Aridic crusts and vein mineralisations in the playa Areg el Makrzene, South Tunisia

Fromm, Roman; Hachicha, Tarek; Smykatz-Kloss, Werner

doi:10.1016/j.chemer.2005.01.005

Cited by 6 publications

(2 citation statements)

References 22 publications

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“…The crusts are enriched in As, Co, Ni, and Sb, while the rare-earth element (REE) content is close to the hydrogenic modern Fe crusts [122,123]. These crusts present a positive anomaly in Ce (Ce/Ce* = 6.31 average) ( Figure 7).…”

Section: Mineralogy and Geochemistrymentioning

confidence: 98%

Jurassic Non-Carbonate Microbialites from the Betic-Rifian Cordillera (Tethys Western End): Textures, Mineralogy, and Environmental Reconstruction

Reolid

Abad

2019

Minerals

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The term microbialite is commonly applied for describing carbonate organo-sedimentary deposits that have accreted as a result of the activity of benthic microbial communities (BMC). However, non-carbonate microbialites are progressively well-known and show a great diversity of organisms, processes, and mineralogical compositions. This article reviews three types of Jurassic microbialites from four different environmental contexts from the Betic-Rifian Cordillera (South Spain and North Morocco): marine hardgrounds, submarine caves, hydrothermal vents, and submarine volcanic deposits. The Middle-Late Jurassic transition in the External Subbetic (Betic Cordillera) and the Jbel Moussa Group (Rifian Calcareous Chain) was characterized by the fragmentation of the carbonate epicontinental platforms that favored these different settings: (A) Many stratigraphic breaks are recorded as hardgrounds with surficial hydrogenetic Fe crusts and macro-oncoids related to chemo-organotrophic behavior of BMC that served as a specific trap for Fe and Mn enrichment; (B) Cryptic hydrogenetic Fe-Mn crusts (or endostromatolites) grew in the walls of submarine cavities and fractures mainly constituted by Frutexites (chemosynthetic and cryptobiontic microorganism) locally associated to serpulids; (C) Hydrothermal Mn crusts are mainly constituted by different types of filaments and bacillus-shaped bacteria, whose mineralogy and geochemistry point to a submarine hydrothermal origin; (D) Finally, glauconite laminated crusts, constituted by branched cylindrical filaments, have grown in cryptic spaces among the pillow-lava bodies, probably related to the metabolism of chemo-organotrophic microbes under oxic conditions at temperatures between 30 and 90 °C. In most of the cases described in this work, microbial organisms forming microbialites were extremophiles.

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Section: Mineralogy and Geochemistrymentioning

confidence: 98%

Jurassic Non-Carbonate Microbialites from the Betic-Rifian Cordillera (Tethys Western End): Textures, Mineralogy, and Environmental Reconstruction

Reolid

Abad

2019

Minerals

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“…Similarly, Roy and Smykatz-Kloss (2007) studied the REE geochemistry of evaporites and the degree of roundness of rock fragments in the clastic fractions of sediments in order to reconstruct the palaeo-fluvial conditions in the Thar Desert. Fromm et al (2005) used Fe-Mn vein mineralisations and the different stages of calcrete formation as indicators of the development of the Tunisian desert. Roy et al (2009Roy et al ( , 2010 used geochemical signatures of chemical weathering and mineralogical composition of playa lake sediments to reconstruct late Holocene hydrological changes at the margins of the Thar Desert (India) and late Pleistocene-Holocene palaeo-environmental conditions at Sonora Desert (Mexico).…”

Section: Geochemical Criteriamentioning

confidence: 99%

Evaporite mineralogy and major element geochemistry as tools for palaeoclimatic investigations in arid regions: A synthesis

Smykatz-Kloss¹,

Roy²

2010

BSGM

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This paper presents a synthesis of the applications of evaporite mineralogy and the relationship between major elements for the palaeoclimatological research of arid regions, with examples from Playa Oum el Krialate in Tunisia, Wadi Natron in Egypt, East African Rift Valley, etc. The numerous evaporite minerals serving as indicators of palaeo-drylands (salinity and evaporation) include carbonates, sulfates, and Na, K, Ca, and Mg chlorides. The occurrence of double salts, such as glauberite, carnallite, kainite, gaylussite, pirssonite, burkeite, etc., suggests disequilibrium conditions. Apart from that, the presence of very rare Fe-sulfates, such as rozenite and szomolnokite, indicates anoxic conditions with higher salinity. The formation of Na-silicates, such as magadiite and kenyaite, implies a decrease in pH of a highly alkaline Na concentrated brine. The Mg-silicates (palygorskite, Mg-montmorillonite and talc) form quickly and then re-dissolve when conditions change. Identification of fulgurites in the Sahara has been related to palaeo-lightning. We have also discussed a simple geochemical approach of using the ratios of soluble/insoluble elements to identify palaeo-arid events with examples from loess-soil sequences from Feiran Oasis in the Sinai Desert (Egypt) and salty silt lacustrine sequences from Thar Desert (India).

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Hydrogeochemical and isotopic characteristics of emerging springs in southeastern Tunisia

Essamin

Kamel

2022

Environ Earth Sci

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Aridic crusts and vein mineralisations in the playa Areg el Makrzene, South Tunisia

Cited by 6 publications

References 22 publications

Jurassic Non-Carbonate Microbialites from the Betic-Rifian Cordillera (Tethys Western End): Textures, Mineralogy, and Environmental Reconstruction

Jurassic Non-Carbonate Microbialites from the Betic-Rifian Cordillera (Tethys Western End): Textures, Mineralogy, and Environmental Reconstruction

Evaporite mineralogy and major element geochemistry as tools for palaeoclimatic investigations in arid regions: A synthesis

Hydrogeochemical and isotopic characteristics of emerging springs in southeastern Tunisia

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