Method of identifying Milankovitch cycle quantitatively

Abstract

The invention relates to a method of identifying Milankovitch cycle quantitatively. The method comprises the following steps of (1) selecting Gamma ray as a proxy indicator of Milankovitch cycle identification; (2) pre-processing Gamma data; (3) identifying theoretical orbital cycle value so as to acquire a theoretical cycle set M; and (4) identifying Milankovitch cycle in stratum, the specific process comprises following steps of first, organizing Gamma data in a target stratum; second, performing spectrum analysis on Gamma data in a selected stratum; and third, matching so as to obtain Milankovitch cycle and cycle thickness corresponding to the Milankovitch cycle.

Description

technical field [0001] The invention relates to a method for quantitatively identifying Milankovitch periods, which belongs to the technical field of geological formations. Background technique [0002] Periodic changes in the geometry of the Earth's orbit control climate change and also have an important impact on sediment filling. Milankovitch's quantitative description of the relationship between orbital elements (eccentricity, slope, and precession) and climate is the development of cycle stratigraphy. Periods corresponding to important milestones, eccentricity, slope and precession are collectively referred to as Milankovitch periods. There is a relatively stable proportional relationship between all levels of Milankovitch cycles, and this ratio should be consistent with the ratio of stratigraphic cycle thicknesses at all levels in strata with relatively integrated stable depositional environments. This is also the basis of Milankovitch cycle research. Cores from stab...

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Problems solved by technology

At present, the key link to this is mainly based on the approximate comparison between the theoretical period ratio and the frequency ratio. It is considered that the two are close, which belongs to qualitative analysis and judgment. If the degree of proximity between the two is not quantitatively determined, it is impossible to explain whether there is any A closer combination of proportions, which will cause a bias in the identified Milankovitch cycle

When the target stratum to be analyzed is thicker, there are more peak frequencies obtained by spectrum analysis, and there are more combinations of proportional relationships between corresponding frequencies. It is time-consuming and difficult to find the best match through qualitative analysis.

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