一个湖泊－三角洲沉积总体中泥质岩成因地层研究的元素统计分析

将元素地球化学行为的一般规律与Ｒ因子分析、Ｑ聚类分析和Ｑ因子分析以及其它地质特征结合起来揭示出大庆油田东部外围中白垩统泉头组第三段和第四段湖泊－三角洲（水下部分）沉积总体泥质岩中各元素丰度及其比率受到盆体性因子（还原度Ｆ₁、酸度Ｆ₂）和盆围性因子（母岩Ｆ₃和胶体输入量Ｆ₄）的控制，最突出的表现是:Ｓｒ/Ｃａ与还原度和酸度正相关，ＣａＯ/ＭｇＯ与酸度负相关，Ｎｉ/Ｃｏ（或Ｎｉ、Ｃｒ）与还原度负相关，Ｔｉ/Ｖ与偏基性母岩影响强度负相关，Ｓｒ/Ｂａ与胶体输入量负相关。这些泥质岩可分成四类，与其中所夹粉砂岩（扩散流成因单位）一起分别构成水下河道周缘细屑沉积组合、滨浅湖沉积组合、前三角洲沉积组合和较深湖沉积组合，其沉积水深依次增加，氧化性和碱性依次减弱。偏基性母岩影响在水下河道周缘和前三角洲一带相对较强，在较深湖，因有导源于三角洲前缘的重力流发生，这种影响也时有表现。胶体输入量在所有沉积组合之间无特别明显的差异。

Element Statistical Analysis of Mudstones in a Lacustrine-Deltaic Depositional Pakage for Studies of Genetic Stratigraphy

At the third and fourth members of Quantou Group,Middle Cretaceous in the east of the neighbouring area of the Daqing oilfield, it is revealed that the element abundances and their ratios of mudstones in a lacustrine-deltaic (subaqueous)depositional pakage are controlled by basin-in factors(reducing F₁, acidity F₂) and basin-out factors (protolith F₃, colloid input F₄)while the general geochemical rules of the element behaviours are combined with R-mode factor,Q-mode cluster, Q-mode factor analyses and other geologic features, which are expressed conspicuously in correlations of Sr/Ca positive to reducing and acidity, CaO/MgO negative to acidity, Ni/Co negative to reduction, Ti/V negative to influence of basic protolith,Sr/Ba negative to colloid input. The mode cluster demonstrates that the mudstones are devided into four types, which with intercalated siltstones(spread flow genetic units)construct the subaqueous channal periphery fine sedimentary associations(SPF),coastal-shallow lake sedimentary associations(CSL),prodelta sedimentary associations(PDT) and deeper lake sedimentary associations(DPL) in an increasing depositional depth with water chemistry changing gradually from alkali and strongly oxidative to weakly alkali and oxidative. The basic protolith influences more strongly on the SPF and PDT than on the CSL and sometimes intensely on the DPL because of the gravity flows derived from the delta front. The colloid inputs are of not striking differences among all of the associations.