Rare earth elements and stable isotope geochemistry (δ13C and δ18O) of phosphorite deposits in the Gafsa Basin, Tunisia

Ounis, Anouar; Kocsis, László; Chaabani, Fredj; Pfeifer, Hans-Rudolf

doi:10.1016/j.palaeo.2008.07.005

Cited by 86 publications

(62 citation statements)

References 72 publications

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“…Cal car e ous sand stones are depleted in REE but de tailed N-PAAS pat terns (Fig. 15A, C) did not re cover the REE trend typ i cal of ma rine car bon ate where MREE ac cu mu late (in phos phates) or are en riched by diagenesis (Shields and Webb, 2004;Haley et al, 2004;Ounis et al, 2008;Michalík et al, 2013). The REE-pat tern of beds 37 to 44 can be re garded as a sign of re cy cled sil i cates only (Fig.…”

Section: Provenancementioning

confidence: 98%

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Latest Triassic climate humidification and kaolinite formation (Western Carpathians, Tatric Unit of the Tatra Mts)

Lintnerová¹,

Michalı́k²,

Uhlík³

et al. 2013

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The Tomanová For ma tion, of Rhaetian age, over ly ing the Norian Carpathian Keuper in the Tatra Mts. is built of cy clic parasequences of mudstones and sand stones. Quartz (15 to 70 wt.%), kaolinite (13 to 46 wt.%) and 2:1 Al dioctahedral phyllosilicates (dioct 2:1: mus co vite, illite, illite/smectite: 5 to 39 wt.%) rep re sent the ma jor min eral phase. The kaolinite/dioct 2:1 ra tio de creases up wards in the sec tion (from 4.3 to 0.5) and sig nals vari abil ity in weath er ing/ero sion in ten sity and changing wa ter sa lin ity. Ma jor and trace el e ments (LILE, HSFS, REE) in di cate a uni form source -fel sic rocks lo cated prob a bly in the Vindelician High lands. The sed i men ta tion rate (83 mm/ky) was con trolled by cli mate. Al ter na tion of dry and hu mid pe riods is refered by sed i men tary tex tures and by ma tu rity of quartz (ae olian vs. flu vial grains), and or ganic mat ter con tent and com po si tion (C org and d 13 C org ). Authigenic sid er ite or bethierine doc u ments wet and re duced con di tions in the up per part of the Tomanová For ma tion. The sedimention rate of the ma rine Dudzinec For ma tion at tained 25 mm/ka and the char ac ter of cy cles pre served in the se quence is sim i lar as that of the Tomanová For ma tion (fin ing up wards parasequences). How ever, the dif fer ent clay min er al ogy, the re cy cled char ac ter of the sil i cates, the dif fer ent d 13 C org and el e vated imput of car bon ate detri tus with spe cific C and O iso to pic pat terns doc u ment a dis con ti nu ity in the sec tion. The transgressive char ac ter of the Dudzinec Fm. was de duced from the strati graphic dis tri bu tion and en vi ron men tal char ac ter is tics of the ben thic foraminifera pres ent. Involutinids and spirillinids dom i nate in the lower part, endothyrinids gov ern the mid dle part, and in the up per part nodosariids and Ammodiscus-type micro fauna oc cur. These age-di ag nos tic microfossils in di cate a late Rhaetian age. Sea level rise in the Tatric Zone trig gered by ther mal ex pan sion of the Cen tral At lan tic Rift was grad ual, be ing af fected by in put of ter res trial clastic sed i ment both by fresh wa ter and by wind. The Tatric Tri as sic se quence in the West ern Carpathians helps un der stand ing of the de vel op ment of sed i men ta tion, palaeoclimate (kaolinite weath er ing), and palaeo ge ogra phy of the north ern most Tethyan Do main.

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Section: Provenancementioning

confidence: 98%

“…The spe cific distri bu tion of REE known from ter res trial de pos its and palaeosols may act as an an other in di ca tor of cli mate as well as of sed i mentary con di tions (e.g., Nesbit et al, 1990;Condie,1993;Hannigan and Sholkovitz, 2001;Haley et al, 2004;Shields and Webb, 2004;Ounis et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Latest Triassic climate humidification and kaolinite formation (Western Carpathians, Tatric Unit of the Tatra Mts)

Lintnerová¹,

Michalı́k²,

Uhlík³

et al. 2013

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“…15; Table 1). Fatra Formation limestones are depleted relatively to PAAS but the elements from Sm to Ho (middle -MREE; Ounis et al 2008) relatively increased to 0.5-0.6 content of PAAS. The Eu values reach PAAS level and show positive Eu anomaly.…”

Section: Trace Elements and Reementioning

confidence: 95%

“…The typical seawater REE pattern shows HREE enrichment, often also with negative Ce anomaly (Hannigan & Sholkovitz 2001;Haley et al 2004;Ounis et al 2008). The REE (III) -carbonate ion complexes are the dominant dissolved REE species in seawater: their ability to form carbonate complexes increases from light REE (LREE) to heavy REE (HREE).…”

Section: Ree Distribution During Transgressionmentioning

confidence: 99%

“…However, the REE distribution in sediments could change due to fluctuation of redox and pH condition. Different dissolved species can be introduced or removed from the seawater and cause variation in the water and sediments (Ounis et al 2008;Sheldon & Tabor 2009). The distribution of REE can also indicate weathering process, because their leaching behaviour varies according the regional humidity and increased acidity, as documented in paleosoils (Sheldon & Tabor 2009).…”

Section: Ree Distribution During Transgressionmentioning

confidence: 99%

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Paleoenvironments during the Rhaetian transgression and the colonization history of marine biota in the Fatric Unit (Western Carpathians)

Michalı́k¹,

Lintnerová²,

Wójcik-Tabol³

et al. 2013

Geologica Carpathica

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Abstract:Terminal Triassic environmental changes are characterized by an integrated study of lithology, litho-and cyclostratigraphy, paleontology, mineralogy, geochemistry and rock magnetism in the Tatra Mts. The Carpathian Keuper sequence was deposited in an arid environment with only seasonal rivers, temporal lakes and swamps with scarce vegetation. Combination of a wide range of 18 O values (-0.7 to + 2.7) with negative 13 C values documents dolomite precipitation either from brackish or hypersaline lake water, or its derivation from pore water comparably to the Recent Coorong B-dolostone. Negative 13 C values indicate microbial C productivity. Rhaetian transgressive deposits with restricted Rhaetavicula fauna accumulated in nearshore swamps and lagoons. Associations of foraminifers, bivalves and sharks in the Zliechov Basin were controlled by physical factors. Bivalve mollusc biostromes were repetitively destroyed by storms, and temporary firm bottoms were colonized by oysters and burrowers. Subsequent black shale deposition recorded input of eolian dust. Bottom colonization by pachyodont bivalves, brachiopod and corals started much later, during highstand conditions. Facies evolution also revealed by geochemical data, C and O isotope curves reflect eustatic and climatic changes and help reconstruct the evolution of Rhaetian marine carbonate ramp. The Fatra Formation consists of 100 kyr eccentricity and 40 kyr obliquity cycles; much finer rhythmicity may record monsoonlike climatic fluctuations. Fluvial and eolian events were indicated by analysis of grain size and content of clastic quartz, concentrations of foraminiferal (Agathammina) tests in thin laminae indicates marine ingression events. Magnetic susceptibility (MS) variations reflect the distribution of authigenic and detrital constituents in the sequence. Increasing trend of MS correlates with the regressive Carpathian Keuper sequence and culminates within the bottom part of the Fatra Formation. Decreasing trend of MS is observed upwards the transgressive deposits of the Fatra Formation.

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Late Cretaceous climate simulations with different CO₂ levels and subarctic gateway configurations: A model‐data comparison

et al. 2017

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We investigate the impact of different CO2 levels and different subarctic gateway configurations on the surface temperatures during the latest Cretaceous using the Earth System Model COSMOS. The simulated temperatures are compared with the surface temperature reconstructions based on a recent compilation of the latest Cretaceous proxies. In our numerical experiments, the CO2 level ranges from 1 to 6 times the preindustrial (PI) CO2 level of 280 ppm. On a global scale, the most reasonable match between modeling and proxy data is obtained for the experiments with 3 to 5 × PI CO2 concentrations. However, the simulated low‐ (high‐) latitude temperatures are too high (low) as compared to the proxy data. The moderate CO2 levels scenarios might be more realistic, if we take into account proxy data and the dead zone effect criterion. Furthermore, we test if the model‐data discrepancies can be caused by too simplistic proxy‐data interpretations. This is distinctly seen at high latitudes, where most proxies are biased toward summer temperatures. Additional sensitivity experiments with different ocean gateway configurations and constant CO2 level indicate only minor surface temperatures changes (<~1°C) on a global scale, with higher values (up to ~8°C) on a regional scale. These findings imply that modeled and reconstructed temperature gradients are to a large degree only qualitatively comparable, providing challenges for the interpretation of proxy data and/or model sensitivity. With respect to the latter, our results suggest that an assessment of greenhouse worlds is best constrained by temperatures in the midlatitudes.

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Rare earth elements and stable isotope geochemistry (δ13C and δ18O) of phosphorite deposits in the Gafsa Basin, Tunisia

Cited by 86 publications

References 72 publications

Latest Triassic climate humidification and kaolinite formation (Western Carpathians, Tatric Unit of the Tatra Mts)

Latest Triassic climate humidification and kaolinite formation (Western Carpathians, Tatric Unit of the Tatra Mts)

Paleoenvironments during the Rhaetian transgression and the colonization history of marine biota in the Fatric Unit (Western Carpathians)

Late Cretaceous climate simulations with different CO₂ levels and subarctic gateway configurations: A model‐data comparison

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Rare earth elements and stable isotope geochemistry (δ13C and δ18O) of phosphorite deposits in the Gafsa Basin, Tunisia

Cited by 86 publications

References 72 publications

Latest Triassic climate humidification and kaolinite formation (Western Carpathians, Tatric Unit of the Tatra Mts)

Latest Triassic climate humidification and kaolinite formation (Western Carpathians, Tatric Unit of the Tatra Mts)

Paleoenvironments during the Rhaetian transgression and the colonization history of marine biota in the Fatric Unit (Western Carpathians)

Late Cretaceous climate simulations with different CO2 levels and subarctic gateway configurations: A model‐data comparison

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Late Cretaceous climate simulations with different CO₂ levels and subarctic gateway configurations: A model‐data comparison