Abstract. 

"The timing and causation of the Capitanian (late Middle Permian) biocrisis remain controversial. Here, a detailed uranium-isotopic (δ238U) profile was generated for the mid-Capitanian to lower Wuchiapingian of the Penglaitan section (the Guadalupian/Lopingian Permian global stratotype) in South China for the purpose of investigating relationships between the biocrisis and coeval oceanic anoxic events (OAEs). Negative δ238U excursions indicate two distinct OAEs, a mid-Capitanian (OAE-C1) and an end-Capitanian (OAE-C2) event. [...]".

Source: Science Direct
Authors: Huyue Song et al.
DOI: https://doi.org/10.1016/j.epsl.2023.118128

Read the full article here.

Abstract. 

"Ocean anoxia was one of the key killing mechanisms responsible for the end-Permian mass extinction (∼252 Ma). However, the temporal evolution and the triggering mechanisms of the end-Permian anoxia are controversial, with the current view being that the water column deoxygenation was a spatially and temporally heterogeneous event. Here, we use cerium-anomalies, uranium contents and rare earth element and yttrium (REY) compositions measured on the carbonate fraction of samples from two marine sections in Armenia and South China to constrain the evolution of end-Permian marine anoxia. [...]". 

Source: Science Direct
Authors: Johann Müller et al.
DOI: https://doi.org/10.1016/j.gloplacha.2023.104067 

Read the full article here.

Abstract. 

"The Rare Earth Element (REE) systematics of the post-Marinoan cap dolostones reflect the marine redox conditions and chemistry in the immediate aftermath of the snowball Earth. Rare earth elements and yttrium (REY) compositions in the Doushantuo cap dolostones that directly overlie Nantuo glacial diamictites in south China are determined from the inner shelf to the slope. In general, shale-normalized REY patterns (REYSN) of the cap dolostones show significant fractionations that are characterized by light REE depletion, slight middle REE enrichment relative to the light and heavy REEs, positive Eu anomalies, and slightly super-chondritic Y/Ho ratios. [...]".

Source: Science Direct
Authors: Min Ren & Ruifan Li
DOI: https://doi.org/10.1016/j.sedgeo.2023.106343

Read the full article here.

Abstract. 

"Deep water freshening beneath pan-Arctic ice shelves has recently been proposed based on the absence of excess thorium in glacial Arctic sediments. This profound proposal requires scrutiny of Arctic paleohydrology during past glacial periods. Here, we present structural and geochemical results of inorganic authigenic carbonates in deep-sea glacimarine sediments from the Mendeleev Ridge, western Arctic Ocean over the last 76 kyr. Our results suggest that Polar Deep Water in the western Arctic became brackish and anoxic during stadial periods. We argue that sediment-laden hyperpycnal meltwater discharged from paleo-ice sheets filled much of the water column [...]".

Source: Nature 
Authors: Kwangchul Jang et al.
DOI: https://doi.org/10.1038/s43247-023-00708-6

Read the full article here.

Abstract. 

"Despite carbon-cycle perturbations at a global scale during the early Toarcian, the extent of anoxia during the ∼182-Ma Toarcian Oceanic Anoxic Event (T-OAE) remains in debate. A common factor in the development of oceanic anoxia is watermass restriction, which is thought to have been important in the NW European Seaway, but whose influence elsewhere is relatively unstudied. Here, we analyze Mo/TOC (a proxy for watermass restriction) and redox proxies (e.g., Corg/P) in two sections of the Asturian Basin (northern Iberian Paleomargin), and we integrate these results with data from a suite of global Toarcian sections in order to reassess [...]".

Source: Science Direct 
Authors: Javier Fernández-Martínez et al.
DOI: https://doi.org/10.1016/j.gloplacha.2022.104026

Read the full article here.

Abstract.

"Before the Quaternary, the Earth experienced a series of environmental perturbations. The causal links between large volcanic events, extreme climatic change, and ocean anoxia have been examined in the context of these perturbations. However, to date, the correlation between oceanic anoxia and large volcanic activity in the Pleistocene remains poorly constrained. Identifying the physical processes that can control changes to the marine osmium, uranium, and sulfur isotope ratios is critical to understanding how volcanic activity, climate changes, and ocean anoxia have coevolved throughout the Quaternary. [...]".

Source: Science Direct 
Authors: Wenlong Pei et al. 
DOI: https://doi.org/10.1016/j.palaeo.2022.111360

Read the full article here.

Abstract.

"A Tremadocian (Early Ordovician, base Stairsian North American Stage) mass extinction event is recorded globally in rocks from several ancient continents and is accompanied by a globally correlated positive carbon isotope excursion (CIE; the largest during the Early Ordovician). In this study, elemental concentrations and uranium isotope compositions (δ238U) were measured for carbonate samples from three sections (along a proximal-to-distal transect: Ibex area, Shingle Pass, Meiklejohn Peak, respectively) in the Great Basin to test the role of ocean anoxia/euxinia on the base Stairsian mass extinction event. [...]".

Source: Science Direct 
Authors: Xinze Lu et al. 
DOI: https://doi.org/10.1016/j.gca.2022.11.028

Read the full article here.

Abstract. 

"The Great Ordovician Biodiversification Event (GOBE) achieved its peak during the Middle Ordovician, likely in association with climatic cooling and a rise of atmospheric O2. However, unstable redox states developed widely in contemporaneous epeiric seas, challenging previous assumptions about sustained oceanic oxygenation driven by deep-ocean ventilation in the aftermath of Ordovician cooling. Here, we investigate two Middle-Upper Ordovician shale-dominated successions from intra-shelf basin and slope settings of the Yangtze Sea, South China. […]".

Source: Science Direct 
Authors: Junpeng Zhang et al.
DOI: https://doi.org/10.1016/j.epsl.2022.117858

Read the full article here.

Abstract. 

"The Carnian Humid Episode (CHE) represents a dramatic dry to wet climate transition in the Late Triassic. Manifestations of this climate shift and its associated biological and environmental responses are not fully understood. Here, we carried out carbonate carbon isotope, trace metal, and pyrite framboid analyses at Wolonggang in southwest China to trace palaeoenvironmental changes during this critical interval. The CHE at Wolonggang is marked by the development of fine laminated carbonaceous siltstones and black shales overlying the intensely bioturbated Zhuganpo limestone deposited in the latest Julian 1. [...]". 

Source: Science Direct 
Authors: Zaitian Zhang et al.
DOI: https://doi.org/10.1016/j.gloplacha.2022.103942

Read the full article here.

Abstract. 

"The Late Devonian, during which one of the “Big Five” Phanerozoic mass extinction events occurred, was one of the most important time intervals in Earth history. Nevertheless, the paucity of deep-sea records due to subduction has hampered elucidation of the pelagic environment during the Late Devonian in Panthalassa. However, ancient hydrothermal ferromanganese sediments, which were deposited on the abyssal seafloor and then accreted onto continental margins, are preserved as umber deposits and exposed in accretionary prisms. These sediments can provide key information to characterize the paleo-ocean. [...]".

Source: Science Direct 
Authors: Yusuke Kuwahara et al. 
DOI: https://doi.org/10.1016/j.gloplacha.2022.103920

Read the full article here.