Lateritization and Bauxitization Events

Retallack, Gregory J.

doi:10.2113/gsecongeo.105.3.655

Cited by 142 publications

(122 citation statements)

References 98 publications

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“…For example, many of the lavas of the British Tertiary igneous province, a subprovince of the North Atlantic igneous province LIP of late Paleocene to early Eocene age that was emplaced and remained at mid-paleolatitudes of ∼ 45 • N (Ganerød et al, 2010), were erupted subaerially (Saunders et al, 1997) and are often closely associated with well-developed laterites, such as the 30 m-thick unit belonging to the Interbasaltic Formation in Antrim, Northern Ireland (Hill et al, 2000) and the red boles on the Isles of Mull and Skye in Scotland (Emeleus et al, 1996). Elsewhere in ostensibly temperate Europe, bauxite was named from Les Baux-de-Provence in France (∼ 44 • N) for a lateritic aluminum ore that mainly formed on carbonate rocks of Jurassic and Cretaceous age (Retallack, 2010). In western North America, some of the highest calculated denudation rates for crystalline bedrock for non-glacial times were documented in the Green River Basin (42 • N) and ascribed to enhanced silicate dissolution rates associated with elevated atmospheric pCO 2 levels that occurred during the EECO (Smith et al, 2008).…”

Section: Temperate-latitude Safety Valvesmentioning

confidence: 99%

Modulation of Late Cretaceous and Cenozoic climate by variable drawdown of atmospheric pCO2 from weathering of basaltic provinces on continents drifting through the equatorial humid belt

Kent

Muttoni

2013

Clim. Past

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Abstract. The small reservoir of carbon dioxide in the atmosphere (pCO2) that modulates climate through the greenhouse effect reflects a delicate balance between large fluxes of sources and sinks. The major long-term source of CO2 is global outgassing from sea-floor spreading, subduction, hotspot activity, and metamorphism; the ultimate sink is through weathering of continental silicates and deposition of carbonates. Most carbon cycle models are driven by changes in the source flux scaled to variable rates of ocean floor production, but ocean floor production may not be distinguishable from being steady since 180 Ma. We evaluate potential changes in sources and sinks of CO2 for the past 120 Ma in a paleogeographic context. Our new calculations show that decarbonation of pelagic sediments by Tethyan subduction contributed only modestly to generally high pCO2 levels from the Late Cretaceous until the early Eocene, and thus shutdown of this CO2 source with the collision of India and Asia at the early Eocene climate optimum at around 50 Ma was inadequate to account for the large and prolonged decrease in pCO2 that eventually allowed the growth of significant Antarctic ice sheets by around 34 Ma. Instead, variation in area of continental basalt terranes in the equatorial humid belt (5° S–5° N) seems to be a dominant factor controlling how much CO2 is retained in the atmosphere via the silicate weathering feedback. The arrival of the highly weatherable Deccan Traps in the equatorial humid belt at around 50 Ma was decisive in initiating the long-term slide to lower atmospheric pCO2, which was pushed further down by the emplacement of the 30 Ma Ethiopian Traps near the equator and the southerly tectonic extrusion of SE Asia, an arc terrane that presently is estimated to account for 1/4 of CO2 consumption from all basaltic provinces that account for ~1/3 of the total CO2 consumption by continental silicate weathering (Dessert et al., 2003). A negative climate-feedback mechanism that (usually) inhibits the complete collapse of atmospheric pCO2 is the accelerating formation of thick cation-deficient soils that retard chemical weathering of the underlying bedrock. Nevertheless, equatorial climate seems to be relatively insensitive to pCO2 greenhouse forcing and thus with availability of some rejuvenating relief as in arc terranes or thick basaltic provinces, silicate weathering in this venue is not subject to a strong negative feedback, providing an avenue for ice ages. The safety valve that prevents excessive atmospheric pCO2 levels is the triggering of silicate weathering of continental areas and basaltic provinces in the temperate humid belt. Excess organic carbon burial seems to have played a negligible role in atmospheric pCO2 over the Late Cretaceous and Cenozoic.

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Section: Temperate-latitude Safety Valvesmentioning

confidence: 99%

Modulation of Late Cretaceous and Cenozoic climate by variable drawdown of atmospheric pCO2 from weathering of basaltic provinces on continents drifting through the equatorial humid belt

Kent

Muttoni

2013

Clim. Past

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“…However, the integrated effects of intrinsic changes in mineral properties and abundances, as well as extrinsic long-term changes in climate and vegetation, soil permeability and topography, commonly only reach maturity over periods of tens of thousands to millions of years (Nahon, 1991;Tardy, 1993;Thomas, 1994;Tardy and Roquin, 1998). Moreover, most of these lateritic covers have developed in those regions where prevailing transportlimited conditions have been favourable to deep and prolonged chemical weathering (Nash and McLaren, 2007;Retallack, 2010;Tardy and Roquin, 1998;Widdowson, 2003Widdowson, , 2007.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, in general, the balance between erosion and weathering rates has been in favour of deepening of the regolith by chemical weathering, rather than one of regional erosive stripping. In addition, successive periods of high and low ferruginisation (leading to the formation of different gener-ations of iron crust) have resulted from climate changes (Tardy and Roquin, 1998;Retallack, 2010).…”

Section: Introductionmentioning

confidence: 99%

Elemental weathering fluxes and saprolite production rate in a Central African lateritic terrain (Nsimi, South Cameroon)

Braun

Maréchal

Riotte

et al. 2012

Geochimica et Cosmochimica Acta

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International audienceThe comparison between contemporary and long-term weathering has been carried out in the Small Experimental Watershed (SEW) of Nsimi, South Cameroon in order to quantify the export fluxes of major and trace elements and the residence time of the lateritic weathering cover. We focus on the hillside system composed of a thick lateritic weathering cover topped by a soil layer. This study is built on the recent improvements of the hillside hydrological functioning and on the analyses of major and trace elements. The mass balance calculation at the weathering horizon scale performed with the parent rock as reference indicates (i) strong depletion profiles for alkalis (Na, K, Rb) and alkaline earths (Mg, Ca, Sr, Ba), (ii) moderate depletion profiles for Si, P, Cd, Cu, Zn, Ni and Co, (iii) depletion/enrichment profiles for Al, Ga, Ge, Sn, Pb, LREE, HREE, Y, U, Fe, V, Cr, Mn. It is noteworthy that (i) Mn and Ce are not significantly redistributed according to oxidative processes as it is the case for Fe, V and Cr, and (ii) Ge is fractionated compared to silica with enrichment in Fe-rich horizons. The calculations performed for the topsoil with iron crust as parent material reference reveal that the degradation of the iron crust is accompanied by the loss of most of the constituting elements, among which are those specifically accumulated as the redox sensitive elements (Fe, V, Cr) and iron oxide related elements like Th. The overall current elemental fluxes from the hillside system at the springs and the seepage zones are extremely low due to the inert lateritic mineralogy. 94% of the whole Na flux generated from the hillside corrected from atmospheric deposits (77 mol/ha/yr) represents the current weathering rates of plagioclase (oligoclase) in the system, the other remaining 6% may be attributed to the dissolution of hornblende. The silica hillside flux is 300 mol/ha/yr and can be mostly attributed to the plagioclase and kaolinite dissolution. Al and Ga are exported from the lateritic regolith and maybe due to the dissolution of kaolinite crystals. Compared to the other immobile elements (Zr, Hf, Nb and Th), Ti is significantly exported. Among redox-sensitive elements (Fe, V, Cr, Mn, Ce), only Ce and Mn are exported out of the hillside system. The other elements (Fe, V, Cr) are likely able to be mobilized but over a short distance only. Rb , Sr, Ba, Ni, Cu, Zn are affected by export processes. LREE and Y are exported but in very low amounts (in the range from µmol/ha/yr to mmol/ha/yr) while HREE and U are exported in negligible quantities. A first attempt is carried out to compare the mature ridge top profile from Nsimi SEW with the immature ridge top weathering profile from the Mule Hole SEW (South India), developed on similar granodioritic basement, in order to get deeper insight into (i) the contemporary saprolite production rates and (ii) the combined effect of precipitation (in terms of Mean Annual Rainfall, MAR) and evapotranspiration on the aggressiveness of the draining solutions. Consider...

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“…B, Lateritic bauxite deposits, which form mainly by deep weathering of material in silicate rock-dominated sequences. A and B modified from Retallack (2010). C, Sediment-hosted lead-zinc deposits, which form in passive margin environments.…”

Section: Geochemistrymentioning

confidence: 99%

Gallium

Foley¹,

Jaskula²,

Kimball³

et al. 2017

Professional Paper

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Lateritization and Bauxitization Events

Cited by 142 publications

References 98 publications

Modulation of Late Cretaceous and Cenozoic climate by variable drawdown of atmospheric <i>p</i>CO<sub>2</sub> from weathering of basaltic provinces on continents drifting through the equatorial humid belt

Modulation of Late Cretaceous and Cenozoic climate by variable drawdown of atmospheric <i>p</i>CO<sub>2</sub> from weathering of basaltic provinces on continents drifting through the equatorial humid belt

Elemental weathering fluxes and saprolite production rate in a Central African lateritic terrain (Nsimi, South Cameroon)

Gallium

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Lateritization and Bauxitization Events

Cited by 142 publications

References 98 publications

Modulation of Late Cretaceous and Cenozoic climate by variable drawdown of atmospheric &lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt; from weathering of basaltic provinces on continents drifting through the equatorial humid belt

Modulation of Late Cretaceous and Cenozoic climate by variable drawdown of atmospheric &lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt; from weathering of basaltic provinces on continents drifting through the equatorial humid belt

Elemental weathering fluxes and saprolite production rate in a Central African lateritic terrain (Nsimi, South Cameroon)

Gallium

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Modulation of Late Cretaceous and Cenozoic climate by variable drawdown of atmospheric <i>p</i>CO<sub>2</sub> from weathering of basaltic provinces on continents drifting through the equatorial humid belt

Modulation of Late Cretaceous and Cenozoic climate by variable drawdown of atmospheric <i>p</i>CO<sub>2</sub> from weathering of basaltic provinces on continents drifting through the equatorial humid belt