关于时间、沉积与地层学的几点思考

Thinking on time,sedimentation and stratigraphy

地层学与其他自然科学中的时间概念可区分为存在的时间和演化的时间两类,地层学就是依据这两类时间概念和标志构建地质学的时间坐标。选定百万年为地质学的基本时间单位在某种意义上来说是地层学的武断和盲从,它在一定程度上降低了地质学对精确性、严谨性的不懈追求。地层学完全能够在"存在的时间"和"演化的时间"中,依据自然规律和需要构建地质学的时间单位谱,如天、月、年以及岁差、斜度、偏心率周期等,建立与人类社会接轨的时间单位和地质学时间坐标。地层的形成作用可以区分为垂向加积和侧向加积作用以及它们的复合类型——生物加积和热侵位加积作用。由垂向加积作用形成的地层序列遵循地层学三定律(上新下老;水平叠置;侧向连续),岩性界面通常与等时面平行;由侧向加积作用形成的地层序列遵循瓦尔特相律和岩石地层单位穿时的普遍性原理,岩性界面通常与等时面斜交;而由生物加积和岩浆侵位加积作用形成的地层,其岩性界面与等时面的关系需要具体情况具体分析。

Time may be divided into both the being time and evolutional time in terms of stratigraphy and other natural sciences. The geological time scale is constructed by stratigrapher on the basis of above both times. We consider that the selection of Million years （Ma） as basic time unit for geology is somewhat arbitrary and following like sheep, which in a way has lowered geological pursuing for accuracy and preciseness. We think that stratigrapher can completely establish the time unit spectrum bridging million years to day and year for geology based on the both being and evolutional times, such as day, month, year, and precession, obliquity and eccentricity periods. Stratal sedimentation can be summarized as vertical and lateral accumulations and their compounds^-bioaccumulation and magmatic replacement accumulation. Strata formed by vertical accumulation obey the stratigraphical laws including the superposition, original horizontality and lateral continuity. Lithological boundary in strata formed by vertical accumulation usually parallels with synchroneity plane. Strata formed by lateral accumulation follow Walther＇s law and ubiquity principle of diachronism. Litbological boundary in strata formed by lateral accumulation usually does not parallel with synchroneity plane. The relationships between synchroneity plane and lithological boundary in strata formed by both bioaccumulation and magmatic replacement accumulation need particular analysis in each specific case.