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Chemical and Isotopic Signatures of Sediments: What do they tell...
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Chemical and Isotopic Signatures of Sediments: What do they tell us about the geological history of the Earth?

A special issue of Geosciences (ISSN 2076-3263). This special issue belongs to the section "Geochemistry".

Deadline for manuscript submissions: closed (31 January 2020) | Viewed by 30906

Special Issue Editor

Dr. Marion Garçon

E-Mail Website
Guest Editor
1. CNRS, LMV Clermont-Ferrand (Laboratoire Magmas et Volcans), Université Clermont Auvergne, 6 Avenue Blaise Pascal, TSA 60026, 63178 Aubiere CEDEX, France
2. Department of Earth Sciences, Institute of Geochemistry and Petrology, ETH Zürich, Clausiusstrasse 25, 8092 Zürich, Switzerland
Interests: geochemistry; isotopes; sediment; continental crust; Archean

Special Issue Information

Dear Colleagues,

Sediments that derived from the weathering of rocks exposed at the surface of the Earth or the precipitation of dissolved constituents out of river or seawater constitute a substantial archive to study the nature, composition, and evolution of the Earth’s major reservoirs, such as the continental crust and the ocean. The creation, transport, preservation, and alteration of sediments are related to geological processes acting in the Earth throughout its history. Their isotopic and chemical compositions are key in helping constrain:

  • Crustal compositions and mechanisms involved in the formation and recycling of crustal material through time
  • Modern and past biogeochemical cycles in the ocean and on continent
  • Environmental and climatic conditions (redox, temperature, biological activity, etc.) prevailing through Earth’s history

This special issue of Geosciences seeks original contributions that provide new insights into the evolution of the Earth’s major reservoirs using the geochemistry of modern and ancient sediments from detrital, chemical, or biochemical origin.

Dr. Marion Garçon
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Geosciences is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Sediment
  • Continental crust
  • Ocean
  • Geochemistry
  • Isotopic compositions
  • Trace elements
  • Early Earth

Published Papers (6 papers)

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Research

21 pages, 6742 KiB  
Article
Multiple Sulfur Isotope Records of the 3.22 Ga Moodies Group, Barberton Greenstone Belt
by Masafumi Saitoh, Sami Nabhan, Christophe Thomazo, Nicolas Olivier, Jean-François Moyen, Yuichiro Ueno and Johanna Marin-Carbonne
Geosciences 2020, 10(4), 145; https://doi.org/10.3390/geosciences10040145 - 16 Apr 2020
Cited by 7 | Viewed by 4163
Abstract
The Moodies Group, the uppermost unit in the Barberton Greenstone Belt (BGB) in South Africa, is a ~3.7-km-thick coarse clastic succession accumulated on terrestrial-to-shallow marine settings at around 3.22 Ga. The multiple sulfur isotopic composition of pyrite of Moodies intervals was newly obtained [...] Read more.
The Moodies Group, the uppermost unit in the Barberton Greenstone Belt (BGB) in South Africa, is a ~3.7-km-thick coarse clastic succession accumulated on terrestrial-to-shallow marine settings at around 3.22 Ga. The multiple sulfur isotopic composition of pyrite of Moodies intervals was newly obtained to examine the influence of these depositional settings on the sulfur isotope record. Conglomerate and sandstone rocks were collected from three synclines north of the Inyoka Fault of the central BGB, namely, the Eureka, Dycedale, and Saddleback synclines. The sulfur isotopic composition of pyrite was analyzed by Secondary Ion Mass Spectrometry (SIMS) for 6 samples from the three synclines and by Isotope Ratio Mass Spectrometry (IR-MS) for 17 samples from a stratigraphic section in the Saddleback Syncline. The present results show a signal of mass-independent fractionation of sulfur isotopes (S-MIF), although t-tests statistically demonstrated that the Moodies S-MIF signals (mostly 0‰ < ∆33S < +0.5‰) are significantly small compared to the signal of the older Paleoarchean (3.6–3.2 Ga) records. These peculiar signatures might be related to initial deposition of detrital pyrite of juvenile origin from the surrounding intrusive (tonalite–trondhjemite–granodiorite; TTG) and felsic volcanic rocks, and/or to secondary addition of hydrothermal sulfur during late metasomatism. Moreover, fast accumulation (~0.1–1 mm/year) of the Moodies sediments might have led to a reduced accumulation of sulfur derived from an atmospheric source during their deposition. As a result, the sulfur isotopic composition of the sediments may have become susceptible to the secondary addition of metasomatic sulfur on a mass balance point of view. The sulfur isotopic composition of Moodies pyrite is similar to the composition of sulfides from nearby gold mines. It suggests that, after the Moodies deposition, metasomatic pyrite formation commonly occurred north of the Inyoka Fault in the central BGB at 3.1–3.0 Ga. Full article
(This article belongs to the Special Issue Chemical and Isotopic Signatures of Sediments: What do they tell us about the geological history of the Earth?)
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14 pages, 2653 KiB  
Article
Geochemical Discrimination of Monazite Source Rock Based on Machine Learning Techniques and Multinomial Logistic Regression Analysis
by Keita Itano, Kenta Ueki, Tsuyoshi Iizuka and Tatsu Kuwatani
Geosciences 2020, 10(2), 63; https://doi.org/10.3390/geosciences10020063 - 6 Feb 2020
Cited by 34 | Viewed by 5397
Abstract
Detrital monazite geochronology has been used in provenance studies. However, there are complexities in the interpretation of age spectra due to their wide occurrence in both igneous and metamorphic rocks. We use the multinomial logistic regression (MLR) and cross-validation (CV) techniques to establish [...] Read more.
Detrital monazite geochronology has been used in provenance studies. However, there are complexities in the interpretation of age spectra due to their wide occurrence in both igneous and metamorphic rocks. We use the multinomial logistic regression (MLR) and cross-validation (CV) techniques to establish a geochemical discrimination of monazite source rocks. The elemental abundance-based geochemical discrimination was tested by selecting 16 elements from granitic and metamorphic rocks. The MLR technique revealed that light rare earth elements (REEs), Eu, and some heavy REEs are important discriminators that reflect elemental fractionation during magmatism and/or metamorphism. The best model yielded a discrimination rate of ~97%, and the CV method validated this approach. We applied the discrimination model to detrital monazites from African rivers. The detrital monazites were mostly classified as granitic and of garnet-bearing metamorphic origins; however, their proportion of metamorphic origin was smaller than the proportion that was obtained by using the elemental-ratio-based discrimination proposed by Itano et al. in Chemical Geology (2018). Considering the occurrence of metamorphic rocks in the hinterlands and the different age spectra between monazite and zircon in the same rivers, a ratio-based discrimination would be more reliable. Nevertheless, our study demonstrates the advantages of machine-learning-based approaches for the quantitative discrimination of monazite. Full article
(This article belongs to the Special Issue Chemical and Isotopic Signatures of Sediments: What do they tell us about the geological history of the Earth?)
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27 pages, 2666 KiB  
Article
Trace Metal and Cd Isotope Systematics of the Basal Datangpo Formation, Yangtze Platform (South China) Indicate Restrained (Bio)Geochemical Metal Cycling in Cryogenian Seawater
by Simon V. Hohl, Shao-Yong Jiang, Sebastian Viehmann, Wei Wei, Qian Liu, Hai-Zhen Wei and Stephen J.G. Galer
Geosciences 2020, 10(1), 36; https://doi.org/10.3390/geosciences10010036 - 19 Jan 2020
Cited by 19 | Viewed by 4786
Abstract
The behaviour of bioavailable trace metals and their stable isotopes in the modern oceans is controlled by uptake into phototrophic organisms and adsorption on and incorporation into marine authigenic minerals. Among other bioessential metals, Cd and its stable isotopes have recently been used [...] Read more.
The behaviour of bioavailable trace metals and their stable isotopes in the modern oceans is controlled by uptake into phototrophic organisms and adsorption on and incorporation into marine authigenic minerals. Among other bioessential metals, Cd and its stable isotopes have recently been used in carbonate lithologies as novel tracer for changes in the paleo primary productivity and (bio)geochemical cycling. However, many marine sediments that were deposited during geologically highly relevant episodes and which, thus, urgently require study for a better understanding of the paleo environment are rather composed of a mixture of organic matter (OM), and detrital and authigenic minerals. In this study, we present Cd concentrations and their isotopic compositions as well as trace metal concentrations from sequential leachates of OM-rich shales of the Cryogenian basal Datangpo Formation, Yangtze Platform (South China). Our study shows variable distribution of conservative and bioavailable trace metals as well as Cd isotope compositions between sequential leachates of carbonate, OM, sulphide, and silicate phases. We show that the Cd isotope compositions obtained from OM leachates can be used to calculate the ambient Cryogenian surface seawater of the restricted Nanhua Basin by applying mass balance calculations. By contrast, early diagenetic Mn carbonates and sulphides incorporated the residual Cd from dissolved organic matter that was in isotopic equilibrium with deep/pore waters of the Nanhua Basin. Our model suggests that the Cd isotopic composition of surface seawater at that time reached values of modern oxygenated surface oceans. However, the deep water Cd isotope composition was substantially heavier than that of modern fully oxygenated oceans and rather resembles deep waters with abundant sulphide precipitation typical for modern oxygen minimum zones. This argues for incomplete recycling of Cd and other bioavailable metals shortly after the Sturtian glaciation in the redox stratified Cryogenian Nanhua Basin. Our study highlights the importance of sequential leaching procedures when dealing with impure authigenic sediments such as OM-rich carbonates, mudstones, or shales to achieve reliable trace metal concentrations and Cd isotope compositions as proxies for (bio)geochemical metal cycling in past aquatic systems. Full article
(This article belongs to the Special Issue Chemical and Isotopic Signatures of Sediments: What do they tell us about the geological history of the Earth?)
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19 pages, 2385 KiB  
Article
Geochemical Signatures of Paleoclimate Changes in the Sediment Cores from the Gloria and Snorri Drifts (Northwest Atlantic) over the Holocene-Mid Pleistocene
by Liudmila L. Demina, Ekaterina A. Novichkova, Alexander P. Lisitzin and Nina V. Kozina
Geosciences 2019, 9(10), 432; https://doi.org/10.3390/geosciences9100432 - 5 Oct 2019
Cited by 10 | Viewed by 5171
Abstract
A multiproxy study of the sediment cores taken from the Snorri Drift, formed under the influence of the Iceland–Scotland bottom contour current, and from the Gloria Drift, located southward Greenland at the boundary of Irminger and Labrador Seas, was performed. This area undergoes [...] Read more.
A multiproxy study of the sediment cores taken from the Snorri Drift, formed under the influence of the Iceland–Scotland bottom contour current, and from the Gloria Drift, located southward Greenland at the boundary of Irminger and Labrador Seas, was performed. This area undergoes a variable mixing of polar waters with the warm North Atlantic current, whose intensity and direction seemed to change dramatically with the alteration of warming and cooling periods during the six marine isotope stages MIS 1-6. The relative age of this core does not exceed 190,000 cal yr BP; the average sedimentation rate was 1.94 and 2.45 cm/kyr in the Gloria and Snorri Drifts core respectively. In both the cores, the sediment records showed the downcore co-variation of ice-rafted debris (IRD); and terrigenous elements, such as Si, Al, Ti, Cr, and Zr, were revealed; their values were clearly higher in the glacial periods (MIS 2, 4, and 6) compared to interglacials (MIS 1, 3, and 5). The downcore rhythmic distributions of these elements, as well as Al/Si, Ti/Al, Fe/Al ratios exhibit an opposite trend with that of δ18O values, biogenic components (CaCO3, BioSiO2), and Si/Fe and Mn/Fe ratios. Full article
(This article belongs to the Special Issue Chemical and Isotopic Signatures of Sediments: What do they tell us about the geological history of the Earth?)
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36 pages, 9683 KiB  
Article
The Sedimentary Origin of Black and White Banded Cherts of the Buck Reef, Barberton, South Africa
by Morgane Ledevin, Nicholas Arndt, Catherine Chauvel, Etienne Jaillard and Alexandre Simionovici
Geosciences 2019, 9(10), 424; https://doi.org/10.3390/geosciences9100424 - 1 Oct 2019
Cited by 14 | Viewed by 6976
Abstract
The Buck Reef is a 250–400 m thick sequence of banded black and white (B&W) cherts deposited ca. 3416 Ma ago in a shallow basin. We provide field, petrological and geochemical constraints on the chert-forming process and the origin of the banding. White [...] Read more.
The Buck Reef is a 250–400 m thick sequence of banded black and white (B&W) cherts deposited ca. 3416 Ma ago in a shallow basin. We provide field, petrological and geochemical constraints on the chert-forming process and the origin of the banding. White layers consist of nearly pure microquartz, while black layers are mixed with detrital carbonaceous matter, quartz grains and carbonaceous microlaminae, interpreted as remnants of microbial mats. The circulation of Si-rich fluid is recorded by abundant chert veins and pervasive silicification. However, the high purity of the white layers, their lack of internal structures and extremely low Al, Ti and high-field-strength elements preclude an origin by silicification of sedimentary or volcanic precursors. Moreover, their reworking at the surface into slab conglomerates, and sediment-like contacts with black layers rule out a diagenetic origin. We propose a new model whereby the white layers were periodically deposited as precipitates of pure silica; and the micro-layering within the black layers formed by annual temperature fluctuations, favouring microbial activity in summer and inorganic silica precipitation in winter. Outcrop-scale alternation of B&W layers was associated with major, thousand-year-long climate events: white cherts represent massive silica precipitation resulting from changes in ocean circulation and temperature during cold intervals. Full article
(This article belongs to the Special Issue Chemical and Isotopic Signatures of Sediments: What do they tell us about the geological history of the Earth?)
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26 pages, 3754 KiB  
Article
Copper and its Isotopes in Organic-Rich Sediments: From the Modern Peru Margin to Archean Shales
by Emily R. Ciscato, Tomaso R. R. Bontognali, Simon W. Poulton and Derek Vance
Geosciences 2019, 9(8), 325; https://doi.org/10.3390/geosciences9080325 - 25 Jul 2019
Cited by 10 | Viewed by 3851
Abstract
The cycling of copper (Cu) and its isotopes in the modern ocean is controlled by the interplay of biology, redox settings, and organic complexation. To help build a robust understanding of Cu cycling in the modern ocean and investigate the potential processes controlling [...] Read more.
The cycling of copper (Cu) and its isotopes in the modern ocean is controlled by the interplay of biology, redox settings, and organic complexation. To help build a robust understanding of Cu cycling in the modern ocean and investigate the potential processes controlling its behavior in the geological past, this study presents Cu abundance and isotope data from modern Peru Margin sediments as well as from a suite of ancient, mostly organic-rich, shales. Analyses of an organic-pyrite fraction extracted from bulk modern sediments suggest that sulphidation is the main control on authigenic Cu enrichments in this setting. This organic-pyrite fraction contains, in most cases, >50% of the bulk Cu reservoir. This is in contrast to ancient samples, for which a hydrogen fluoride (HF)-dissolvable fraction dominates the total Cu reservoir. With <20% of Cu found in the organic-pyrite fraction of most ancient sediments, interpretation of the associated Cu isotope composition is challenging, as primary signatures may be masked by secondary processes. But the Cu isotope composition of the organic-pyrite fraction in ancient sediments hints at the potential importance of a significant Cu(I) reservoir in ancient seawater, perhaps suggesting that the ancient ocean was characterized by different redox conditions and a different Cu isotope composition to that of the modern ocean. Full article
(This article belongs to the Special Issue Chemical and Isotopic Signatures of Sediments: What do they tell us about the geological history of the Earth?)
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