Applications of miospore quantitative stratigraphy and cyclostratigraphy in the Neocomian - Cenomanian sediments in the Western Desert, Egypt: A step in the way to biochronostratigraphy

摘要

The Lower Cretaceous section in the Western Desert witnesses regular petroleum exploration activities and contains active petroleum systems. The main tool for biostratigraphic classification of these important strata is the palynology based biozonation. The classical biozonation methods that rely on the ranges between only selected zonal palynomorphs markers or bioevents cause many problems in the correlation of the stratigraphic units. These problems slowed the development of a unified scheme and constructions of a time scale. In this study, another approach is introduced for the first time to overcome these problems. This approach depends on analytical stratigraphy that is based on a number of quantitative methods in the framework of the geomathematics. These quantitative methods include statistical constrained single linkage cluster analysis, graphic correlation, constrained optimization, ranking and scaling and unitary associations. These methods take into account all of the identified taxa bioevents or their co-existences. Each of these methods produces a biozonation that predict the real distribution of the palynomorphs in time and space in a different approach. In addition, these methods rank and scale the taxa bioevents in a way that can be calibrated to a time scale. The resulted biozonations are comparable through the methods. The study is based on the miospore records of 15 wells that are closely spaced to become the center for future correlations. This is an important step toward the biochronology that add the time dimension to the biostratigraphic analysis. In addition, the present study introduces for the first time the astronomical time calibration in Bassel-1 well based on the principles of cyclostratigraphy including time series analysis and age model tuning. The G-ray log of this well is tuned to 405 kyr eccentricity cycle to produce an age model that anchored on the OAEs. The age model can be developed by additional calibration and tuned to a higher resolution and used in other applications.