The Turonian Notom Delta is one of the Ferron fluvial-deltaic wedges deposited in the foreland basins of the Cretaceous Seaway of North America.The wedge is exposed three dimensionally in the Henry Mountains region Ut...The Turonian Notom Delta is one of the Ferron fluvial-deltaic wedges deposited in the foreland basins of the Cretaceous Seaway of North America.The wedge is exposed three dimensionally in the Henry Mountains region Utah,USA.High-resolution sequence stratigraphic analysis along a 35 km dip-oriented outcrop belt shows that the wedge consists of six depositional sequences.Ammonite and Inoceramid biostratigraphy and 40Ar/39Ar age dating of various bentonites show that the wedge was deposited from 91.25 Ma to 90.63 Ma,an interval of merely 0.62 Ma.Assuming each sequence is formed over a similar time span,each sequence,thus,represents about 105 yr,suggesting high-frequency depositional sequences.Amplitude of relative sea-level changes,built on shoreline trajectory,is 2-61 m,with an average of only 20 m.Fluvial incision during high-frequency and low-amplitude relative sealevel fall is mainly around the highstand prism.Incision diminishes rapidly up dip and down dip,and the resultant incised valleys are narrow and shallow.Such sea-level fluctuations also result in small,stratigraphically complex shoreline sandstones that need special attention during hydrocarbon exploration.展开更多
文摘The Turonian Notom Delta is one of the Ferron fluvial-deltaic wedges deposited in the foreland basins of the Cretaceous Seaway of North America.The wedge is exposed three dimensionally in the Henry Mountains region Utah,USA.High-resolution sequence stratigraphic analysis along a 35 km dip-oriented outcrop belt shows that the wedge consists of six depositional sequences.Ammonite and Inoceramid biostratigraphy and 40Ar/39Ar age dating of various bentonites show that the wedge was deposited from 91.25 Ma to 90.63 Ma,an interval of merely 0.62 Ma.Assuming each sequence is formed over a similar time span,each sequence,thus,represents about 105 yr,suggesting high-frequency depositional sequences.Amplitude of relative sea-level changes,built on shoreline trajectory,is 2-61 m,with an average of only 20 m.Fluvial incision during high-frequency and low-amplitude relative sealevel fall is mainly around the highstand prism.Incision diminishes rapidly up dip and down dip,and the resultant incised valleys are narrow and shallow.Such sea-level fluctuations also result in small,stratigraphically complex shoreline sandstones that need special attention during hydrocarbon exploration.
