松辽盆地北部上二叠统林西组地球化学特征及地质意义

为探讨松辽盆地北部林西组地球化学特征、沉积环境及构造背景，对该区黑富地1井所钻遇的上二叠统林西组暗色泥质板岩进行主量元素、微量元素和稀土元素测试分析，结果表明：样品主量元素平均质量分数SiO₂为65.05%、Al₂O₃为17.23%、CaO为2.58%、Na₂O为2.84%、K₂O为3.29%，K₂O/Na₂O值为0.20~3.48，A1₂O₃/（CaO+Na₂O）值为0.41~8.01；稀土元素w（∑REE）值介于80.68×10^-6~215.59×10^-6之间，平均值为173.41×10^-6，δEu值介于0.61~0.88之间，平均值为0.70，表现为Eu的负异常，δCe值介于0.91×10^-6~1.01×10^-6之间，为微弱的Ce负异常，LREE富集，HREE亏损；微量元素以亏损Nb、Ta、Sr，相对富集Rb、Ba、La、Ce、Pb、Nd、Sm为特征。样品元素分析和物源w（TiO₂）-w（Ni）、La/Th-w（Hf）等判别图解表明，林西组沉积物源具有多样性，主要来源于上地壳长英质物源，还有少量来自中、基性岩火成岩物源区。样品微量元素标准化蛛网图，稀土元素球粒陨石标准化配分模式图，K₂O/Na₂O-w（SiO₂）、Th-Co-Zr/10、F₂-F₁构造背景判别图及地球化学参数对比结果表明，松辽盆地北部林西组物源构造背景主要为活动大陆边缘和大陆岛弧，可能形成于靠近大陆岛弧的活动大陆边缘构造背景。林西组应形成于海陆过渡相到陆相环境，水体由半咸水逐渐转变为淡水。

Geochemical Characteristics and Geological Significance of Upper Permian Linxi Formation in Northern Songliao Basin

Experimental data of the major elements, trace elements and rare earth elements of the dark argillaceous slate from the Upper Permian Linxi Formation in Well Heifudi 1 of the northern Songliao basin were examined so as to discuss the geochemical characteristics, sedimentary environment and tectonic background of the Linxi Formation. The average content of major elements is SiO₂=65.05%, Al₂O₃=17.23%, CaO=2.58%, Na₂O=2.84%, and K₂O=3.29%. K₂O/Na₂O is 0.20-3.48, and A1₂O₃/(CaO+Na₂O) is 0.41-8.01. The ΣREE is between 80.68×10^-6 and 215.59×10^-6 (average 173.41×10^-6), the δEu negative anomaly is between 0.61 and 0.88 (average 0.70), and the Ce negative anomaly is between 0.91×10^-6 and 1.01×10^-6, relatively weak. The clastic rocks are characterized by LREE enrichment and HREE depletion. The trace elements are characterized by a loss of Nb, Ta, and Sr, and are relatively rich in Rb, Ba, La, Ce, Pb, Nd, and Sm. The elemental analysis of core samples and the results of w(TiO₂)-w(Ni)and La/Th-w(Hf)indicate that the sediment source of Linxi Formation is diverse, mainly from felsic rock of the upper crust with a minority of intermediate-basic igneous provenance. The results of trace element standardized spider web map, rare earth element chondrite standardized partition pattern,diagrams of K₂O/Na₂O-w(SiO₂), Th-Co-Zr/10, F₂-F₁ structural background discrimination,and geochemical parameters comparison indicate that the provenance of Linxi Formation in Well Heifudi 1 is mainly from active continental margin and continental island arc,which would like be formed in the marine-terrestrial transitional to terrestrial environment.