Textural and compositional evidence for the evolution of pedogenic calcite and dolomite in a weathering profile on the Kohala Peninsula, Hawai’i

Whipkey, Charles E.; Hayob, Jodie L.

doi:10.1007/bf03176156

Cited by 7 publications

(2 citation statements)

References 34 publications

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“…For disordered, Ca-rich dolomite to form, Folk and Land [1975] proposed that an Mg/Ca ratio >1 is required, but others have suggested that values as high as 3.31 are required [Hardie, 1987]. In Hawaiian soil, dolomite develops on basalt and precipitates when the Mg/Ca ratio of its soil solution is $1 [Capo et al, 2000;Whipkey and Hayob, 2008;Whipkey et al, 2002]. Stream flux on central CLP has a Mg/Ca ratio of 2.34 and the largest river on CLP, the Yellow River has an Mg/Ca ratio of $0.85 Zhang et al, 1995].…”

Section: Formation Of Red Clay Protodolomitementioning

confidence: 99%

Distribution and origin of protodolomite from the late Miocene‐Pliocene Red Clay Formation, Chinese Loess Plateau

He¹,

Chen²,

Balsam³

et al. 2012

Geochem Geophys Geosyst

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[1] The Pliocene epoch is considered the most recent analog of modern warming because CO 2 levels were similar to the present. To explore the carbonate minerals formed in the warmer Pliocene epoch, we studied two continuous sections of the Red Clay Formation on the Chinese Loess Plateau (CLP) by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Stable Isotope Mass Spectrometry. The Red Clay Formation on the CLP exhibits diagnostic FTIR absorption features of calcite and protodolomite. This allowed quantification of the two carbonate minerals by the FTIR method. Using the FTIR method we estimate the average concentration of protodolomite in Bajiazui is 3.6% whereas the Duanjiapo section is 6.0%. Protodolomite occurrence is more consistent and the concentration is higher from $6.5-4.2 Ma B.P. and decreases markedly from 4.2-2.6 Ma B.P. Red Clay protodolomite is depleted in both d 13 C PDB and d 18 O PDB , ranging from À4.1‰ to À10.4 and from À6.7‰ to À11.6, respectively, and has a slightly higher d18 O value than the calcites. SEM observations show that Red Clay protodolomite is composed of euhedral rhombic crystals that range from 1-20 mm in diameter, grow into the soil voids and coexist with authigenic calcite and palygorskite. These observations imply that the protodolomite grew in situ and is authigenic from pedogenesis. Dolomitization in the Red Clay sequence appears to be the result of overcoming kinetic barriers. We propose that in the Red Clay a warm climate with seasonal dry conditions leads to the formation of calcrete from soil pore waters thereby enriching the pore solutions with respect to Mg 2+ and significantly increasing the Mg/Ca ratio bringing about the formation of protodolomite.Components: 9100 words, 7 figures, 8 tables.

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Section: Formation Of Red Clay Protodolomitementioning

confidence: 99%

Distribution and origin of protodolomite from the late Miocene‐Pliocene Red Clay Formation, Chinese Loess Plateau

He¹,

Chen²,

Balsam³

et al. 2012

Geochem Geophys Geosyst

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“…The setting of formation of these dolomite-rich calcretes is different of those commonly described as a result of the evolution of groundwater to reach evaporitic conditions in terminal basin settings (Colson and Cojan, 1996;Jutras et al, 2011;Jutras, 2017) or as a result of the emerging groundwater also under evaporitic conditions (Mather et al, 2019). The scarce spheroidal dolomite found mostly cementing voids of the volcanic fragments is probably the first dolomite phase formed, as in Mirador del Rio profile in Lanzarote, where the initial weathering of the basalts could produce locally enriched Mg-solutions favoring dolomite formation (Capo et al, 2000;Whipkey et al, 2002;Whipkey and Hayob, 2008) as a cement (Alonso-Zarza et al, 2016).…”

Section: Calcrete Profiles Interpretationmentioning

confidence: 76%

Unravelling calcrete environmental controls in volcanic islands, Gran Canaria Island, Spain

Alonso-Zarza

Rodríguez‐Berriguete

Martín-Pérez

et al. 2020

Palaeogeography, Palaeoclimatology, Palaeoecology

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Volcanic islands are unique contexts to analyze the controls on calcrete development in settings with varied relief, climate and vegetation, and lacking carbonate host rocks. This paper discusses the formation of Quaternary calcrete profiles in Gran Canaria volcanic Island, under direct influence of the SAL (Saharian Air Layer). Calcrete profiles are multi-storey and composed of prismatic, massive, laminar, pisolithic, ooid-bearing, sandy mudstones with rhizoliths and brecciated horizons. Host rocks include basalts, siliceous mudstones, volcanic sands and gravels and bioclastic-rich sands. Carbonate is mostly calcite but some dolomite occurs in massive horizons. The main microfabrics include laminated micrite, fine crystalline dolomite, desiccated micrite, micrite-clay groundmass, oriented Mg-rich clays, peloids, spherulites and coated grains. δ 13 C varies from −3.26 to −9.18‰ VPDB and δ 18 O from +0.86 to −3.24‰ VPDB. The 87 Sr/ 86 Sr ratios are between 0.707504 and 0.708860, indicating that calcium was mostly supplied from the CaCO 3-rich aeolian dust coming from the Sahara Desert. Calcrete profiles are mostly pedogenic with roots and microorganisms enabling carbonate precipitation within the soils. The correlation trend of δ 13 C and δ 18 O points to a climate control on precipitation, with the heavier isotope values in the horizons containing dolomite. Sedimentation rates interplayed with calcrete formation processes and erosion to outline the profiles/horizons. Amalgamated laminar horizons formed when the rate of calcrete formation was higher than sedimentation and erosion, whereas areas or periods with relatively higher sedimentation allowed the separation of calcrete horizons. The direction of the winds supplying aeolian dust, and the varied relief, vegetation and climate favored better development of calcretes in the relatively arid and lowland areas of the eastern side of the island. Our study shows that calcretes contain the record of the paleoenvironmental controls that operated in volcanic islands with no previous carbonate substrates.

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Isotopic evidence for dolomite formation in soils

2013

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Textural and compositional evidence for the evolution of pedogenic calcite and dolomite in a weathering profile on the Kohala Peninsula, Hawai’i

Cited by 7 publications

References 34 publications

Distribution and origin of protodolomite from the late Miocene‐Pliocene Red Clay Formation, Chinese Loess Plateau

Distribution and origin of protodolomite from the late Miocene‐Pliocene Red Clay Formation, Chinese Loess Plateau

Unravelling calcrete environmental controls in volcanic islands, Gran Canaria Island, Spain

Isotopic evidence for dolomite formation in soils

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