A geophysical transect across the central Gulf of Mexico coastal plain shows that the early Paleozoic continental margin of southern Laurentia is preserved in a nearly pristine state beneath younger strata that were emplaced during the late Paleozoic Ouachita orogeny and formation of the modern Gulf of Mexico coastal plain. The thickness of the crystalline crust decreases abruptly across the ma...

Barite occurs throughout tlie gcologic ~.ecortl as massive beds, laminations, rosettes, and nodules. The niost importan( scientific and econo~iiic occurrences of barite are stratabound and stratifor~n massive betis from the Early Arcliean and tlie Early to Middle Paleozoic. Paleozoic beddecl barites are by far thc most volu~netricellp significant deposits in tlie geologic record. Additional occ...

For more than two decades, Jack Sepkoski’s hypothesis of three great ‘evolutionary faunas’ has dominated thinking about the Phanerozoic evolution of marine animals. This theory combines pattern description with process modelling: diversity trajectories of major taxonomic groups are sorted into three categories, and the trajectories are predicted by coupled logistic equations. Here I use a re-cr...

[1] A >500-km-long east-west trending metamorphic belt in the Qiangtang terrane of central Tibet consists of tectonic melange that occurs in the footwalls of Late Triassic–Early Jurassic domal low-angle normal faults. The melange is comprised of a strongly deformed matrix of metasedimentary and mafic schists that encloses lesser-deformed blocks of metabasites, Carboniferous–Triassic metasedimen...

U-Pb analyses of zircon from ten samples of augen gneisses, eight mafic and intermediate metaigneous rocks and six metasediments from some tectonic domains along the Calabria-Peloritani Terrane (Southern Italy) contribute to knowledge of peri-Gondwanan evolution from Late-Proterozoic to Paleozoic times. All samples were equilibrated under amphibolite to granulite facies metamorphism during the ...

The recent delineation of a vastly expanded Holocene paleo-lake (the Northern Darfur Megalake which was originally mapped as the West Nubian Paleolake and here will be referred to as WNPL–NDML) in Darfur in northwestern Sudan has renewed hopes for the presence of an appreciable groundwater resource in this hyper-arid region of Eastern Sahara. This paleolake which existed within a closed basin p...

Mass extinctions have altered the trajectory of evolution a number of times over the Phanerozoic. During these periods of biotic upheaval a different selective regime appears to operate, although it is still unclear whether consistent survivorship rules apply across different extinction events. We compare variations in diversity and disparity across the evolutionary history of a major Paleozoic...