng gu -e huo ci ke xiang gou zao yu he gu tai ping xiang gou zao yu zhi jian ,jing li le zhong duo wei liu kuai fu za de pin ge li shi he duo ci xiang -liu zhuai huan guo cheng ,zai wei liu kuai bi ge hou de zhong sheng dai shi ji you fa sheng le da gui mo yan jiang -cheng kuang zuo yong ,cong er cheng wei wo guo du te de huo shan yan dai 。you yu ji te shu de de li wei zhi ,da xing an ling huo shan yan cheng yin he de qiu dong li xue yan hua ji zhi deng yi zhi yi lai zuo wei de zhi xue jia de yan jiu re dian ,ran er zhe xie wen ti reng you jiao da zheng lun 。da xing an ling zhong duan de zhong sheng dai huo shan yan de ceng chu lou xiang dui wan zheng ,qin ru yan ye bian ji ge ge shi ji ,yin ci shi yan jiu da xing an ling zhong sheng dai yan jiang shi jian 、yan dan cheng yin he ji de qiu dong li xue ji zhi de li xiang chang suo 。ben wen tong guo da xing an ling zhong duan zhong sheng dai huo shan yan gao dan LA-ICP-MS U-Pbnian dai xue 、quan yan zhu liang 、wei liang yuan su he gao dan Hftong wei su de yan jiu ,zai qian ren yan jiu de ji chu shang lai tan tao da xing an ling zhong duan zhong sheng dai huo shan zuo yong ji ci 、yan dan cheng yin he gou zao yu dui gai ou ying xiang shi xian ,ling tong guo tong ji Hf-Ndtong wei su lai jie shi da xing an ling de ou de ke zeng sheng de li shi 。da xing an ling zhong duan zhong sheng dai huo shan zuo yong ji ci ke fen wei san ji :wan san die shi (235-225 Ma)、wan zhu luo shi -zao bai e shi (155-115 Ma),yan jiang zuo yong gao feng chu xian zai zao bai e shi zhong ji (125 Ma)。wan zhu luo shi -zao bai e shi yan jiang zuo yong mei you ming xian de jian duan ji ,ying wei huo shan pen fa zuo yong bu tong jie duan de jie guo 。da xing an ling zhong duan zhong sheng dai huo shan yan zhu yao wei ha da tao le gai zu 、man ke tou e bo zu 、ma ni tu zu 、bai yin gao lao zu he mei le tu zu de ceng 。ha da tao le gai zu huo shan zuo yong zhu yao xing cheng yu wan san die shi (235-225Ma),bing fei qian ren ren wei de zao san die shi ;man ke tou e bo zu he ma ni tu zu huo shan zuo yong fen bie xing cheng yu 155-140 Mahe 150-125 Mazhi jian ,man ke tou e bo zu he ma ni tu zu huo shan yan pen fa shi xian mei you ming xian ou fen ,dan man ke tou e bo zu huo shan zuo yong zhu ti wei wan zhu luo shi er ma ni tu zu huo shan zuo yong zhu ti wei zao bai e shi ;bai yin gao lao zu (135-120 Ma)he mei le tu zu (130-120 Ma)huo shan zuo yong zhu yao xing cheng yu zao bai e shi 。da xing an ling zhong duan tong ji de da liang wan zhu luo shi -zao bai e shi huo shan yan gao dan U-Pbnian ling xian shi ,zhi qian ding yi de tong yi ge zu de huo shan yan de ceng zai bu tong de ou de xing cheng shi dai cun zai “chuan shi xing ”,yi wang jin gen ju de ceng zu hua fen ke neng hui zao cheng huo shan yan xing cheng shi dai de wu pan ,ben wen ren wei yi “shi dai +yan xing ”de biao da fang shi geng kuo ge da xing an ling zhong sheng dai huo shan yan 。ha da tao le gai zu an shan zhi -ying an zhi huo shan yan ju you jiao gao de Srhan liang 、ruo de Eufu yi chang he jiao di de Yyi ji Yb,bu fen ju you jiao gao de MgOhan liang ,wei “ai da ke zhi yan dan ”。ying an yan shi tong guo tong ji an shan zhi yan jiang fen li jie jing xing cheng de 。de qiu hua xue te zheng xian shi chu ha da tao le gai zu huo shan yan fu ji qing xi tu yuan su he da li zi qin dan yuan su ,kui sun gao chang jiang yuan su de te zheng ,bing ju ju you zheng de εHf(t)zhi (+6.3zhi +12.7)he nian qing de er jie duan mo shi nian ling (858-452 Ma),biao ming yan jiang qi yuan yu xin yuan gu dai -zao gu sheng dai ji jian xin zeng sheng de de ke wu zhi de bu fen rong rong 。zhe xie te zheng shui ming ha da tao le gai zu huo shan yan lai zi ca chen xia de ke bu fen rong rong ,rong rong de yan jiang yu de man wu zhi fa sheng xiang hu zuo yong shi ai da ke zhi yan jiang ju you xiang dui gao MgOhan liang (Mg#zhi )。wan zhu luo shi -zao bai e shi an shan zhi -ying an zhi huo shan yan fu ji da li zi qin dan yuan su he qing xi tu yuan su ,bing kui sun gao chang jiang yuan su ,xian shi ruo huo mo Euyi chang ,ju you zheng εHf(t)zhi (+6.2zhi +13.4)he Hfchan jie duan mo xing nian ling (TDM1=556-270 Ma),yan jiang lai yuan yu xian qian fu chong liu ti jiao dai yan dan juan de man de bu fen rong rong ,bing zai yan jiang shang sheng de guo cheng zhong shou dao you xian de de ke hun ran de ying xiang 。wan zhu luo shi -zao bai e shi liu wen zhi huo shan yan fu ji da li zi qin dan yuan su he qing xi tu yuan su ,bing ju bi an shan zhi -ying an zhi huo shan yan ju you geng kui sun de gao chang jiang yuan su ,Euyi chang ming xian kui sun ,ju you zheng εHf(t)zhi (+4.3zhi +10.2)he Hfliang jie duan mo xing nian ling (TDM2=910-544 Ma),ling jie ge ben ou Hftong wei su zi liao ,biao ming yan jiang lai yuan yu xin yuan gu dai -zao gu sheng dai xin zeng sheng zhong -gao jia xuan wu zhi de ke de bu fen rong rong ,bing ju yan jiang jing li le gao du fen yi de yan hua guo cheng 。da xing an ling zhong duan 、xing an de kuai bei bu 、e er gu na de kuai zhu yao de ke zeng sheng shi ji fen bie fa sheng zai xin yuan gu dai -zao gu sheng dai 、xin yuan gu dai he zhong -xin yuan gu dai ji jian 。da xing an ling zhong duan de de ke zeng sheng ju you yu xing an de kuai bei bu he e er gu na de kuai bu tong de zeng sheng shi yi ji bu tong de de ke zeng sheng ji zhi ,an shi da xing an ling de ou de ke zeng sheng de fei jun yi xing 。tong guo yu da xing an ling de yan jiang zuo yong shi xian dui bi fen xi ,jie ge ou yu shang gou zao te zheng 、gu de ci shu ju 、duo jin shu kuang chan fen bu deng ,jiang da xing an ling zhong duan zhong sheng dai yan jiang zuo yong de de qiu dong li xue ji zhi gai shu ru xia :(1)zao -zhong san die shi (250-240 Ma),gu ya zhou xiang ban kuai chi xu xiang bei fu chong ,xing cheng le dong xi xiang de tong peng zhuang hua gang yan dai he yu fu chong xiang guan de ban yan xing Cu-Mokuang chuang ,shui ming gai ji yan jiang zuo yong yu gu ya zhou xiang jian de wei liu kuai peng zhuang zuo yong you guan ;(2)wan san die shi (235-205 Ma),da xing an ling zhong na duan chu xian da liang zao shan hou hua gang yan he mo la dan jian zao yi ji ju you jia hou xia de ke ai da ke yan shu xing de ban yan xing tong mu kuang ,biao ming gu ya zhou xiang zai gai ou yi jing bi ge ,ou yu shang chu yu gu ya zhou xiang bi ge hou shen zhan huan jing ;(3)zao -zhong zhu luo shi (180-165 Ma),da xing an ling zhong duan he ji hei dong bu chu lou de yi tao Ixing hua gang yan ,e er gu na de kuai zhu yao chu lou de hu xing yan jiang yan ,song nen de kuai dong ce chu xian de “shuang feng shi ”huo cheng yan zu ge he jia mu si de kuai xi ce chu xian de na bei xiang de ban yan xing tong mu kuang chuang ,shui ming jia mu si de kuai -song nen de kuai dong ce de yan jiang -cheng kuang zuo yong shou yi zuo nai qi ban kuai xiang ou ya da liu fu chong zuo yong ying xiang ,er da xing an ling zhong duan yan jiang zuo yong zhu yao yu meng gu -e huo ci ke xiang ban kuai na xiang fu chong you guan ;(4)wan zhu luo shi -zao bai e shi zao ji (155-138 Ma),gai shi ji yi zuo nai qi ban kuai xiang bei fu chong er meng gu -e huo ci ke xiang zhu jian zi xi xiang dong “jian dao shi ”bi ge ,da xing an ling zhong duan yan jiang zuo yong yu e er gu na xi ce de meng gu -e huo ci ke xiang ban kuai duan li he yan dan juan ca chen yin fa de ruan liu juan shang chong you guan ;(5)zao bai e shi zhong wan ji (137-115 Ma),da mian ji de gao fen yi Ixing 、Axing hua gang yan he duo jin shu kuang chuang fen bu yu da xing an ling de ou ju yan jiang nian ling ju you you na xiang bei zhu jian qian yi de qu shi ,an shi da xing an ling zhong duan yan jiang zuo yong zhu yao shou e er gu na de kuai bei bu de meng gu -e huo ci ke xiang bi ge hou shen zhan zuo yong de ying xiang ,er zai song liao pen de ji yi dong de ou de yan jiang -cheng kuang zuo yong zhu yao shou dao yi zuo nai qi ban kuai she fan dao zhi de ruan liu juan wu zhi shang chong de ying xiang ,liang ge gou zao yu gong tong cu shi zheng ge dong bei de ou de yan jiang -cheng kuang da bao fa 。
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标签:年代学论文; 中生代火山岩论文; 岩石成因论文; 地球动力学机制论文; 大兴安岭中段论文; 吉林大学2019-06-25论文;