New perspectives on graptolite distributions and their use as indicators of platform margin dynamics

Carbon isotope chemostratigraphy of the Llandovery in Arctic Canada: Implications for global correlation and sea-level change

“…Wenzel & Joachimski (1996), Brenchley et al (2003), and some other authors proposed that the Hirnantian and Sheinwoodian events were caused by increased primary productivity in the surface ocean waters and increased organic carbon storage in the sediments and/or deep ocean waters. However, as noted by Melchin & Mitchell (1991), Hallam & Wignall (1997), and Munnecke et al (2003), sediments comprising the Hirnantian glacial interval are characterized globally by lower concentrations of organic matter compared to overlying and underlying strata, and this is seen in distal shelf settings (e.g., Cornwallis Island, Melchin & Holmden in press), deep slope and continental rise environments (e.g., Finney & Berry 1997;Finney et al 1999), and Dob's Linn, which is now widely accepted to represent deep sea sediments deposited on oceanic crust, preserved in an accretionary prism setting (Leggett 1987;Stone & Merriman 2004). This is more consistent with decreased, as opposed to increased, rates of organic carbon burial in the world's oceans.…”

Upper Llandovery–Wenlock (Silurian) palynology of the Pentland Hills inliers, Midland Valley of Scotland

“…The influx of taxa is considered to be an environmental response rather than a preservational effect as there is no apparent difference in preservation between acritarchs from the lower and upper parts of the formation. One possibility is that acritarch microfloras track changes in the location of certain physical and chemical properties of water-masses, for example nutrient availability, salinity, temperature, through time, in a manner analogous to the way in which graptolite faunas track changes in the location of their preferred position on continental margins (Finney & Berry 1997Goldman et al 1999) Wellman & Richardson (1993) and this paper; data for the Knockgardner Sandstone Formation are from Dorning (1982); data for the Straiton Grits Formation are from Dorning (1982) and this paper. …”

Diversity and paleobiogeographic distribution patterns of early and Middle Ordovician graptolites in distinct depositional environments of South China

“…The Ordovician graptolite diversity pattern of South China resembles that of the Vinini Formation in north-central Nevada, USA, where the maximum diversity is also above continental margin [48]. This pattern may be closely related with the upwelling that contains rich nutrients and commonly occurs in this oceanic region, as well as the generation of anoxic (or anaerobic) water mass [48][49][50].…”