Clay mineral assemblages as indicators of hydrothermalism in the basal part of the CRP-3 core (Victoria Land Basin, Antarctica)

Clay Minerals ◽  
2009 ◽  
Vol 44 (3) ◽  
pp. 389-404 ◽  
Author(s):  
M. Setti ◽  
L. Marinoni ◽  
A. Lopez-Galindo
Keyword(s):  
Electron Microscopy ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Particle Morphology ◽  
Victoria Land ◽  
Mineral Assemblages ◽  
Variable Chemical ◽  
Victoria Land Basin ◽  
Glaciogenic Sediments ◽  
Glaciomarine Sediments

AbstractThe CRP-3 drilling project collected sediments from 3 to 939 mbsf (metres below sea floor) in the Victoria Land Basin in Antarctica. The upper sequence (down to ~790 m bsf) is of Cenozoic age and made up of detrital glaciogenic sediments; the characteristics of clay minerals in this part have been reported elsewhere. Here, the compositional features of clay minerals in the lower sequence such as conglomerates, Devonian sandstones and dolerites are described and genetic processes clarified. Clay minerals in the deepest part of the sequence derive from the alteration of different lithologies that mostly make up the sedimentary basin.Two clay mineral assemblages were characterized through analysis by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). From 790 to 823 mbsf, samples consist of authigenic smectite of variable chemical composition forming imbricated texture of plates or flakes. The smectites probably result from hydrothermal/diagenetic transformation of earlier minerals. The primary smectite cement underwent reorganization during shearing and cataclasis. The lowest part of the sequence (below 823 mbsf) is characterized by an assemblage of kaolinite, mixed-layer illite-smectite, Fe oxyhydroxide, sporadic smectite and poorly crystallized illite. It reflects a stronger alteration process than that recorded in the upper units of core CRP-3, related to hydrothermalism connected with the intrusion of an igneous body. Both assemblages show clear differences in particle morphology, texture and smectite composition to the clay assemblages found in the Cenozoic glaciomarine sediments in the upper sequence. The different phases of alteration appear related to the processes of rifting, exhumation and faulting that characterized this region since the Mesozoic.

Environmental magnetic record of Antarctic palaeoclimate from Eocene/Oligocene glaciomarine sediments, Victoria Land Basin

1998 ◽  
Vol 134 (3) ◽  
pp. 653-662 ◽  
Author(s):  
Leonardo Sagnotti ◽  
Fabio Florindo ◽  
Kenneth L. Verosub ◽  
Gary S. Wilson ◽  
Andrew P. Roberts
Keyword(s):  
Victoria Land ◽  
Magnetic Record ◽  
Victoria Land Basin ◽  
Glaciomarine Sediments

Jurassic clay mineral assemblages and their post-depositional alteration: upper Great Estuarine Group, Scotland

1987 ◽  
Vol 124 (3) ◽  
pp. 261-271 ◽  
Author(s):  
Julian E. Andrews
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Mixed Layer ◽  
Middle Jurassic ◽  
Water Circulation ◽  
Hot Water ◽  
Geothermal Gradients ◽  
Fine Grained ◽  
Igneous Intrusions ◽  
Mineral Assemblages

AbstractClay minerals from Middle Jurassic lagoonal mudrocks, siltstones and silty fine-grained sandstones of the upper Great Estuarine Group (Bathonian) are divided into four assemblages. Assemblage 1, the most common assemblage, is rich in mixed-layer illite–smectite with attendant illite and kaolinite. Assemblage 2 is dominated by smectitic clay. These assemblages are indicative of primary Jurassic deposition. Illite and kaolinite were probably derived from the weathering of older rocks and soils in the basin hinterland and were deposited in the lagoons as river-borne detritus. The majority of smectite and mixed-layer illite–smectite is interpreted as the argillization product of Jurassic volcanic dust, also deposited in the lagoons by rivers. Near major Tertiary igneous intrusions these depositional clay mineral assemblages have been altered. Assemblage 3 contains smectite-poor mixed-layer illite–smectite, whilst Assemblage 4 contains no smectitic clay at all. Destruction of smectite interlayers occurred at relatively shallow burial depths (< 2500 m) due to enhanced geothermal gradients and local convective hot-water circulation cells associated with the major Tertiary igneous intrusions.

Influence of parent material on clay minerals formation in Podzols of Trentino, Italy

Clay Minerals ◽  
2002 ◽  
Vol 37 (4) ◽  
pp. 699-707 ◽  
Author(s):  
A. Mirabella ◽  
M. Egli ◽  
S. Carnicelli ◽  
G. Sartori
Keyword(s):  
Organic Carbon ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Parent Material ◽  
Soil Horizons ◽  
Parent Materials ◽  
Subalpine Belt ◽  
Mineral Assemblages ◽  
Mineral Components ◽  
Interstratified Mineral

AbstractThe formation of clay minerals was investigated in Spodosols developed in the subalpine belt, with similar exposure, climate and age, but deriving from different parent materials. All the soils were classified as Haplic Podzols and showed the characteristic eluviation and illuviation features of Fe, Al and organic carbon. However, varying parent material lithology led to different clay mineral assemblages in the soil. Smectite could be found in the E horizons of soils developed from granodiorite and tonalite materials. Its formation was strongly dependent on the presence of chlorite in the parent material. If nearly no other 2:1 mineral components, such as chlorite, are present in the lower soil horizons, then a residual micaceous mineral becomes the dominant clay mineral. The latter derives from a mica-vermiculite interstratified mineral.

Mineralogical and geochemical characteristics (major, minor, trace elements and REE) of detrital and authigenic clay minerals in a Cenozoic sequence from Ross Sea, Antarctica

Clay Minerals ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 405-421 ◽  
Author(s):  
M. Setti ◽  
L. Marinoni ◽  
A. López-Galindo
Keyword(s):  
Trace Elements ◽  
Clay Minerals ◽  
Ross Sea ◽  
Clay Fraction ◽  
Geochemical Characteristics ◽  
Victoria Land ◽  
Victoria Land Basin ◽  
Degree Of Crystallization ◽  
Mixed Layers

AbstractThe mineralogy and geochemistry of the clay fraction of Victoria Land Basin (Ross Sea, Antarctica) sediments was investigated, to determine the origin of clay minerals and the features of authigenic smectite. The investigated core (CRP-3) is ~800 m long, mostly of Oligocene age. The clay fraction of the upper sequence consists of mica, chlorite and detrital smectite, while that of the central and lower part is largely made up of authigenic smectite. Authigenic smectites are ditrioctahedral, with a composition close to saponite, while detrital smectites such as Al-Fe beidellites are dioctahedral. Authigenic smectites have no illite mixed layers, show a higher degree of crystallization, higher MgO, Fe2O3, V, Cr, Co, Ni and Sc contents and lower SiO2, Al2O3, K2O, TiO2, Ba, Rb and Zr contents with respect to detrital clay minerals, and a clear depletion of LREE with respect to HREE. Authigenic smectite formed from the alteration of volcanic materials and clay minerals.

Clay mineral assemblages in British Lower Palaeozoic mudrocks

Clay Minerals ◽  
2006 ◽  
Vol 41 (1) ◽  
pp. 473-512 ◽  
Author(s):  
R. J. Merriman
Keyword(s):  
B Cell ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Hydrothermal Fluids ◽  
Low Grade ◽  
Lake District ◽  
Cell Dimensions ◽  
Mineral Assemblages ◽  
Lower Palaeozoic ◽  
Assemblage B

AbstractLower Palaeozoic rocks crop out extensively in Wales, the Lake District of northern England and the Southern Uplands of Scotland; they also form the subcrop concealed beneath the English Midlands and East Anglia. These mainly marine sedimentary rocks were deposited in basins created during plate tectonic assembly of the various terranes that amalgamated to form the British Isles, 400-600 Ma ago. Final amalgamation occurred during the late Lower Devonian Acadian Orogeny when the basins were uplifted and deformed, producing belts of cleaved, low-grade metasediments, so-called slate belts, with a predominantly Caledonian (NE-SW) trend. The clay mineralogy of mudrock lithologies - including mudstone, shale and slate - found in these belts is reviewed. Using X-ray diffraction data from the <2 μm fractions of ~4500 mudrocks samples, clay mineral assemblages are summarized and discussed in terms of diagenetic and low-grade metamorphic reactions, and the metapelitic grade indicated by the Kübler index of illite crystallinity.Two sequences of clay mineral assemblages, or regional assemblages, are recognized. Regional Assemblage A is characterized by a greater diversity of clay minerals in assemblages from all metapelitic grades. It includes K-rich, intermediate Na/K and Na-rich white micas, chlorite and minor amounts of pyrophyllite. Corrensite, rectorite and pyrophyllite are found in the clay assemblages of contact or hydrothermally altered mudstones. K-white micas are aluminous and phengite-poor, with b cell dimensions in the range 8.98-9.02 Å. Regional Assemblage B has fewer clay minerals in assemblages from a range of metapelitic grades. Phengite-rich K-mica is characteristic whereas Na- micas are rare, and absent in most assemblages; chlorite is present and minor corrensite occurs in mudrocks with mafic-rich detritus. Minor amounts of kaolinite are sporadically present, but dickite and nacrite are rare; pyrophyllite and rectorite are generally absent. The b cell dimensions of K-white mica in Regional Assemblage B are in the range 9.02-9.06 Å. The two regional assemblages are found in contrasting geotectonic settings. Regional Assemblage A is characteristic of the extensional basin settings of Wales, the northern Lake District and the Isle of Man. These basins have a history of early burial metamorphism associated with extension, and syn-burial or post-burial intrusive and extrusive volcanic activity. Intermediate Na/K mica probably developed from hydrothermal fluids generated around submarine volcanic centres. Deep diagenetic and low anchizonal clay mineral in these basins may develop a bedding-parallel microfabric. Chlorite-mica stacks also occur in the extensional basins and the stacking planes represent another type of bedding-parallel microfabric. Both types of microfabric are non-tectonic and developed by burial during the extensional phase of basin evolution. Regional Assemblage B is developed in the plate-convergent settings of the Southern Uplands and the southern Lake District. In the accretionary complex of the Southern Uplands the processes of burial diagenesis, metamorphism and tectonism were synchronous events. In both plate- convergent basins, low temperatures and tectonic fabric-formation had an important role in clay mineral reactions, whereas hydrothermal fluids played no part in clay genesis.

Clay mineralogy of the Permo-Triassic strata of the British Isles: onshore and offshore

Clay Minerals ◽  
2006 ◽  
Vol 41 (1) ◽  
pp. 309-354 ◽  
Author(s):  
C. V. Jeans
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
North Sea ◽  
Mixed Layer ◽  
Early Stage ◽  
Regional Distribution ◽  
Clay Mineralogy ◽  
British Isles ◽  
Mineral Assemblages ◽  
Red Bed

AbstractThe regional distribution, mineralogy, petrology and chemistry of the detrital and authigenic clay minerals associated with the Permo-Triassic strata (excluding the Rotliegend: see Ziegler, 2006; this volume), of the onshore and offshore regions of the British Isles are reviewed within their stratigraphical framework. The origin of these clay minerals is discussed in relation to current hypotheses on the developments of the Mg-rich clay mineral assemblages associated with the evaporitic red-bed Germanic facies of Europe and North Africa.Composite clay mineral successions are described for seven regions of the British Isles — the Western Approaches Trough; SW England; South Midlands; Central Midlands; the Cheshire Basin; NE Yorkshire; and the Central North Sea. The detrital clay mineral assemblages of the Early Permian strata are variable, consisting of mica, smectite, smectite-mica, kaolin and chlorite, whereas those of the Late Permian and the Trias are dominated by mica, usually in association with minor Fe-rich chlorite. The detrital mica consists of a mixture of penecontemporaneous ferric mica, probably of pedogenic origin, and recycled Pre-Permian mica. In the youngest Triassic strata (Rhaetian), the detrital clay assemblages may contain appreciable amounts of poorly defined collapsible minerals (irregular mixed-layer smectite-mica-vermiculite) and kaolin, giving them a Jurassic aspect. There are two types of authigenic clay mineral assemblages. Kaolin may occur as a late-stage diagenetic mineral where the original Permo-Triassic porewaters of the sediment have been replaced by meteoritic waters. A suite of early-stage diagenetic clay minerals, many of them Mg-rich, are linked to the evaporitic red-bed facies — these include sepiolite, palygorskite, smectite, irregular mixed- layer smectite-mica and smectite-chlorite, corrensite, chlorite and glauconite (sensu lato). The sandstones and mudstones of the onshore regions of the British Isles display little or no difference in their detrital and authigenic clay mineral assemblages. In contrast, the sandstones of the offshore regions (North Sea) show major differences with the presence of extensive chloritic cements containing Mg-rich and Al-rich chlorite, irregular mixed-layer serpentine-chlorite, and mica.

Clay mineralogy and geochemistry of early Jurassic sedimentary rocks from the Moezian Platform, northern Bulgaria

Clay Minerals ◽  
2002 ◽  
Vol 37 (3) ◽  
pp. 413-428 ◽  
Author(s):  
E. Hrischeva ◽  
S. Gier
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Sedimentary Rocks ◽  
Depositional Environments ◽  
Early Jurassic ◽  
Source Rocks ◽  
Shallow Marine ◽  
Fine Grained ◽  
Depositional Processes ◽  
Mineral Assemblages

AbstractClay minerals in early Jurassic sequences of shales, siltstones and sandstones deposited in non-marine, transitional and shallow marine environments have been examined by X-ray diffraction, electron microscopy and chemical analysis to study the relationship between clay minerals, their environment of deposition and subsequent diagenetic modifications.The inherited clay mineral composition of the fine-grained sediments reflects the influence of climate, relief, source rocks and depositional processes. Inhomogeneous clay mineral assemblages, comprising abundant kaolinite and varying proportions of illite, I-S, chlorite and vermiculite, characterize fine-grained sediments from the non-marine and transitional environments. In shallow marine depositional environments clay mineral assemblages are more uniform, dominated by illite+I-S with minor kaolinite and chlorite.The principal diagenetic process affecting fine-grained sedimentary rocks is the smectite–illite transformation. In sandstones, the authigenic formation of kaolinite, chlorite and illite appears to have been primarily determined by the environment of deposition.

A record of the Jurassic/Cretaceous boundary climatic variation on the southern margin of the Tethys : clay minerals and palynofacies of the early Cretaceous Jebel Meloussi section (Central Tunisia, Sidi Kralif Formation)

2005 ◽  
Vol 176 (2) ◽  
pp. 171-182 ◽  
Author(s):  
Johann Schnyder ◽  
Georges Gorin ◽  
Mohamed Soussi ◽  
François Baudin ◽  
Jean-François Deconinck
Keyword(s):  
Climatic Change ◽  
Sea Level ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Climatic Variation ◽  
Northern Margin ◽  
Sequence Stratigraphic ◽  
Central Tunisia ◽  
Mineral Assemblages

Abstract In order to precise the paleogeographic extension of the climatic variation known at the Jurassic/Cretaceous boundary, the sedimentary organic matter (palynofacies and Rock-Eval) and the clay minerals content of Berriasian sediments of the Sidi Kralif Formation are studied on the Jebel Meloussi section, central Tunisia. Standard sedimentological and palynofacies analysis allow to reconstruct the bathymetric curve and the sequence stratigraphic scheme. Using existing biostratigraphy based on calpionellids and ammonite zonation, the sequence stratigraphic interpretation can be correlated with the established eustatic chart. Clay mineral assemblages are characterized by a shift in the kaolinite content, recorded at the end of the calpionellid zone B, at the early/middle Berriasian boundary, at a time of high long-term sea-level (MFS Be2, second order eustatic peak). A contemporary change in the clay mineral assemblages, interpreted as a climatic change, is known from the boreal area, and from the northern margin of the Tethys Sea. That change is also documented southerly in southern Morocco (Agadir area), on the Atlantic domain. A late Tithonian to early Berriasian dry and cooler phase is replaced by a middle to late Berriasian more humid phase, indicated by a general increase in kaolinite in the clay mineral assemblages. The trend from a dry climatic phase to a more humid one, recorded on the boreal domain and along the northern margin of the Tethys is also recorded in lower paleolatitudes of Tunisia, on the southern margin of the Tethys, in better dated outcrops than the ones of Morocco. The results obtained in Tunisia show that the beginning of the climatic change was precisely synchronous on both margins, and occurred within the same long-term high sea-level context.

The origin of the Triassic clay assemblages of Europe with special reference to the Keuper Marl and Rhaetic of parts of England

1978 ◽  
Vol 289 (1365) ◽  
pp. 549-636 ◽  
Keyword(s):  
Special Reference ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Mixed Layer ◽  
North Africa ◽  
Western Europe ◽  
Water Masses ◽  
Mineral Assemblages

Hypotheses are reviewed on the origin of the magnesium-rich Triassic clays which characterize the Germanic facies of western Europe and north Africa. Relations between clay minerals, megafacies and stratigraphy are described from 28 localities in the Triassic Keuper Marl, Tea Green Marl and Rhaetic sediments of England. Two clay mineral assemblages are recognized: (1) a detrital assemblage of mica with minor chlorite which occurs throughout all the sediments investigated, and (2) a neoformed assemblage of magnesium-rich clay minerals with a limited occurrence related to certain megafacies cycles which resulted from the transgression and regression of the Alpine facies into the Germanic facies; this assemblage includes sepiolite, palygorskite, chlorite, smectite, corrensite and irregular mixed-layer smectite/mica and smectite/chlorite minerals. The clay mineral neoformations resulted from reactions between the water masses in which the Germanic and Alpine facies were deposited. Controlling the distribution and types of minerals neoformed were the general and local variations in the chemistries of the Alpine and Germanic water masses, as well as competition for available magnesium from other mineral-forming reactions.

Clay mineral studies of the Tripoli Formation (Lower Messinian), Sicily

Clay Minerals ◽  
1988 ◽  
Vol 23 (3) ◽  
pp. 309-321 ◽  
Author(s):  
E. Azzaro ◽  
A. Bellanca ◽  
R. Neri
Keyword(s):  
Chemical Composition ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Early Diagenesis ◽  
Isotopic Data ◽  
Mineral Assemblages ◽  
Wide Variability ◽  
Dioctahedral Smectite ◽  
Primary Composition

AbstractThe characterization of clay mineral assemblages in the diatomite-dominated Tripoli Formation (Lower Messinian, central Sicily) has resulted in delineation of suites dominated by generally well-crystallized dioctahedral smectite and illite of low crystallinity, with lesser amounts of kaolinite and chlorite. These minerals are thought to have a mainly detrital origin related to the calcareous and marly formations exposed in the margins of the depositional area. Vertical fluctuations of the montmorillonite/illite ratio and changes of the crystallinity and chemical composition of these phyllosilicates support environmental interpretations from isotopic data of associated carbonates, and point to a wide variability of depositional conditions ranging from evaporating to brackish. Early diagenesis of the clay minerals was controlled by the primary composition of the sediment which, in turn, affected the porewater chemistry.

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