Jurassic Unconformities, Chronostratigraphy, and Sea-Level Changes from Seismic Stratigraphy and Biostratigraphy

摘要: Seventeen global unconformities and their correlative conformities (sequence boundaries) subdivide the strata of Jurassic earliest Cretaceous into genetic depositional sequences produced by 16 eustatic cycles. These cycles make up supercycle. Eight are both subaerial submarine (Type 1), believed to have been caused rapid falls sea level. Nine only 2), be related slow In addition, marine condensed sections (starved intervals) identified. interpreted rises Unconformity recognition is locally or regionally enh nced periodic truncation folded faulted during sea-level lowstands onlap onto topographic highs highstands, but we find no evidence that tectonics unconformities. The supercycle correspond chronostratigraphic intervals a series sequences, which recognizable from seismic, well, outcrop data. stratal facies patterns between them interaction basement subsidence, changes sea-level, varying sediment supply. Detailed analyses sediments with seismic stratigraphy well data permit quantification subsidence history reconstruction paleoenvironment through time. integrated use biostratigraphy provides better geologic age than could obtained either method alone. Paleobathymetry, facies, relative level can confirmed, improved on, control. Geohistory analysis based on time-depth diagrams quantitative total basi subsidence. When this corrected for compaction loading, tectonic long-term may determined. Short-term, demonstrated stratigraphic resolution these rarely allows exact magnitude, minimum rate change often