Organic fluxes and early diagenesis in the lacustrine environment: the superficial sediments of the Lac du Bouchet (Haute Loire, France)

2008 ◽  
pp. 145-156 ◽  
Author(s):  
Andrew J. Patience ◽  
Elisabeth Lallier-Vergès ◽  
Abdelfettah Sifeddine ◽  
Patrick Albéric ◽  
Bernard Guillet
Keyword(s):  
Early Diagenesis ◽  
Lacustrine Environment ◽  
Superficial Sediments

TRANSFORMATIONS OF HIGH-CHARGED SWELLING MINERALS DURING EARLY DIAGENESIS IN RECENT SEDIMENTS OF GDANSK BAY (BALTIC SEA)

2019 ◽  
Author(s):  
Marta Kisiel ◽  
◽  
Michal Skiba ◽  
Artur Kuligiewicz ◽  
Magdalena Skoneczna ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Early Diagenesis ◽  
Recent Sediments

scholarly journals The fate of a travertine record: impact of early diagenesis on the Y‐10 core (Mammoth Hot Springs, Yellowstone National Park, USA)

2021 ◽  
Author(s):  
Eva De Boever ◽  
David Jaramillo‐Vogel ◽  
Anne‐Sophie Bouvier ◽  
Norbert Frank ◽  
Andrea Schröder‐Ritzrau ◽  
...  
Keyword(s):  
Yellowstone National Park ◽  
National Park ◽  
Hot Springs ◽  
Early Diagenesis

scholarly journals Syngenetic rapid growth of ellipsoidal silica concretions with bitumen cores

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hidekazu Yoshida ◽  
Ryusei Kuma ◽  
Hitoshi Hasegawa ◽  
Nagayoshi Katsuta ◽  
Sin-iti Sirono ◽  
...  
Keyword(s):  
Organic Matter ◽  
Early Diagenesis ◽  
Ph Change ◽  
Carbon Preference Index ◽  
Diffusion Growth ◽  
Silica Precipitation ◽  
Precipitated Silica ◽  
Preference Index ◽  
Decomposition Of Organic Matter ◽  
Growth Diagram

AbstractIsolated silica concretions in calcareous sediments have unique shapes and distinct sharp boundaries and are considered to form by diagenesis of biogenic siliceous grains. However, the details and rates of syngenetic formation of these spherical concretions are still not fully clear. Here we present a model for concretion growth by diffusion, with chemical buffering involving decomposition of organic matter leading to a pH change in the pore-water and preservation of residual bitumen cores in the concretions. The model is compatible with some pervasive silica precipitation. Based on the observed elemental distributions, C, N, S, bulk carbon isotope and carbon preference index (CPI) measurements of the silica-enriched concretions, bitumen cores and surrounding calcareous rocks, the rate of diffusive concretion growth during early diagenesis is shown using a diffusion-growth diagram. This approach reveals that ellipsoidal SiO2 concretions with a diameter of a few cm formed rapidly and the precipitated silica preserved the bitumen cores. Our work provides a generalized chemical buffering model involving organic matter that can explain the rapid syngenetic growth of other types of silica accumulation in calcareous sediments.

scholarly journals Macro- and Micronutrient Cycling and Crucial Linkages to Geochemical Processes in Mangrove Ecosystems

2021 ◽  
Vol 9 (5) ◽  
pp. 456
Author(s):  
Daniel M. Alongi
Keyword(s):  
Transformation Process ◽  
Early Diagenesis ◽  
P Availability ◽  
Geochemical Processes ◽  
Nutrient Cycles ◽  
Physiological Mechanisms ◽  
Retention Efficiency ◽  
Mangrove Ecosystems ◽  
N Metabolism ◽  
Transformation Processes

High mangrove productivity is sustained by rapid utilization, high retention efficiency and maximum storage of nutrients in leaves, roots, and soils. Rapid microbial transformations and high mineralization efficiencies in tandem with physiological mechanisms conserve scarce nutrients. Macronutrient cycling is interlinked with micronutrient cycling; all nutrient cycles are linked closely to geochemical transformation processes. Mangroves can be N-, P-, Fe-, and Cu-limited; additions of Zn and Mo stimulate early growth until levels above pristine porewater concentrations induce toxicity. Limited nutrient availability is caused by sorption and retention onto iron oxides, clays, and sulfide minerals. Little N is exported as immobilization is the largest transformation process. Mn and S affect N metabolism and photosynthesis via early diagenesis and P availability is coupled to Fe-S redox oscillations. Fe is involved in nitrification, denitrification and anammox, and Mo is involved in NO3− reduction and N2-fixation. Soil Mg, K, Mn, Zn and Ni pool sizes decrease as mangrove primary productivity increases, suggesting increasing uptake and more rapid turnover than in less productive forests. Mangroves may be major contributors to oceanic Mn and Mo cycles, delivering 7.4–12.1 Gmol Mn a−1 to the ocean, which is greater than global riverine input. The global Mo import rate by mangroves corresponds to 15–120% of Mo supply to the oceanic Mo budget.

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