CAJ | 학술논문

通过野外地质调查和系统的岩石化学、常量元素、微量元素以及稀土元素等研究,探讨了藏南彭错林硅质岩的地球化学特征及其沉积环境.研究表明,呈厚层状产出的绿色、棕褐色硅质岩具有较高的SiO_2含量,局部受Fe、Mn矿化,Al/(Al+Fe+Mn)比值小,在Fe-Mn-Al三角成因判别图解中,大部分硅质岩样品落入热水沉积区域,微量元素Sr、Zr、Cu、Zn和Ba含量较高,稀土元素∑REE较低,Ce负异常,Eu正异常,北美页岩标准化后配分模式稍向左倾,体现出热水沉积特征;在沉积环境判别图100×Fe_2O_3/SiO_2 100×Al_2O_3/SiO_2、Fe_2O_3/(100-SiO_2)-Al_2O_3/(100-SiO_2)和Fe_2O_3/TiO_2-Al_2O_3/(Al_2O_3+Fe_2O_3)中,硅质岩样品投影到洋中脊和深海区域,说明形成于大洋中脊和深海盆地环境;硅质岩常量和稀土参数变化特征图显示,在剖面中P-L-、P-L-5和P-L-7采样位置更接近热液中心;硅质岩的形成与板块的汇聚消减产生的以洋中脊和海底热点为中心的洋壳热水系统有关.
통과야외지질조사화계통적암석화학、상량원소、미량원소이급희토원소등연구,탐토료장남팽착림규질암적지구화학특정급기침적배경.연구표명,정후층상산출적록색、종갈색규질암구유교고적SiO_2함량,국부수Fe、Mn광화,Al/(Al+Fe+Mn)비치소,재Fe-Mn-Al삼각성인판별도해중,대부분규질암양품락입열수침적구역,미량원소Sr、Zr、Cu、Zn화Ba함량교고,희토원소∑REE교저,Ce부이상,Eu정이상,북미혈암표준화후배분모식초향좌경,체현출열수침적특정;재침적배경판별도100×Fe_2O_3/SiO_2 100×Al_2O_3/SiO_2、Fe_2O_3/(100-SiO_2)-Al_2O_3/(100-SiO_2)화Fe_2O_3/TiO_2-Al_2O_3/(Al_2O_3+Fe_2O_3)중,규질암양품투영도양중척화심해구역,설명형성우대양중척화심해분지배경;규질암상량화희토삼수변화특정도현시,재부면중P-L-、P-L-5화P-L-7채양위치경접근열액중심;규질암적형성여판괴적회취소감산생적이양중척화해저열점위중심적양각열수계통유관.
The geochemical characteristics and depositional environment of Pengcuolin chert are studied based on the field investigations and analysis on major elements, trace elements and rare earth elements. The massive chert is green and brown, being high in SiO_2 content, locally enriched in Fe and Mn, Al/(Al+Fe+Mn) ratio being low. In Fe-Mn-Al triangle diagrams, most chert samples fall into the hydrothermal region. Trace elements such as Sr,Zr,Cu,Zn and Ba are higher and ΣREE is lower, with Ce negative anomaly and Eu anomaly. Their NASC-normalized REE distribution patterns are slightly left-leaning, indicating their hydrothermal origin. In sedimentary environment discrimination diagrams such as 100×Fe_2O_3/SiO_2-100×Al_2O_3/SiO_2, Fe_2O_3/(100-SiO_2)-Al_2O_3/(100-SiO_2) and Fe_2O_3/TiO_2-Al_2O_3/(Al_2O_3+Fe_2O_3), chert samples fall into the areas of the mid-ocean ridges or deep-sea. In parameter variation diagrams, samples of PCL-1,PCL-5 and PCL-7 are closer to the hydrothermal center. It is shown that the Pengcuolin chert, southern Tibet was formed by the hydrothermal systems at convergence and subduction sites of plates.