Deep sea turbidites in brine-filled anoxic basins of the Mediterranean Ridge. Depositional models based on sedimentological and geochemical characterization

Rimoldi, B; Sironi, Maria

doi:10.1007/bf02967143

Cited by 4 publications

(3 citation statements)

References 22 publications

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“…Furthermore, SEM images provide evidence of fibrous materials, probably related to the presence of a microbial mat/organic fraction in the sediments (Fig. 2h, i), in agreement with results of recent microbiological studies (Ferrer et al, 2012;Stock et al, 2012) and sedimentological investigations (Rimoldi and Cita, 2007 specimens from Thetis and Kryos sequences. In Tyro sediments the amplitude of detritic minerals is lower with respect to other studied sediments (about 40 %), especially in samples from depths of 4-6 cm and 10-11 cm where halides and high-Mg calcite and dolomite are more concentrated.…”

Section: Mineralogysupporting

confidence: 90%

“…This component should have Gd/Gd * ≥ 1, MREE enrichment chondritic or slight higher Y/Ho values and Zr/Hf ratios from chondritic to superchondritic in order to agree with values recognised in studied sediments from Medee and Tyro basins. We suggest that this component is organic matter associated to bacterial colonies recognised during this study and previous investigations (Rimoldi and Cita, 2007). In order to support this hypothesis investigated samples have been depicted according to their Y/Ho vs. Zr/Hf values (Fig.…”

Section: Discussionsupporting

confidence: 79%

“…Bortoluzzi et al (2011) described sediments from the Kryos, Thetis and Medee basins as sandy products underlying to a basal layer of grey mud about 23 cm below the seafloor that they interpreted as turbidites from the flanks of ridges probably fallen as a consequence of tectonic activity. Rimoldi and Cita (2007) investigated sediments from the Tyro basin and recognised a deep sequence of homogeneous green mud, rich in organic matter, that was trigged by seismic events and/or tectonically induced tsunamis. Sample collections of sediments were carried out employing an USGS-modified NEL-box corer (Tranchida et al, 2011).…”

Section: Methodsmentioning

confidence: 99%

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Authigenic phases and biomass contents drive Zr, Hf and REE distributions in anoxic lake sediments

Censi

Saiano

Raso³

2013

Preprint

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REE, Zr and Hf distributions in seafloor sediments collected from the hypersaline, anoxic Thetis, Kryos, Medee and Tyro deep-sea basins from the Eastern Mediterranean were determined in light of their mineralogical composition, and biomass contents. Mineralogical investigations demonstrate that all the studied sediments show a similar mineralogy. Detritic assemblages mainly consist of quartz, gypsum and calcite with Mg contents ranging from 0 to about 7%, often of a bioclastic nature. On the contrary, authigenic parageneses are formed by halite, bischofite, dolomite and calcite, with Mg contents up to 22%. Textural evidences of biological activity were also identified. In sediments from the Medee and Tyro basins, REE, Zr and Hf distributions were analysed in the fraction soluble in nitric acid, whereas in materials coming from the Thetis and Kryos basins, the water-soluble sediment fraction had been previously removed and REE, Zr and Hf distributions were investigated in the residue. This approach evidenced that shale-normalised REE patterns of the whole fraction soluble in nitric acid show strong intermediate REE (MREE) enrichments that give way to positive Gd anomalies once water-soluble minerals are removed. Y/Ho ratios are clustered around chondritic values justified by the occurrence of detritic minerals whereas Zr/Hf values span a~wider range from slightly subchondritic to superchondritic terms. Negative Gd anomalies, subchondritic Y/Ho and Zr/Hf values are found in Mg-carbonate rich samples suggesting that authigenic Mg-carbonates partition Ho and Hf with respect to Y and Zr during their crystallization from brines. Textural observations and biomass analyses highlighted effects of biological activities in sediments involving Zr and Hf enrichments and the highest Zr/Hf values according to the preferential Zr removal onto biological surfaces, without partitioning Y with respect to Ho. These first data suggest that Zr/Hf ratio and REE distributions can represent tracers of biological activity in sediments

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Section: Mineralogysupporting

confidence: 90%

Section: Discussionsupporting

confidence: 79%

Section: Methodsmentioning

confidence: 99%

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Authigenic phases and biomass contents drive Zr, Hf and REE distributions in anoxic lake sediments

Censi

Saiano

Raso³

2013

Preprint

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Sediment geochemistry of the Thetis hypersaline anoxic basin (eastern Mediterranean Sea)

Oliveri

Sprovieri

Manta

et al. 2013

Sedimentary Geology

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Micropalaeontological and Geochemical Evidence of the Late Jurassic Radiolarians Cherts of Naga Ophiolite Hill, Nagaland, Northeast-India

Ayyamperumal¹,

Ramasamy²,

Gopalakrishnan³

et al. 2021

OJG

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We analyzed the radiolarian assemblages (pelagic sediments) and geochemical studies of 15 samples collected from Meluri district Nagaland, Naga Hills Ophiolite belt (NHO) and it consists of the Flysch Naga-Arakan-Yoma trough beyond the Indo-Myanmar border. It reflects one of the many components of the Himalayan Orogenic systems of Tethyan oceanic crust discovered in Nagaland at Meluri district of India and they have very well-preserved studies and can be identified to Upper Jurassic (Kimmeridgian-mid-Tithonian). As well as a continuous sequence of Kimmeridgian-mid-Tithonian, five radiolarian assemblages have been identified in this study. This is so far the first recovery of pelagic sediment assemblages (Radiolarians) from the Naga Hills Ophiolite complex. Samples of Naga Hills Ophiolite belts fell in the Sublitharenite, Litharenite, and Fe-shale Fe-sand area, and the A-CN-K diagram indicates that these sediments in the source region were exposed deep to moderate weathering conditions. In the discriminant plot, the Naga Hill-Ophiolite-Chert samples occupy the field of origin of the sediment quartzose, and the log (K 2 O/Na 2 O) versus SiO 2 samples fall into the active continental marginal

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Deep sea turbidites in brine-filled anoxic basins of the Mediterranean Ridge. Depositional models based on sedimentological and geochemical characterization

Cited by 4 publications

References 22 publications

Authigenic phases and biomass contents drive Zr, Hf and REE distributions in anoxic lake sediments

Authigenic phases and biomass contents drive Zr, Hf and REE distributions in anoxic lake sediments

Sediment geochemistry of the Thetis hypersaline anoxic basin (eastern Mediterranean Sea)

Micropalaeontological and Geochemical Evidence of the Late Jurassic Radiolarians Cherts of Naga Ophiolite Hill, Nagaland, Northeast-India

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