Geochemical characteristics of the karst-type bauxites: an example from the Kanirash deposit, NW Iran

Abedini, Ali; Mehr, Masoud Habibi; Khosravi, Maryam; Calagari, Ali Asghar

doi:10.1007/s12517-019-4601-z

Cited by 18 publications

(6 citation statements)

References 69 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Jiujialu Formation, which shows parallel unconformities with the overlying lower Carboniferous limestone/clay rock and the underlying Cambrian or Ordovician dolomite strata, usually comprises a 1–20 m thick bauxite bed (bauxite ore/clay rock) and an underlying 0–6 m thick iron bed (iron ore/iron‐rich clay) (Figure 2). This typical “iron‐bauxite” structure is widespread worldwide, such as the Ghiona bauxite deposit in Greece (Kalaitzidis et al., 2010), the Nurra bauxite deposit in Italy (Mameli et al., 2007), the Kanisheeteh, Kanirash, Shahindezh, Qopi, Darzi‐Vali; Soleiman‐Kandi, Kani‐Zarrineh bauxite deposits in Iran (Abedini, Habibi Mehr, et al., 2019; Abedini et al., 2019a, 2019b; Abedini et al., 2022a, 2022b; Calagari & Abedini, 2007; Khosravi et al., 2017, 2021), and most bauxite deposits in China (e.g., Ling et al., 2017; X. Liu et al., 2017; Yu et al., 2019; Z. Zhang et al., 2013). In central Guizhou, the thickness of the Jiujialu Formation is controlled by the paleo‐karst unconformities, that is, the thickness above the karst depression is greater than that above the highland (Figure 3).…”

Section: Geological Settingmentioning

confidence: 99%

Iron Loss During Continental Weathering in the Early Carboniferous Period Recorded by Karst Bauxites

et al. 2023

View full text Add to dashboard Cite

Significant iron (Fe) loss can occur during continental weathering and efflux to the ocean via runoff, historically affecting global Fe cycling and marine ecosystems. Here, we report extremely low Fe content in early Carboniferous (ca. 340 Ma) bauxites in southwestern China. These bauxites were formed by redeposition of terrestrial soils along the paleo‐continental margin of the western South China Plate in warm climates. The bauxites contain high δ56Fe (−0.17‰ to +1.15‰) values with a negative correlation between Fe2O3 and δ56Fe, indicating that a substantial amount of Fe(III) was reduced to isotopically light dissolved Fe(II) and effuxed to the ocean via reductive dissolution under anoxic conditions. The low Corg content and low FeHR/FeT, Mo/Al, U/Al, and V/Al ratios of bauxite suggest that this reduction process occurred during the pedogenic (continental weathering) rather than the depositional/diagenetic stage of karst bauxite formation. Most of the dissolved Fe(II) were rapidly re‐oxidized to Fe(III) and transported toward the paleo‐continental margin forming iron ores with δ56Fe values around zero (−0.13‰ to +0.16‰). The negative correlation between Al2O3 and Fe2O3 contents in global karst bauxites suggests common Fe loss processes during continental weathering in geological periods favoring karst bauxite formation, such as during the Carboniferous, Permian, and Cretaceous periods and the Cenozoic era. Karst bauxite may thus provide a record of Fe loss during continental weathering and act as an indicator of enhanced Fe flux to oceans.

show abstract

Section: Geological Settingmentioning

confidence: 99%

Iron Loss During Continental Weathering in the Early Carboniferous Period Recorded by Karst Bauxites

et al. 2023

View full text Add to dashboard Cite

show abstract

“…In contrast, under higher oxygen fugacity, Eu 3+ dominates in the aqueous system and requires hard bases such as OH − , SO 4 2− and CO 3 2− (especially OH − ) to precipitate, as a result, negative Eu anomaly can be considered. In addition, Abedini et al (2019) suggested that the strong negative Eu anomaly may be associated with higher O 2 and lower pH of the solutions. Post-Archean Australian Shale (PAAS) =0.61 in the evaluation of Eu anomaly (Eu/Eu*); Post/ Archean upper continental crust (UCC)=0.66 is accepted as the post-Archean upper continental crust (Sinisi, 2018).…”

Section: Discussionmentioning

confidence: 99%

Gemological features of diaspore in sodra—Milas (mugla) region

Kinaci

Öztürk

2023

Front. Earth Sci.

View full text Add to dashboard Cite

Diaspore, is related to bauxite in terms of its formation mechanism. Diaspore is one of the gemstone quality stones used in jewelry and jewelry making. It is possible to come across gemstones in various regions of the world. In our country, there are gemstone deposits in all regions. In these deposits, diaspore crystals are considered very valuable. Within the scope of this study, it was aimed to determine the gemological features of the diaspore formations in Sodra (Milas-Mugla) and its surroundings, as well as to determine other minerals and their formation conditions. Main oxide, trace, and rare earth element analyses were performed on seven collected samples. The classification was made using the Al2O3-SiO2-Fe2O3 triangular variation and it was determined that bauxite samples were in the “ferric bauxite” and “bauxite” areas. SEM imaging and EDS analyzes were performed on the samples and according to this result, it was determined that the samples mainly contained O, Al, and Si. The data obtained as a result of Raman Spectroscopy were matched with the device’s own data library and it was determined that the samples taken from the Sodra region were diaspore. In addition, according to the results of the FTIR analysis performed on the faceted sample taken from the Sodra region, it was seen that the samples were compatible with the reference standards and it was scientifically proven to be a diaspore crystal with gemstone quality. During the field studies carried out in the study area, diaspore crystals were encountered in the Milas-Sodra region, together with chloritoid and muscovite, within the metabauxite formations and in the altered zones close to the metabauxite limestone contact. Rock were classified as “muscovitequartzschist,” “quartzschist” with grano-lepidoblastic texture, “micaquartzschist” with lepidoblastic texture, “phyllite” with lepidoblastic texture, and “chlorite-epidote fels” with nematoblastic texture as a result of petrographic analyzes performed on the country rock samples. It is predicted that these gemstone-quality diaspore crystals can be evaluated economically.

show abstract

“…Furthermore, the high field strength elements (e.g., Nb, Zr) and TiO 2 are indicative of magmatic origin due to their immobile behavior during diagenesis and weathering (Berry, 1999;He et al, 2014;Hong et al, 2019Hong et al, , 2020. The Al 2 O 3 /TiO 2 ratio is generally considered a useful indicator of the provenance because the concentrations of Al and Ti in the materials remain constant during diagenesis and weathering (Nesbitt and Young, 1982;Sugitani, 1996;Abedini and Calagari, 2012;Abedini, 2017;Abedini and Calagari, 2017;Abedini et al, 2018;Abedini et al, 2019a;Abedini et al, 2019b;Abedini et al, 2020a;Abedini et al, 2020b;Kiaeshkevarian et al, 2020;Leontopoulou et al, 2021;Abedini and Khosravi, 2022). According to the classification model, the volcanic ashes corresponding to the bentonite deposits are classified as felsic magmas in all sections and in the fields of rhyolite (Figure 5).…”

Section: The Formation Process Of F-rich Bentonitesmentioning

confidence: 99%

Fluorine speciation and origin of Early-Middle Triassic bentonite deposits in Sichuan Basin, South China

Lin

Zheng²,

Zhang³

et al. 2023

Front. Earth Sci.

View full text Add to dashboard Cite

Fluorine (F) is one of the most important environmentally harmful elements released by volcanic activity, and the bentonite deposits that formed from volcanic ashes are potentially harmful to the environment. However, the mechanisms governing F-rich bentonite formation and its F speciation composition remain enigmatic. The F-rich bentonite deposits are widely distributed in the Early-Middle Strata of the Sichuan Basin, South China. Detailed mineralogical and geochemical studies were conducted on the bentonite deposits from five sections of the Sichuan Basin. X-ray diffraction (XRD) analyses indicate that the F-rich bentonites mainly contain quartz, carbonates (calcite and dolomite) or gypsum, and clay minerals, while the clay minerals are dominated by illite and illite/smectite (I/S). Clay mineralogical studies suggest that bentonites were transformed from volcanic ashes during diagenesis by smectite illitization. The major and trace element distribution in F-rich bentonite deposits altered from volcanic ashes is most likely derived from felsic magmas, and alteration of the parent rocks (e.g., rhyolites) to bentonite is associated with leaching and subsequent removal of F. The total fluorine content (FTOT) of the bentonite samples ranged from 1,162 mg/kg to 2,604 mg/kg (average = 1773 mg/kg), well above the average FTOT contents of soils in the world. The results of the sequential extraction experiments show that the highest content is residual-fluorine (Fres), followed by carbonate-fluorine (Fcar) with a mean value of 1,556 mg/kg and 186 mg/kg, indicating carbonate is an important F sink in bentonite deposits. The average fluorine value of organic fluorine (For), Fe/Mn oxide-fluorine (Ffm) and exchangeable fluorine (Fex) are relatively low with an average value of 17.5 mg/kg, 6.8 mg/kg and 4.1 mg/kg, respectively. However, water-soluble fluorine (Fws) has a mean value of 4.0 mg/kg, which is higher than the corresponding average value in soils in an area susceptible to endemic fluorosis in China. Based on the characteristic of fluorine speciation, the fluorine in bentonite deposits may pose a risk to the environment. This study makes an important contribution to a better understanding of the characteristic of fluorine speciation in bentonites and the formation mechanism that governs fluorine enrichment in bentonites.

show abstract

Geochemical characteristics of the karst-type bauxites: an example from the Kanirash deposit, NW Iran

Cited by 18 publications

References 69 publications

Iron Loss During Continental Weathering in the Early Carboniferous Period Recorded by Karst Bauxites

Iron Loss During Continental Weathering in the Early Carboniferous Period Recorded by Karst Bauxites

Gemological features of diaspore in sodra—Milas (mugla) region

Fluorine speciation and origin of Early-Middle Triassic bentonite deposits in Sichuan Basin, South China

Contact Info

Product

Resources

About