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Achim D. Herrmann
Louisiana State University
47Publications
13H-index
777Citations
Publications 49
Newest
#1Wenkun Qie (CAS: Chinese Academy of Sciences)H-Index: 7
#2Thomas J. Algeo (UC: University of Cincinnati)H-Index: 31
Last.Achim D. Herrmann (LSU: Louisiana State University)H-Index: 13
view all 4 authors...
Abstract The Late Paleozoic (Early Devonian to Middle Permian) was an interval of profound changes in Earth-surface systems, reflected in dynamic interplay among the biosphere, hydrosphere, atmosphere, and geosphere. Major events transpired, including the colonization of landmasses by vascular plants, the assembly of the supercontinent Pangea, two first-order mass extinctions (the Frasnian-Famennian and Devonian-Carboniferous boundary events), and the most severe icehouse climate mode of the Pha...
1 CitationsSource
#1Achim D. Herrmann (LSU: Louisiana State University)H-Index: 13
#2James E. Barrick (TTU: Texas Tech University)H-Index: 12
Last.Yongbo Peng (LSU: Louisiana State University)H-Index: 13
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Abstract Climatic and glacio-eustatic information for the Late Paleozoic Ice Age is often extracted from cyclothems of the Midcontinent of North America. Although it is recognized that these important archives of global climate and environmental change are the result of waxing and waning of Gondwanan glaciers that produced widespread transgressive-regressive events, the relationships of conodont biofacies to changes in water depth, water chemistry, and other environmental parameters remain in di...
2 CitationsSource
#1Adam C.E. Turner (LSU: Louisiana State University)H-Index: 1
#2Thomas J. Algeo (UC: University of Cincinnati)H-Index: 31
Last.Achim D. Herrmann (LSU: Louisiana State University)H-Index: 13
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Abstract The North American Midcontinent Sea (NAMS) reached its maximum extent during glacio-eustatic highstands of the Late Paleozoic Ice Age, during which organic-rich “core shales” accumulated under a stratified water column with anoxic deep waters. The core shales of cyclothems are composed of a lower organic-rich laminated black shale and an upper bioturbated gray shale. The present study investigates circulation patterns within the NAMS by examining secular variations and spatial gradients...
2 CitationsSource
#1Alexander D. Reyes-Avila (LSU: Louisiana State University)H-Index: 1
#2Edward A. Laws (LSU: Louisiana State University)H-Index: 50
Last.Thomas P. Blanchard (LSU: Louisiana State University)H-Index: 1
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1 CitationsSource
#1John Michael Callen (LSU: Louisiana State University)
#2Achim D. Herrmann (LSU: Louisiana State University)H-Index: 13
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#1Amy J. Mallozzi (LSU: Louisiana State University)H-Index: 1
#2Reagan M. Errera (LSU: Louisiana State University)H-Index: 1
Last.Achim D. Herrmann (LSU: Louisiana State University)H-Index: 13
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Abstract Ocean acidification has the potential to impact the ocean's biogeochemical cycles and food web dynamics, with phytoplankton in the distinctive position to profoundly influence both, as individual phytoplankton species play unique roles in energy flow and element cycling. Previous studies have focused on short-term exposure of monocultures to low pH, but do not reflect the competitive dynamics within natural phytoplankton communities. This study explores the use of experimental microcosm...
2 CitationsSource
#1Xinming ChenH-Index: 3
Last.Ariel D. AnbarH-Index: 57
view all 5 authors...
#1Xinming Chen (ASU: Arizona State University)H-Index: 3
#2Stephen J. Romaniello (ASU: Arizona State University)H-Index: 16
Last.Ariel D. Anbar (ASU: Arizona State University)H-Index: 57
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Abstract Determining whether U isotopes are fractionated during incorporation into biogenic carbonates could help to refine the application of 238 U/ 235 U in CaCO 3 as a robust paleoredox proxy. Recent laboratory experiments have demonstrated that heavy uranium (U) isotopes were preferentially incorporated into abiotic aragonite, with an isotope fractionation of ∼0.10‰ ( 238 U/ 235 U). In contrast, no detectable U isotope fractionation has been observed in most natural primary biogenic carbonat...
3 CitationsSource
#1Achim D. Herrmann (LSU: Louisiana State University)H-Index: 13
#2Gwyneth W. Gordon (ASU: Arizona State University)H-Index: 25
Last.Ariel D. Anbar (ASU: Arizona State University)H-Index: 57
view all 3 authors...
Abstract The uranium (U) isotopic composition (δ 238 U) of limestones is increasingly used to quantitatively track changes in paleoredox conditions of the global ocean. However, many limestones have undergone significant dolomitization during diagenesis. To assess the potential impact of diagenetic changes on the U isotope composition of dolomitized rocks, we examined the uranium isotopic composition of a Jurassic carbonate platform of the Franconian Alb in Southern Germany. This platform underw...
1 CitationsSource
#1Xinming Chen (ASU: Arizona State University)H-Index: 3
#2Stephen J. Romaniello (ASU: Arizona State University)H-Index: 16
Last.Ariel D. AnbarH-Index: 57
view all 6 authors...
Abstract Uranium isotope variations (δ238U) recorded in sedimentary carbonate rocks are a promising new proxy for the extent of oceanic anoxia through geological time. However, the effects of diagenetic alteration on the U isotopic composition in carbonate sediments, which are crucial to understand the accurate reconstruction of marine δ238U, are currently poorly constrained. Here we examine the effects of the aragonite-to-calcite transition in the Pleistocene Key Largo Limestone of South Florid...
13 CitationsSource
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