The Cretaceous/Paleogene (K/Pg) boundary is marked by one of the largest mass extinctions in Earth’s history, with geological evidence for this event being expressed hundreds locations worldwide. An extensively studied section located near El Kef, northwestern Tunisia, characterized classic iridium-rich K/Pg layer, abundant and well-preserved microfossils, apparently continuous sedimentation th...

Subsurface modeling from seismic and borehole data is important for reservoir prediction, geophysical exploration, and production. A reasonable model should honor borehole rock properties and conform to seismic structural and stratigraphic features. Such a subsurface model can be difficult to build in cases complicated by faults and unconformities. Automatic and semiautomatic methods have been ...

Geological mapping of the area around Baltis Vallis, the longest (6,800 km) canali-type channel on Venus, has led to the determination of stratigraphic relations which appear to be consistent over this entire region comprising -20 x 106 km 2 or -5% of the total surface of Venus. The most abundant unit in the study area, plains with wrinkle ridges (Pwr), consists of two subunits separated by the...

For the microbiostratigraphical studies, a stratigraphical section (named Dareh-Goshayesh) has been selected in southeast of Maragheh, Northwestern Iran. The thickness of successions in the selected stratigraphic section is measured about 223.6 m. The mentioned studied stratigraphic section is composed of two clastic and carbonate units. This succession unconformably overlies the Lar Formation ...

For the lithostratigraphy and microbiostratigraphical studies, a stratigraphical section (named Dareh-Goshayesh) has selected and is located in southeast of Maragheh city, south of eastern Azerbaijan province in the northwest of Iran. The thickness of successions in the selected stratigraphic section is measured about 223.6 m. The mentioned studied stratigraphic section is composed of two clast...

—We present a quantitative analysis of megafloral turnover across the Cretaceous/Paleogene boundary (K/T) based on the most complete record, which comes from the Williston Basin in southwestern North Dakota. More than 22,000 specimens of 353 species have been recovered from 161 localities in a stratigraphic section that is continuous across and temporally calibrated to the K/T and two paleomagn...

FIG. 1.—Alternative explanations of strata exhibiting progradational followed by retrogradational stacking. In Interpretation 1, the switch in stacking patterns is interpreted as a combined type I sequence boundary (SB(I)) and transgressive surface (TS), underlain by the highstand systems tract (HST) and overlain by the transgressive systems tract (TST). In Interpretation II, the switch in stac...

S U M M A R Y Estimating orientations of seismic structures (reflections) and stratigraphic features (channels) is important for seismic interpretation, subsurface interpolation and geophysical inversion. Structure tensors, constructed as smoothed outer products of amplitude gradients, are commonly used to estimate seismic reflection normals, which uniquely define the reflection orientations. H...

Abstract Methods to determine the ages of period and stage boundaries geologic time scale (GTS) have a long history continue be steadily improved. Stage boundary age estimates are now accompanied by error bars showing stratigraphic uncertainty. Most GTS2004, GTS2012 GTS2020 results involved cubic spline-curve fitting, in this study, Ordovician through Cretaceous smoothing splines spliced togeth...

Many of the largest earthquakes are generated at subduction zones or other plate boundary fault systems near enough to the coast that marine environments may record evidence of them. During and shortly after large earthquakes in the coastal and marine environments, a spectrum of evidence may be left behind, mirroring onshore paleoseismic evidence. Shaking or displacement of the seafloor can tri...