BACK TO BASICS OF SEQUENCE STRATIGRAPHY: EARLY MIOCENE AND MID-CRETACEOUS EXAMPLES FROM THE NEW JERSEY PALEOSHELF

摘要

Many sequence stratigraphic approaches have used relative sea-level curves that are dependent on models or preconceived notions to recognize depositional sequences, key stratal surfaces, and systems tracts, leading to contradictory interpretations. Here, we urge following basic sequence stratigraphic principles independent of sea-level curves using seismic terminations, facies successions and stacking patterns from well logs and sections, and chronostratigraphic data to recognize sequence boundaries, other stratal surfaces, parasequences, and systems tracts. We provide examples from the New Jersey siliciclastic paleoshelf from the: 1) early Miocene using academic-based chronostratigraphic, seismic, core, downhole, and core log data, and 2) mid-Cretaceous using commercial well-log, seismic, and biostratigraphic data. We use classic criteria to identify sequence boundaries on seismic profiles by reflection terminations (onlap, downlap, erosional truncation, and toplap), in cores by surfaces of erosion associated with hiatuses detected using biostratigraphy and Sr-isotope stratigraphy and changes in stacking patterns, and in logs by changes in stacking patterns. Maximum flooding surfaces (MFSs) are major seismic downlap surfaces associated with changes from retrogradational to progradational parasequence stacking patterns. Systems tracts are identified by their bounding surfaces and fining-(generally deepening) and coarsening-(generally shallowing) upward trends in cores and well-log stacking patterns. Our Miocene examples of sequences m5.4 (17.7-16.1 Ma) and m5.8 (20.1-19.2 Ma) illustrate how basic sequence stratigraphic techniques reveal higher-order sequences within Myr scale composite sequences. Our mid-Cretaceous examples from the New Jersey shelf provide a paleoshelf transect spanning the Great Stone Dome to the outer continental shelf to identify parasequences, sequences, and systems tracts. This sequence stratigraphic framework provides insights into Myr scale