Abstract The morphology of Zygospira , an early atrypide brachiopod, was analyzed using a multivariate approach. Principal component analysis and discriminant clearly differentiated species as they are currently defined primarily based on differences in shell size ornamentation but not terms overall shape. older modesta able to persist into the late Katian (Richmondian) while smaller other brac...

The Ordovician global cooling trend observed by several temperature proxies, which coincides with one of the most significant evolutionary diversifications on Earth, is yet to be fully understood. This study presents new simulations pCO2 and surface temperatures using a spatially resolved climate-carbon cycle Earth system model fed refined continental reconstructions estimates solid degassing. ...

Volcanic rocks in the Miramichi inlier Maine occur two areas separated by Bottle Lake plutonic complex: Danforth segment (Stetson Mountain Formation) north of complex and Greenfield to south (Olamon Stream Formation). Both suites are dominantly pyroclastic, with abundant andesite, dacite, rhyolite tuffs subordinate lavas, breccias, agglomerates. Rare basaltic a small area tuffs, agglomerates, l...

Structures associated with Ediacaran-Ordovician alkaline magmatism and the timing of rare earth element (REE) mineralization in Wet Mountains, CO, were analyzed using field, geophysical, U-Th-Pb isotope methods to interpret their tectonic setting context previously proposed rift models. The Mountains are known for thorium REE failed rift-related, intrusions veins. Structural field data indicate...

Two new graptolite assemblages are identified from discrete intervals within the Phu Ngu Formation, Na Ri District, Bac Kan Province, north-east Vietnam. The graptolites occur in laminated mud/siltstones thought to be distal turbidite deposits. A low-diversity diplograptid sensu lato assemblage occurs mud-rich layers that interlaminated with silty and sandy horizons containing dendroid Dictyone...

Abstract Expanded ocean anoxia and global cooling have been invoked as major causal mechanisms for the Late Ordovician mass extinction, but factors underpinning extinction remain unresolved. Here, we document two intervals of particularly intense phosphorus recycling in marine rocks deposited across a bathymetric transect Yangtze Shelf Sea. The first occurred during initial phase and, coinciden...