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Late Ordovician graptolite mass mortality has been examined closely in only a few continuous stratal succession. These sections include those at Dob's Linn, Scotland; Anhui, China; and Mirny Creek, USSR. Correlations among these areas are not precise; however, many characteristic Late Ordovician graptolites appear to persist longer in the Anhui area than at either Dob's Linn or Mirny Creek. Graptolites...
The vast majority of oceanic biomass lives in the surface wind-mixed layer (0–100 m) of the ocean, trophically dependent on light or primary production based on photosynthesis. Waters from the main pycnocline (100–1000 m) or deeper naturally contain decay products from sinking organic matter as a function of the oxidation state of the waters. Such products, in proper concentrations, can inhibit photosynthetic...
Isotopic and elemental proxies are useful for discerning the original compositions of ancient rocks subject to later diagenetic/thermal alteration, low-rank metamorphism, outcrop weathering, etc. Recent work in the Cariaco Basin [Chem. Geol. 195 (2003) 131] has shown a high correlation between total organic carbon (TOC) content and Mo normalized to Al in these modern euxinic sediments: microlaminated,...
The whole-rock cerium anomaly, tested for outer shelf-upper slope stratigraphic sections from the middle Ordovician through the lower Silurian of Scotland, is proposed as an empirical technique to develop a eustatic 3rd-order or finer-scale sea-level curve. This interval was chosen as it straddles the well-documented Late Ordovician glaciation and can be defined by graptolite zones. The anomaly...
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