火成岩组合与构造环境:讨论  

Igneous Petrotectonic Assemblages and Tectonic Settings: A Discussion

作　　者：邓晋福[1,2] 肖庆辉[1,2] 苏尚国[1,2] 刘翠[1] 赵国春[1] 吴宗絮[1] 刘勇[1,2] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,岩石圈构造,深部过程及探测技术教育部重点实验室,北京100083 [2]中国地质调查局发展研究中心

出　　处：《高校地质学报》2007年第3期392-402,共11页Geological Journal of China Universities

基　　金：国土资源部计划项目(1212010633902;1212010633903;1212010711814);国家自然科学基金重点项目(40234048)

摘　　要：讨论了不同构造环境下的火成岩组合:(1)洋中脊扩张,(2)洋岛,(3)岛弧,(4)MORS型和SSZ型蛇绿岩,(5)活动大陆边缘弧,(6)与俯冲作用有关的火成岩弧的组成极性,(7)大陆碰撞,(8)大陆裂谷,(9)稳定的克拉通或地台等环境的火成岩组合。强调不同作者采用不同的参数坐标定义的拉斑玄武岩系列(TH),钙碱性系列(CA)和碱性系列(A)等学术含义的差别,指出不要因为在语言书写上的相同混淆了它们在学术含义上的差别,而造成有关构造环境识别的误解。探讨了识别洋中脊扩张型(MORS)和洋俯冲带上面(SSZ)蛇绿岩(套)在火成岩组合上的差别。基于高温高压实验成果,提出定义高镁安山岩(HMA)时,对应于w(SiO2)的w(MgO)的最低值(表2)。讨论了镁安山岩—英安岩(MAD)和埃达克岩(adakite)的术语,建议采用Kay(1978)的镁安山岩—英安岩来定义(而不是用adakite来定义)俯冲洋壳板片局部熔融产生的岩浆,认为具高Sr/Y,低FeO/MgO,高MgO,高Ni,Cr的镁安山岩—英安岩才能满足板片熔浆(slab-melt)特征的要求,而不是只强调高Sr/Y这个指标。根据有关大陆碰撞造山的不同分类方案及其术语的确切含义,强调了后造山与大陆裂谷环境的A型/r的识别在于前者与CA/r共生,后者则无CA/r共生,A与CA的学术含义是Peacock钙碱指数的分类。This paper discusses igneous petrotectonic assemblages of various tectonic settings： 1. mid-ocean ridge spreading; 2. oceanic island; 3. island arc; 4. MORS-type and SSZ-type ophiolites; 5. active coutineutal marginal arc; 6. compositional polarity of subduction-related magmatic arcs; 7. continental collision; or platform, etc. It is emphasized that the tholeiitic （ TH ）, calc-alkaline （ CA ） and 8. continental rift; 9. stable craton alkaline （ A ） series defined from various parameters by different authors have different scientific meanings. In this paper it is indicated that the same written terms of TH, CA and A but with various meanings could easily result in abuse of these terms, especially for the recognition of the tectonic settings. The difference between MORS- and SSZ-type ophiolites in terms of igneous petrotectonic assemblages is discussed. The lowest MgOwt% of the HMA is suggested （ Table 2 ）, based on the data of petrological experiments. The terms of magnesian andesite-dacite and adakite are discussed, and in turn, the Kay＇s magnesian andesite-dacite of higher Sr/Y, lower FeO/MgO, and higher MgOwt% as well as higher Ni, Cr contents, are comprehensively used, which can be more satisfactory to define the slab-melt, rather than the single parameter of high Sr/Y. The various schemes of classification for the continental collision are indicated, and it is necessary to be careful for using these schemes. The post-orogenic and the continental rifting A type granites are suggested to be associated with or without the CA/r, respectively, and the meaning of A and CA, here, is determined by the Peacock＇s alkali-lime index.

关 键 词：火成岩组合 构造环境 TH/CA/A系列 高镁安山岩 镁安山岩—英安岩 大陆碰撞造山 

分 类 号：P588.1[天文地球—岩石学] P54[天文地球—地质学]