Clay Sedimentology

Chamley, Hervé

doi:10.1007/978-3-642-85916-8

Cited by 861 publications

(551 citation statements)

References 487 publications

(760 reference statements)

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“…A large portion of this clay consists of Fe-smectites, and it is conceivable that with diagenesis at higher temperatures, the Fe-smectites may be transformed, releasing Fe and Silica. The processes and conditions for smectite decomposition or transformation to illite or chlorite are poorly understood (Chamley, 1989, andWeaver, 1989, and references therein). Perhaps with either longer or deeper burial, these clay-rich radiolarites will undergo further silicification and segregation of clay.…”

Section: Deep-ocean Pacific Radiolaritesmentioning

confidence: 99%

Jurassic through Early Cretaceous Sedimentation History of the Central Equatorial Pacific and of Sites 800 and 801

Ogg¹,

Stattegger²,

Behl³

1992

Proceedings of the Ocean Drilling Program

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Sedimentation in the central Pacific during the Jurassic and Early Cretaceous was dominated by abundant biogenic silica. A synthesis of the stratigraphy, lithology, petrology, and geochemistry of the radiolarites in Sites 801 and 800 documents the sedimentation processes and trends in the equatorial central Pacific from the Middle Jurassic through the Early Cretaceous. Paleolatitude and paleodepth reconstructions enable comparisons with previous DSDP sites and identification of the general patterns of sedimentation over a wide region of the Pacific.Clayey radiolarites dominated sedimentation on Pacific oceanic crust within tropical paleolatitudes from at least the latest Bathonian through Tithonian. Radiolarian productivity rose to a peak within 5° of the paleoequator, where accumulation rates of biogenic silica exceeded 1000 g/cm 2 /m.y. Wavy-bedded radiolarian cherts developed in the upper Tithonian at Site 801 coinciding with the proximity of this site to the paleoequator. Ribbon-bedding of some radiolarian cherts exposed on Pacific margins may have formed from silicification of radiolarite deposited near the equatorial high-productivity zone where radiolarian/clay ratios were high. Silicification processes in sediments extensively mixed by bioturbation or enriched in clay or carbonate generally resulted in discontinuous bands or nodules of porcellanite or chert, e.g., a "knobby" radiolarite. Ribbon-bedded cherts require primary alternations of radiolarian-rich and clay-rich layers as an initial structural template, coupled with abundant biogenic silica in both layers. During diagenesis, migration of silica from clay-rich layers leaves radiolarian "ghosts" or voids, and the precipitation in adjacent radiolarite layers results in silicification of the inter-radiolarian matrix and infilling of radiolarian tests. Alternations of claystone and clay-rich radiolarian grainstone were deposited during the Callovian at Site 801 and during the Berriasian-Valanginian at Site 800, but did not silicify to form bedded chert.Carbonate was not preserved on the Pacific oceanic floor or spreading ridges during the Jurassic, perhaps due to an elevated level of dissolved carbon dioxide. During the Berriasian through Hauterivian, the carbonate compensation depth (CCD) descended to approximately 3500 m, permitting the accumulation of siliceous limestones at near-ridge sites. Carbonate accumulation rates exceeded 1500 g/cm 2 /m.y. at sites above the CCD, yet there is no evidence of an equatorial carbonate bulge during the Early Cretaceous. In the Barremian and Aptian, the CCD rose, coincident with the onset of mid-plate volcanic activity.Abundance of Fe and Mn and the associated formation of authigenic Fe-smectite clays was a function of proximity to the spreading ridges, with secondary enrichments occurring during episodes of spreading-center reorganizations. Callovian radiolarite at Site 801 is anomalously depleted in Mn, which resulted either from inhibited precipitation of Mn-oxides by lower pH of interstitial waters in...

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Section: Deep-ocean Pacific Radiolaritesmentioning

confidence: 99%

Jurassic through Early Cretaceous Sedimentation History of the Central Equatorial Pacific and of Sites 800 and 801

Ogg¹,

Stattegger²,

Behl³

1992

Proceedings of the Ocean Drilling Program

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“…In fact, a typ i cal pedogenic evo lu tion con sists of the al ter ation of illite with the for ma tion of ver mic u lite, smectitic mixed lay ers, smectite, kaolinite and amor phous com pounds (Millot, 1970;Jack son, 1964;Chamley, 1989). How ever, kaolinite is re ported as a pri mary con stit u ent of the lime stone bed rock crop ping out in the Montagnola Senese (Gandin et al, 2000;Iacoviello and Mar tini, 2012) and for this rea son its oc cur rence in the cave-sed i ments does not pro vide any in for ma tion about the degree pedogenetic weath er ing.…”

Section: Discussionmentioning

confidence: 99%

Clay minerals in cave sediments and terra rossa soils in the Montagnola Senese karst massif (Italy)

Iacoviello

Martini

2013

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“…In the catchment of Lake Baikal, illite is a dominant parental mineral located in Proterozoic and Archean granites (Galazy et al, 1993;USGS Central Energy Data Management, 2001). Illite weathering starts with an opening of the clay sheets and loss of interfoliar K + by leaching (i.e., degradation process ;Chamley 1989;Thorez, 1989).…”

Section: Weathering Conditions In the Catchment Of Lake Baikalmentioning

confidence: 99%

“…Clay minerals have been widely used as proxies for climate reconstruction in marine and lacustrine environments (e.g., Chamley, 1989). Clays are either primary minerals inherited from parental rocks by physical erosion or secondary minerals produced by chemical weathering.…”

Section: Introduction -Clays As Palaeoclimate Proxy: the Case Study Omentioning

confidence: 99%

Clay-mineral record in Lake Baikal sediments: The Holocene and Late Glacial transition

Fagel

Boës

2008

Palaeogeography, Palaeoclimatology, Palaeoecology

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Abstract:We analyse the clay-mineralogical composition of two 1-m long cores from elevated plateaus in the southern and northern basins of Lake Baikal. Our aim is to test the limits of classically used clay proxies for climate reconstructions. Mineralogical signature is determined by X-ray diffraction on oriented aggregates from Holocene and Late Glacial sediments. Mineralogical results are presented on a palaeomagnetic-derived time scale. Sampling at a centimeter resolution allows for a sub-millenial order reconstruction. The evolution of clayderived climate proxies (smectite/illite peak intensity ratio, S/I) is compared between the two locations, with respect to other climate reconstructions for the Lake Baikal area and Siberia. During the Late Glacial punctual increases of S/I are related to changes of particle source rather than any climate change. At both sites the most intense chemical weathering conditions occured during the Subboreal, lagging the Eurasian middle Atlantic climate optimum. S/I follows a gradual but irregular increase through the Holocene, probably related to slow warming favourable to the development of the Siberian soils. The different sensitivity to hydrolysing conditions in northern and southern sites can be explained by a combination of local lithological and topographical parameters.

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Clay Sedimentology

Cited by 861 publications

References 487 publications

Jurassic through Early Cretaceous Sedimentation History of the Central Equatorial Pacific and of Sites 800 and 801

Jurassic through Early Cretaceous Sedimentation History of the Central Equatorial Pacific and of Sites 800 and 801

Clay minerals in cave sediments and terra rossa soils in the Montagnola Senese karst massif (Italy)

Clay-mineral record in Lake Baikal sediments: The Holocene and Late Glacial transition

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