APPLYING CYCLOSTRATIGRAPHY FOR BETTER CORRELATION RESULT AND COMPARISON WITH SEQUENCE STRATIGRPHY

摘要

This research is about an effort to formulate correlation method which involves sequence stratigraphy analysis which commonly used in addition to the relatively-new stratigraphic subdivision is called "cyclostatigraphy". Nio et al (2005) introduces the cyclostratigraphy method called "spectral-analysis" (INPEFA). Basically, both methods sequence stratigraphy and cyclostratigraphy are tools to define a chronostratigraphy with a different point of view about changes of accommodation. Sequence stratigraphy concept states that the relative sea level interacts with eustacy and tectonic, whereas cyclostratigraphy concept proposes that variation of cycles in sedimentary records is influenced by global sea level (Milankovitch Cycles). The curiosity of this analysis comes from the question whether the research object is influenced by Milankovitch cycles only or also by tectonics. The Samarinda outcrops are used in this research. The stratigraphic profile from measuring section would be digitized in Grain Size log as the GR log substitution. From the stratigraphic profile, the bounding surfaces and system tracts are defined with sequence stratigraphy concept. Then, the Grain Size log would be sampled to construct Grain Size predicted log by linear regression. The difference between the both logs result in Prediction Error Filter Analysis (PEFA). The integrated PEFA is called Integrated PEFA log (INPEFA) as a tool to determine cyclostratigraphy. The experiment result is overprinting of bounding surfaces both methods that interpreted as a natural matter because the stratigraphic profile is influenced by cycles, either by eustatic cycle only or also by tectonics. From these findings, cyclostratigraphy-INPEFA can be used to support the sequence stratigraphy analysis in subsurface data with more confidence and accuracy.