镧系元素地球化学效应方程参数之科学意义初探——以山西晚古生代太原组8号煤层不同煤级的煤为例

Regression equation of geochemical effect of lanthanide and preliminary study on scientific significance of its parameters:An example of different types from No.8 coal seam,Shanxi Province,China

为量化给出以往发现的镧系元素地球化学效应的结果,运用镧系元素+3价离子半径与其某一地球化学行为参数的回归分析方法,研究了山西8号煤层气、肥、焦、廋、贫等5种烟煤镧系元素的地球化学行为,提出了镧系元素地球化学效应回归方程。初步推断认为,该方程可以反映任一地质体中某个镧系元素的任一可量化的地球化学或其他化学行为与该元素+3价离子半径以及该地质体中的∑REE,LREE/HREE之间的数学函数关系。其中,线性回归方程的斜率通常与其∑REE总量呈正相关,而幂函数的幂指数则与轻重稀土的分异程度呈高度正相关。但回归方程拟合优度的大小的地球化学意义尚难以确定,可能与地质体自然演化、变质过程某种热力学平衡程度有关,也与镧系元素自身的赋存状态和化学性质有关,但与演化、变质方向的关系尚难以确定。即便是同一演化或变质过程,LREE相比HREE达到平衡的程度亦不相同,通常LREE达到平衡的程度比HREE要高,但也有时候恰恰相反。其科学意义尚不清楚。如果是非自然的、人工干预的、快速的某种化学过程,如镧系元素的酸脱除率,由于远非充分的自然演化过程,因此亦远未能达到这种热力学平衡。此时回归方程虽然也适用,但拟合优度不高。

In order to quantify the results of geochemical effect of lanthanides discovered previously,the geochemical behaviors of lanthanides of five different types coal (including gas coal,fat coal,coking coal,lean coal and meagre coal) from No.8 coal seam,Shanxi Province,China,were investigated by the regression analysis between the trivalent ionic radii of lanthanides and their geochemical behaviors.Then the regression equation of geochemical effect of lanthanides was put forward.According to the preliminary results deducted by the author,this equation can reflect the mathematical relationship among any quantified geochemical or other chemical behaviors of lanthanides,the trivalent ionic of lanthanides radii,and the mathematical relationship between ∑REE and LREE/HREE in any geological body.Among these studies,the slop of liner regression equation is always positive correlation with the concentration of ∑REE and the power exponent of power function is significant positive with the differentiation extent of LREE and HREE.The goodness of fit of the regression equation may be associated with the degree of some thermodynamic equilibrium during the natural evolution and metamorphism of the geological body,and with the existing state and chemical properties of the lanthanides.However,how the evolution or metamorphism direction affects the goodness of fit is unclear.Usually,the degree of thermodynamic equilibrium of LREE is always higher than that of HREE in the same evolution or metamorphism process,but sometimes on the contrary,and the scientific significance is not clear.If the process is artificially-intervened and rapid (e.g.,the acid removal rate of lanthanide elements in coal),the thermodynamic equilibrium is hard to reach because it is far away from sufficient natural evolution.At this moment,the goodness of fit is relatively low although the regression equation is available.