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...

Colonization of the land by plants most likely occurred in a stepwise fashion starting in the Mid-Ordovician. The earliest flora of bryophyte-like plants appears to have been cosmopolitan and dominated the planet, relatively unchanged, for some 30 million years. It is represented by fossilized dispersed cryptospores and fragmentary plant remains. In the Early Silurian, cryptospore abundance and...

Mass extinction events are recognized by increases in extinction rate and magnitude and, often, by changes in the selectivity of extinction. When considering the selective fingerprint of a particular event, not all taxon extinctions are equally informative: some would be expected even under a 'background' selectivity regime, whereas others would not and thus require special explanation. When ev...

The end-Ordovician was an enigmatic interval in the Phanerozoic, known for massive glaciation potentially at elevated CO2 levels, biogeochemical cycle disruptions recorded as large isotope anomalies and a devastating extinction event. Ice-sheet volumes claimed to be twice those of the Last Glacial Maximum paradoxically coincided with oceans as warm as today. Here we argue that some of these rem...

Four metasedimentary zircon populations from different tectonometamorphic units of the Central and the Northern Schwarzwald (Variscan belt, SWGermany) were investigated using SEM, cathodoluminescence and SHRIMP dating. Despite partially strong modifications of primary internal morphologies during Variscan metamorphism at amphibolite (750 C, 0.4– 0.6 GPa) and granulite-facies conditions (950–1,0...

One of the characteristic features of Ordovician tectonism in the east Lachlan Fold Belt is the occurrence of calcalkaline to shoshonitic basalts, which have been recognised as part of an intraoceanic arc environment (Glen et al. 1998), consistent with early tectonic interpretations (Oversby 1971; Scheibner 1973). Aside from typical traceelement abundances of intraoceanic arcs, critical evidenc...

Cladistic parsimony analysis of the trilobite family Homalonotidae Chapman 1980 produced a hypothesis of relatedness for the group. The family consists of three monophyletic subfamilies, one containing Trimerus Green 1832, Platycoryphe Foerste 1919, and Brongniartella Reed 1918; one containing Plaesiacomia Hawle and Corda 1847 and Colpocoryphe Novák in Perer 1918; and one containing Eohomalonot...

The provenance of the upper Cambrian to Upper Ordovician sedimentary rocks Tasmania and Waratah Bay in southern Victoria provides information about complex dynamic tectonic environment present during their deposition. This paper uses U–Pb detrital zircon data constrain stratigraphic comparisons reconstructions these rock sequences. Multivariate statistics are used investigate similarity between...

Glacial episodes have been linked to Ordovician-Silurian extinction events, but cooling itself may not be solely responsible for these extinctions. Teratological (malformed) assemblages of fossil plankton that correlate precisely with the extinction events can help identify alternate drivers of extinction. Here we show that metal poisoning may have caused these aberrant morphologies during a la...