摘要
湖北宜昌崆岭群孔兹岩系由富铝片岩-片麻岩及榴线英岩类、长英质岩类及镁铁质麻粒岩类组成,其原岩分别为黏土岩、砂岩-杂砂岩和泥灰岩,富铝片麻岩的稀土元素分配型式接近北美页岩组合样(NASC),Eu显示负异常,而Ce基本无异常。富铝片麻岩和榴线英岩的微量元素分配形式与澳大利亚后太古代页岩(PAAS)接近。根据风化参数CIW,与NASC、PAAS相近的稀土和微量元素的分布特征以及高w(LREE)/w(HREE)值与Eu负异常综合判断崆岭群孔兹岩系的原岩属于以花岗质岩石为蚀源区的陆屑沉积岩。根据富铝片麻岩和榴线英岩的δ(Ce)值(NASC标准化)及岩组中的石墨推断其原岩沉积环境为还原条件,根据δ(Ce)值(球粒陨石标准化)和镁铝含量比进一步判断其原岩沉积为大陆边缘的陆海过渡-海水沉积。由大量的碎屑沉积—少量化学沉积—有不同程度的化学沉积加入的大量碎屑沉积的沉积建造与岩组中石墨的变化推测该孔兹岩系原岩的形成可能与阜平、五台等旋回(期)的前吕梁旋回(期)黄陵-川中古陆块(或扬子陆块)的陆核形成有关。
The khondalite series within Kongling Group in Yichang City, Hubei Province are composed ot aluminum-rich schists-gneisses and garnet-sillimanite-quartzites, leptynite and mafic granulites, its protoliths are clay, sandstones-greywacke and marlite, REE distribution patterns of aluminum-rich gneisses incline NASC, Eu show negative abnormity and Ce displays no abnormity in chondrite-normalized REE distribution patterns. Trace element spide-grams of aluminum-rich gneisses and garnet-sillimanite-quartzites are close to PAAS. The protoliths of khondalite series within Kongling Group come from granitic rocks judging by weathering parameter CIW, REE distribution patterns and trace element spide-grams, high LREE/HREE and Eu negative abnormity. Ce/Ce ＊ （NASC-normalized） of aluminum-rich gneisses and garnet-sillimanite-quartzites and distribution of graphite indicates deoxy sedimentary environment. We can infer paralic-marine deposit of continental margin from Ce/Ce ＊ （chondrite-normalized） and the ratio of magnalium. Hence we can conclude that khondalite series may be related to the forming of core of Yangtze Plate during Luliang including Fuping, Wutai gyration（period） by sedimentary building and variety of graphite in lithohorizon.
出处
《地质科技情报》
CAS
CSCD
北大核心
2006年第5期41-46,共6页
Geological Science and Technology Information
基金
国家自然科学基金重点项目(40032010-B)
中国地质调查局项目(200113000017)
关键词
崆岭群
孔兹岩系
地球化学
大陆边缘
还原环境
Kongling Group
khondalite series
geochemistry
continental margin
deoxy sedimentary environment
