Heavy Mineral Associations Research Articles

Heavy and Light Mineral Association of Late Quaternary Permafrost Deposits in Northeastern Siberia

We studied heavy and light mineral associations from two grain-size fractions (63–125 μm, 125–250 µm) from 18 permafrost sites in the northern Siberian Arctic in order to differentiate local versus regional source areas of permafrost aggradation on the late Quaternary time scale. The stratigraphic context of the studied profiles spans about 200 ka covering the Marine Isotope Stage (MIS) 7 to MIS 1. Heavy and light mineral grains are mostly angular, subangular or slightly rounded in the studied permafrost sediments. Only grains from sediments with significantly longer transport distances show higher degrees of rounding. Differences in the varying heavy and light mineral associations represent varying sediment sources, frost weathering processes, transport mechanisms, and post-sedimentary soil formation processes of the deposits of distinct cryostratigraphic units. We summarized the results of 1141 microscopic mineral analyses of 486 samples in mean values for the respective cryostratigraphic units. We compared the mineral associations of all 18 sites along the Laptev Sea coast, in the Lena Delta, and on the New Siberian Archipelago to each other and used analysis of variance and cluster analysis to characterize the differences and similarities among mineral associations. The mineral associations of distinct cryostratigraphic units within several studied profiles differ significantly, while others do not. Significant differences between sites as well as between single cryostratigraphic units at an individual site exist in mineral associations, heavy mineral contents, and mineral coefficients. Thus, each study site shows individual, location-specific mineral association. The mineral records originate from multiple locations covering a large spatial range and show that ratios of heavy and light mineral loads remained rather stable over time, including glacial and interglacial periods. This suggests mostly local sediment sources and highlights the importance of sediment reworking under periglacial regimes through time, including for example the formation of MIS 1 thermokarst and thermo-erosional deposits based on remobilized MIS 3 and 2 Yedoma Ice Complex deposits. Based on the diverse mineralogical results our study supports the viewpoint that Yedoma Ice Complex deposits are mainly results of local and polygenetic formations (including local aeolian relocation) superimposed by cryogenic weathering and varying climate conditions rather than exclusive long distance aeolian transport of loess, which would have highly homogenized the deposits across large regions.

Paleogeographic implications of a multi-parameter Paleogene provenance dataset (Transylvanian Basin, Romania)

ABSTRACTRecent developments in geoanalytics have led to the rapidly increasing potential of sedimentary provenance analysis in paleogeographic reconstructions. Here we combine standard methods (petrography, zircon U-Pb geochronology, optical heavy-mineral identification) with modern techniques such as automated Raman-spectroscopic identification of heavy minerals and detrital apatite and titanite U-Pb geochronology. The resulting multi-parameter dataset enables the reconstruction of tectonic and paleogeographic environments to an as-yet unprecedented accuracy in space and time. The Paleogene siliciclastic formations of our study area, the Transylvanian Basin, represent an intensely changing sedimentary environment comprising three transgressive–regressive cycles on a simultaneously moving and rotating tectonic plate. We identified six major source components of the Paleogene sediments and outlined the paleo-drainage patterns for the three cycles, respectively. According to our data these components include: 1) pre-Variscan basement units of the nappes, 2) Variscan granitoids, 3) Permo-Triassic felsic volcanic rocks, 4) Jurassic ophiolites, 5) Upper Cretaceous granodiorites, and 6) Priabonian to Rupelian (37–30 Ma) intermediate magmatites, the latter representing newly recognized formations in the region. Abrupt paleographic changes can be directly deduced from the obtained dataset. The first phase of the Paleogene siliciclastic sequence is composed of mostly Southern Carpathian–derived sediments, to which Jurassic ophiolite detritus of the Apuseni Mts. was added during the second phase, while the siliciclastic material of the third phase represents mainly recycled material from the second phase. According to the detected diagnostic heavy-mineral associations, U-Pb age components and the positions of the potential source areas a set of provenance maps are presented.

Строение, состав и условия формирования четвертичных отложений в Кельтминском погребенном каньоне (юго-восток Республики Коми)

Our lithological study of the Quaternary strata in the section of the well 17843 resulted in identification of three sediments sequences of various thickness and composition. In the lower part of the well, at depths of 43.2—27 m (layers 5, 4d and 4c), the sediments were formed probably in fluvioglacial conditions. The sediments are characterized by high content of ilmenite — 7—14 %, and group of titanium minerals — 7—12 %, where concentrations of leucoxene and titanite are increased. The content of chromespinellides increases downwards from 2 to 4.4 %. In the depth interval 25.9—23.6 m (lay 4b), a dense, poorly-sorted silty clay without clastic material is exposed; its genesis is unclear. Clay is characterized by the highest amount of heavy fraction in the section — 1.91 %, and contains an abnormally high amount of magnetite — on average 31 %. The upper 22 m of the sequence (layers 4a and 3—1) are represented by alluvium — well-sorted medium-fine-grained sand with amphibole-ilmenite-garnet-epidote association of heavy minerals and increased amounts of metamorphic minerals — 7—10 %, chromespinellides — 4—6 %, and magnetite — 4—8 %. Such complex of heavy minerals in the sediments, forming the canyon, testifies to the participation of the Ural magmatic and metamorphic complexes in their formation; the supply of minerals from the Kama seems to be very problematic. Palynological analysis data obtained from layers 5, 4d, and 4b reflect a regular vegetation change of the final stages during the interglacial. Spruce-pine forests with fir, cedar, treelike and dwarf birches, alder and willow were gradually replaced by tundra plant communities, where, along with bog-tundra formations, there were xerophytic communities with wormwood Artemisia sp., Chenopodiaceae, and rare Ephedra sp.

Záznam post-paleozoického geologického vývoje uchovaný v reliktech miocénu v Brně – Líšni

Recent operation in the Kalcit Quarry near Brno-Líšeň exposed contact of Devonian limestones with overlying Miocene sediments. Calcareous silts with chert debris and non-calcareous clays fi lling the cleft s in the limestone are Middle Miocene in age (Lower Badenian). They contained association of translucent heavy minerals derived from Drahany Culmian formations and the Brno Massif. Fossil content comprised conodonts and foraminifers weathered off the Lower Carboniferous limestones, brackish gastropods reworked from the Rzehakia Beds (Ottnangian) and foraminifers reworked from Karpatian and Lower Badenian clays. Overlying grey gravelly sand contained varied association of heavy minerals reworked from post-Jurassic products of tropical weathering and block of Paleogene silcrete. Finally, the Lower Badenian Brno Sands capping the section contained rich pseudoassociation of foraminifers reworked from the Karpatian and Badenian sediments nearby as well as Upper Cretaceous and Paleogene foraminifers from more distant edge of the Carpathian Flysch Belt.

Neogenní a kvartérní sedimenty v oblasti Nového Hrádku (západní část NP Podyjí)

Neogene deposits of the Carpathian Foredeep were newly recognized in the sedimentary succession within the outcrop close to Nový Hradek site in the area of the Podyjí National Park covered by extensive Quaternary deposits. These deposits are preserved as erosional relics within a bowl shaped depression on the top of the crystalline basement. Facies analysis shows that the recognised Neogene beds represent fluvial deposits. Two facies associations were identified within the Quaternary deposits. Although both of them are interpreted as colluvial deposits, they were formed by a series of gravity flows with highly varied water content. The provenance analysis (pebble petrography, association of heavy minerals, zircon study) confirmed, that the source area of both Neogene and Quaternary deposits was located in the adjacent geological units with strong dominance of Moravian Unit. Relatively high mineral maturity of the studied deposits points to extended blanket of intensely weathered crystalline basement, which underwent erosion and redeposition. Higher content of quartz clasts within the Neogene deposits reveals different mode of transport and possible redeposition from older sediments. Studied Neogene deposits are preliminary related to quartzose gravel and sands known from the close surrounding of the nearby Lukov village. Comparison of Neogene and Quaternary deposits in the surroundings of Nový Hrádek and occurrences of similar sediments within the National Park in Austria (e.g. surroundings of Merkersdorf) might provide a further data about the poorly known history of the area during Neogene.

The Existence of Tin Placer Relation With Tin Belt In Kundur Waters Area Riau archipelago Province

Placer mineral is mineral deposits that have channels transportation as particles of grains mineral in the river and on the ocean floor. The most common and plentiful placer mineral are rutile, tin, magnetite, ilmenite, zircon and many gems. The existence of ancient rivers flooded after the end of the ice age, of the ancient river many deposited heavy minerals from rocks around the island of Sumatra and Kalimantan. The existence of an ancient channel formed at the Holocene is thought to be a valley that has the potential as mineral deposits to be transported and deposited in the same time with the sediments that fill the valleys. Tin Gravel is one of the heavy minerals in Sunda shelf deposited above the ancient valleys of granite rock The type of granite in Sunda shelf is granite I type (east belt) and S type (middle belt). The granite belt (tin belt) is related to the heavy mineral associations found in the study area, whether derived from granite I type or granite S Type is still a subject of debate among researchers. The granite type classification is based on opaque minerals. The magnetite series comprises of: magnetite, ilmenite, hematite and pyrite, while the ilmenite series consists of: cassiterite, ilmenite, and graphite. Granite in Indonesia islands containing tin mineral included in the middle belt (type S), and east belt (type I). Occurred on a Carbon, Perm and also Triass age. Granites are distributed almost along the coastal to offshore of Kundur Island. Tin (SnO2), or tin include oxide group, brownish, prismatic. Tin deposited is associated with acid igneous rock formed on pegmatites accumulation. In Study area tin founded in 16 samples of seabed surface sediments with the largest content of 0.04124% and the smallest 44 of 0.0006%. The purpose of this study is to know the existence of placer tin content in marine sediments in Kundur waters, its relation with tin belt (granite type), whereas the purpose of the study is to know the source of tin placer.

Sand beaches on highly indented karstic coasts: Where the sands come from and what should be protected (SE Adriatic, Croatia)

This study deals with sand beaches of the SE Adriatic archipelago and Pelješac Peninsula. The beaches themselves, as well as their genetically related surroundings are taken into consideration, as both are critical for understanding beach features and processes. Two approaches have been followed in these two areas: the study of sediment composition including heavy mineral associations and the study of geology, morphology and sediment distribution. These features and their combination present the basis for interpretation of present-day processes, as well as for reconstructing how and where the beaches developed and why have they in some places disappeared.Sediment composition of the studied beaches clearly indicates Pleistocene deposits as the principal sediment source. However, much of this supplied sediment has a short residence time on the beaches due to marine reworking and the bulk of the beach sediment arrives from the sea floor.The positioning of the studied sand beaches at bayheads, their lengths and shapes, as well as their present status, have been influenced by several main factors. They include: (1) pre-Pleistocene tectonic deformations, (2) pre-Pleistocene weathering and erosion of carbonate sediments, mainly Cretaceous in age, (3) initial distribution of “soft” Pleistocene cover sediments, as well as (4) the history of their reduction and related decline in sediment source capacity or at some locations their complete disappearance. Other main factors are (5) the post-LGM sea-level rise and (6) two climatic events: an important pluvial period from 8.4 to 6 ka BP (maximum from 7 to 6 ka BP) and the transition to Mediterranean climate between 6 and 5.5 ka BP. Beaches with relatively high Pleistocene hinterland supply and correlative, relatively large widths seem to be quasi-stable or possibly even prograde. Beaches of small width and minor to negligible hinterland supply, or those completely deprived of it, suggest ongoing beach recession.Suggested priorities for the protection of the beaches are directly related to the preservation of hinterland supply. In the case of beaches with negligible or no hinterland sediment supply replenishment projects can be considered.

Heavy Minerals for Junior Woodchucks

In the last two centuries, since the dawn of modern geology, heavy minerals have been used to investigate sediment provenance and for many other scientific or practical applications. Not always, however, with the correct approach. Difficulties are diverse, not just technical and related to the identification of tiny grains, but also procedural and conceptual. Even the definition of “heavy minerals” is elusive, and possibly impossible. Sampling is critical. In many environments (e.g., beaches), both absolute and relative heavy mineral abundances invariably increase or decrease locally to different degrees owing to hydraulic-sorting processes, so that samples close to "neutral composition" are hard to obtain. Several widely shared opinions are misleading. Choosing a narrow size-window for analysis leads to increased bias, not to increased accuracy or precision. Only point-counting provides real volume percentages, whereas grain-counting distorts results in favor of smaller minerals. This paper also briefly reviews the heavy mineral associations typically found in diverse plate-tectonic settings. A mineralogical assemblage, however, only reproduces the mineralogy of source rocks, which does not correlate univocally with the geodynamic setting in which those source rocks were formed and assembled. Moreover, it is affected by environmental bias, and by diagenetic bias on top in the case of ancient sandstones. One fruitful way to extract information on both provenance and sedimentological processes is to look for anomalies in mineralogical–textural relationships (e.g., denser minerals bigger than lower-density minerals; harder minerals better rounded than softer minerals; less durable minerals increasing with stratal age and stratigraphic depth). To minimize mistakes, it is necessary to invariably combine heavy mineral investigations with the petrographic analysis of bulk sand. Analysis of thin sections allows us to see also those source rocks that do not shed significant amounts of heavy minerals, such as limestone or granite, and helps us to assess heavy mineral concentration, the “outer” message carrying the key to decipher the “inner message” contained in the heavy mineral suite. The task becomes thorny indeed when dealing with samples with strong diagenetic overprint, which is, unfortunately, the case of most ancient sandstones. Diagenesis is the Moloch that devours all grains that are not chemically resistant, leaving a meager residue difficult or even impossible to interpret when diagenetic effects accumulate through multiple sedimentary cycles. We have conceived this friendly little handbook to help the student facing these problems, hoping that it may serve the purpose.

Geological and paleooceanological significance of psephite from the cretaceous-cenozoic deposits from the near-pole part of the Lomonosove ridge

The article gives a characteristic of the psephitic material obtained in the IODP-302 well on the Lomonosov Ridge. We provide data on the shape of rock fragments, their roundness, petrographic composition and distribution over lithological units of the well. It is shown that the major part of the psephites was delivered to the drilling point with ice, but several samples have a local origin and characterize the composition of the Mesozoic rocks. The roundness of the psephites consistently deteriorates in the younger enclosing sediments. The paper presents arguments that link this trend with the intensification of the ice regime. The consequence of the ice cover increase is the shortening of the time of psephites occurrence in the wave-surf zone, where large-sized material is rounding, by activating the “anchor” mechanism of the rock fragments capture. The level of change in petrographic associations of psephites generally coincides with the level of change in the association of heavy minerals, which is a consequence of the appearance of more distant sources areas. It is shown that the “paleo–trans–polar” ice drift system began to function in the middle Miocene. The paper draws conclusions about the evolution of the ice regime in the Arctic Ocean during the Cenozoic.

Geochemistry of heavy minerals and U–Pb detrital zircon geochronology in the Manantiales Basin: Implications for Frontal Cordillera uplift and foreland basin connectivity in the Andes of central Argentina

The Manantiales Foreland Basin, located at ~32°15′S in the Frontal Cordillera, Argentina, contains the sedimentary record of erosion of igneous basement and Miocene volcanic rocks exhumed during the Andean orogeny. U–Pb ages of detrital zircons from the basin fill succession (Chinches Formation) constrain the onset of deposition to ca. 22Ma (early Miocene). We present the first geochronological control (ca. 22Ma) from the lower part of the Manantiales Foreland Basin (Areniscas Chocolate member) on the basis of U–Pb ages of detrital zircons, shedding light about an older initiation of this foreland basin. The main heavy mineral association in the sedimentary basin, clinopyroxene+amphibole, indicates two events of volcanic supply, probably corresponding to the Farellones Formation in the Principal Cordillera, and the La Ramada Volcanic Complex and subvolcanic rocks similar to the La Laguna body in the Argentinean Frontal Cordillera. Detrital zircon geochronology indicates dominant sourcing from upper Paleozoic–lower Triassic Choiyoi Magmatic Province rocks. Initial sediment supply at ca. 22–19Ma was from the Cenozoic volcanic arc of the Principal Cordillera. At ca. 19Ma, exhumation of the Frontal Cordillera was registered by supply from the Choiyoi Magmatic Province, related to tectonic uplift of a western block (La Ramada–El Espinacito ranges) through a thrust of the La Ramada fold-and-thrust belt. At ca. 16Ma, supply from the Cenozoic volcanic arc recommenced, providing evidence for capture and erosion of the Principal Cordillera, which could be related to thrusting in normal sequence of the La Ramada fold-and-thrust belt. At ca. 10Ma, the La Ramada Volcanic Complex and rocks similar to the La Laguna subvolcanic body became a local source of sediment for the basin. The Manantiales Foreland Basin was linked to Neogene sedimentary basins in the Precordillera at its first part in its history, between ca. 22 and 19Ma and probably until ca. 12Ma, when the eastern Frontal Cordillera (Cordillera del Tigre) and Precordillera were uplifted, and the foreland basin was broken. Thus, the Frontal Cordillera was uplifted through two diachronous thick-skinned blocks from west (La Ramada–El Espinacito ranges) to east (Cordillera del Tigre). This result can explain the diverse ages for uplift deduced for the Frontal Cordillera in previous studies, where it has been considered rather as a singular N-S block. The source of late Mesoproterozoic detrital zircons registered in the Manantiales Basin is uncertain, but we infer recycling from Mesozoic sedimentary rocks of the Principal Cordillera.

Tsunami deposits of September 21st 1985 in Barra de Potosí: comparison with other studies and evaluation of some geological proxies for southwestern Mexico

Residents of Barra de Potosí village in southwestern Mexico witnessed inundation by waves up to a distance of ~500 m from the shore after the Mw 7.5 earthquake on September 21st, 1985. Sediments deposited by the tsunami wave were identified near El Potosí estuary and their geological characteristics (sedimentology, mineralogy and chemical composition) were compared with pre-tsunami sediments and deposits from the nearby-unaffected area. Tsunami sediments were characterized by well and moderately well sorted (standard deviation: 0.4-0.7 Φ) fine sand (mean size: 2.13-2.47 Φ) and contain higher amounts of both finer and coarser fractions (negative to positive skewed) and had leptokurtic to extremely leptokurtic distribution. Sedimentological characteristics of tsunami and pre-tsunami deposits were similar. Abundance and association of heavy minerals were also comparable both in tsunami and pre-tsunami deposits. However, lower amounts of Br and Fe2O3 and higher SiO2 and TiO2 differentiate tsunami deposits from the pre-tsunami sediments. Comparison with sediments deposited during the tsunamis of March 14th, 1979, September 21st, 1985, and March 11th, 2011, in the region did not yield any characteristic signature. Except for stratigraphy (i.e., erosive base), no other geological characteristic was useful for identifying paleo-tsunami in the region.

The mineralogy of suspended matter, fresh and Cenozoic sediments in the fluvio-deltaic Rhine–Meuse–Scheldt–Ems area, the Netherlands: An overview and review

AbstractMinerals are the building blocks of clastic sediments and play an important role with respect to the physico-chemical properties of the sediment and the lithostratigraphy of sediments. This paper aims to provide an overview of the mineralogy (including solid organic matter) of sediments as well as suspended matter as found in the Netherlands (and some parts of Belgium). The work is based on a review of the scientific literature published over more than 100 years. Cenozoic sediments are addressed together with suspended matter and recent sediments of the surface water systems because they form a geoscientific continuum from material subject to transport via recently settled to aged material. Most attention is paid to heavy minerals, clay minerals, feldspars, Ca carbonates, reactive Fe minerals (oxides, siderite, sulphides, glauconite) and solid organic matter because they represent the dominant minerals and their properties form a main issue in subsurface and water management. When possible and relevant, the amounts, provenance, relationship with grain size distribution, early diagenesis and palaeohydrological evolution are described. Tables with statistical data about the mineral contents and isotopic composition of carbonates and organic matter are presented as overviews. The review on the mineralogy of Dutch fluvial and marine environments is more extensive than that for the other sedimentary environments because the first two have been studied much more intensively than the others and they also form the larger part of the Dutch deposits. The focus is on the natural background mineralogy of Dutch sediments, but this is hard for recent sediments, largely because the massive hydraulic infrastructure present in the Netherlands has probably also affected the mineralogy and geochemistry of sediments deposited in recent centuries. Many findings are summarised, several of which lead to more general insights for the Dutch situation. Ca carbonates in sediments often have several provenances and thus must be considered as mixtures. Dolomite is commonly present in addition to calcite. The importance of biotite as weatherable mica is unclear. Weathering of heavy minerals plays some role but it is unclear in which way it affects the heavy mineral associations. Clays are usually dominated by illite, smectite and their interstratified variant, while kaolinite is usually below 20% and chlorite below 5%. Vermiculite is a minor constituent in fluvial clays and its illitisation presumably happens during early diagenesis in the marine environment. Opaque Fe hydroxides can be present in addition to Fe oxyhydroxide coatings and both will play a role in redox chemistry as reactive Fe minerals. Feldspars in marine sediments must be present but they have not been properly studied. The genesis of rattle stones and carbonate concretions has not been completely elucidated. The fraction of terrigeneous organic matter in estuarine and coastal marine sediments is substantial. The available data and information are spread irregularly over the country and the reviewed information discussed in this paper is derived from relatively small-scale studies dealing with a limited amount of analysed samples. Much information is available from the Scheldt estuaries in the southwestern part of the Netherlands partly due to the severe contamination of the Western Scheldt in recent decades.

Mineral composition of tephra layers in the Quaternary deposits of the Sea of Okhotsk:: Heavy minerals associations and their geochemistry

Heavy mineral associations from tephra layers in the Quaternary deposits of the Sea of Okhotsk and their chemical characteristics were studied by various techniques. It was shown that such investigations may have a bearing on the problems of tephrostratigraphic correlation. We assessed the possibility of application of the mineral composition of distal tephra for identification and, in particular, estimation of the relation of tephras to the explosive volcanism of back-arc and frontal zones of island arcs. The investigation of the compositions of minerals and use of mineral geothermometers and geobarometers (two-pyroxene, magnetite–ilmenite, and amphibole) provided evidence on the physicochemical parameters of melt crystallization during the explosive volcanic eruptions that produced the distal tephra layers. It was established that the pyroclastic material of some tephra layers was supplied during explosive eruptions not only from shallow magma chambers but also from deeper and higher temperature reservoirs. Together with the geochemical signatures of volcanic glasses, the obtained results on mineral associations and the geochemistry of mineral inclusions are applicable for the comparative analysis and correlation of tephras from marine and continental sequences, as well as for the identification of explosive volcanic products in adjacent land areas.

COMPOSITION AND PROVENANCE OF GRÖDEN SANDSTONE FROM THE VELEBIT MTS.

Six samples of Groden sandstones (Middle Permian) were analysed: Five of them were from Pikovac Creek valley (in the vicinity of Brusane village at Velebit Mts., Croatia) and one was from the locus typicus Groden/Val Gardena (Italy). Based on the micropetrographical characteristics of sandstones, as well as on the modal composition and heavy mineral association, origin of material, weathering index of source rocks, climate and relief in the period of deposition have been supposed. Four samples from Pikovac Creek were petrographicaly determined as lithic greywackes, one as densely packed lithic arenite, while a specimen from Groden locus typicus represents feldspar greywacke. Lithic greywackes/arenites imply very low maturity and suggest a close proximity of source rocks as well as the active tectonics in the hinterland of the depositional basin. Heavy mineral association in the samples from Pikovac Creek valley, with a large amount of fairly rounded stable grains (zircon, tourmaline and rutile), indicate that clastic material was derived from recycled orogen, and probably from reworked sedimentary rocks. The presence of kyanite and chlorite in the heavy mineral assemblage suggest their origin is from metamorphic rocks. This data assumes that Groden sandstones from Pikovac Creek were possibly deposited in the fan delta or braided delta depositional environment as a part of a rift system (recycled orogen). The composition of the sample Groden s. locus typicus (light and heavy mineral fractions) suggests the vicinity of magmatic rocks in the source area. All analysed samples are red coloured and have a large amount of limonitized grains in the heavy mineral assemblage, that point to the arid climate at the time of deposition. A weathering index diagram for Pikovac sandstones implies an arid/semiarid climate and high relief of the source area where metamorphic or sedimentary rocks dominate, while an arid/semiarid climate and high relief with plutonic source rocks were supposed for the provenance of Groden s. locus typicus.

Depositional environment and provenance of the Gresten Formation (Middle Jurassic) on the southeastern slopes of the Bohemian Massif (Czech Republic, subsurface data)

The deposits of the Gresten Formation (Midle Jurassic) obtained from deep wells in the territory of southern Moravia (Czech Republic) have been newly examined with the aim to better describe their provenance and depositional environment. Deposition within a relatively broad flood plain with fluvial/distributive channels, crevasse channels, crevasses splays and coal-swaps have been recognised in the majority of well cores. Basinal/open marine deposits have been less common. The heavy mineral association is quite stable, with significant dominance of garnet and commonly also with high content of zircon. The mineralogical spectra of garnet types were broad with strong dominance of almandines. The rutiles were mostly derived from metapelites and additionally also from metamafic rocks and pegmatites. The results point to mixed sources from both intensively weathered crystalline rocks of the eastern margin of the Bohemian Massif (primary source) and the older sedimentary rocks - especially from the Moravo-Silesian Paleozoic deposits (recycled source).

The Piolit, Pelat and Baiardo Upper Cretaceous flysch formations (western Alps): geodynamic implications at the time of the Pyrenean tectonic phases

AbstractThe Piolit, Pelat (French Alps) and Baiardo (Italian Maritime Alps) units contain Upper Cretaceous carbonate turbidites formations, with minor siliciclastic components. They are flysch formations, linked with the Pyrenean compressive events through their ages and their “subbriançonnais” structural position. Sedimentological, mineralogical (heavy minerals), and geochemical analysis, point to a potential “Pyrenean signature” which would testify the Late Cretaceous collision between the Ibero-Briançonnais terrane and the European plate. A “Dauphinois” origin and basin inversion erosion is proposed for the zircon-tourmaline-rutile (ZTR) bearing Piolit flysch, deposited from the Coniacian to the Campanian. A Penninic origin with tectonic inversion and erosion of former tilted blocks of the European margin from the Turonian to the Paleocene is proposed for the ZTR bearing Pelat flysch. Comparison with the Niesen (Swiss Prealps) and La Ciotat (Provence) flysch depositional context, allows to better constrain the Pyrenean compressive event in the Alpine domain. The Senonian part of the Baiardo flysch, that contains a garnet-dominated heavy mineral association and distinct geochemical trends, is allotted to the Liguro-Piemontais domain and to the Alpine collision stricto sensu.

Interspecific Association of Heavy Minerals in Late Paleozoic Gondwana Sandstones of Singrauli Sub-basin, Central India: Implications for Provenance

Abstract: Heavy mineral analysis of the late Paleozoic Barakar and Raniganj sandstones from the Singrauli Gondwana sub-basin shows relative abundance of garnet, epidote, zircon, tourmaline and muscovite in the Raniganj Sandstone and epidote, garnet, rutile and tourmaline in the Barakar sandstones. Stratigraphically, the heavy mineral crops donot exhibit marked variation in their relative abundance, though garnet, epidote and muscovite form the bulk of the heavy minerals. Significant interspecific association among heavy minerals and provenance of the Barakar and Raniganj sandstones are evaluated by using σ -M multivariate model. Quantitative result suggests that the Barakar Sandstone are characterized by the basic pair match significantly more than expected due to chance alone (p value <<0.05) are garnet-tourmaline and epidote-rutile, whereas, the succeeding Raniganj sandstone are characterized by zircon-rutile and epidote-garnet. These basic pairs may be regarded as interspecific association among the heavy minerals. The basic pairs deduced from heavy mineral suites suggest that the source rocks of late Paleozoic Barakar and Raniganj sandstones have been principally derived from the acid plutonic rocks and low to high grade metasediments lying to the south and southeast of the Singrauli Gondwana sub-basin.

Heavy–mineral assemblages from fluvial Pleniglacial deposits of the Piotrków Plateau and the Holy Cross Mountains – a comparative study

Abstract The heavy-mineral assemblages of Pleniglacial fluvial sediments were analysed for two river valleys, viz. the Luciąża River (at Kłudzice Nowe) and the Belnianka River (at Słopiec). These sites, on the Piotrków Plateau and in the Holy Cross Mountains respectively, are located in different morphogenetic zones of Poland that were affected to different degrees by the Middle Polish ice sheets. The study was aimed at determining the kind of processes that modified the heavy-mineral assemblages in the two fluvial sediments, at reconstructing the conditions under which these processes took place, and in how far these processes caused changes in the assemblages. The heavy-mineral associations of the parent material was taken as a starting point; this parent material were the sediments left by the Odranian glaciation (Warta stadial = Late Saalian). It was found that heavy-mineral assemblages in the Luciąża valley deposits are varied, particularly if compared with other fluvioglacial Quaternary deposits from the Polish lowlands, with a dominance of garnet. In the fluvial deposits of the Belnianka valley, zircon, staurolite and tourmaline dominate, with minor amounts of amphibole, pyroxene, biotite and garnet. This suggests that the deposits were subject to intensive and/or persistent chemical weathering and underwent several sedimentation/erosion cycles under periglacial conditions. In both valleys chemical weathering and aeolian processes were the main factors that modified the assemblages of the transparent heavy minerals; these processes were largely controlled by the climatic changes during the Pleistocene.

Karst bauxites in the Campania Apennines (southern Italy): a new approach

In this study new data on two bauxite districts in the Campania region (southern Italy) are reported: the Matese Mts. and the Caserta province, exploited in the first part of the XX century. The nature and distribution of diagenetic and detrital mineral phases were investigated by means of transmitted-light and scanning electron (SEM) microscopy, X-ray powder diffraction (XRPD) and energy dispersive spectroscopic microanalysis (EDS), whole-rock geochemical analyses (ICP-OES and ICP-MS), complemented by preliminary QEMSCAN ® investigation. The textures of the bauxite ore range between oolitic and oolitic-conglomeratic and arenitic. Boehmite is the most abundant phase, while other Al-bearing phases (gibbsite and diaspore) are very subordinate. The Fe-minerals hematite, goethite and lepidocrocite occur, and Ti-minerals anatase and rutile are ubiquitous. Among clay minerals, kaolinite is prevailing at the Regia Piana (Matese Mts.) and illite-montmorillonite in the Caserta province. Most recorded trace minerals are quartz, calcite, zircon and monazite. Small clusters of not previously detected qandilite [(Mg, Fe 2+ ) 2 (Ti, Fe 3+ , Al) O 4 ], and of hercynite-type spinels also occur. By means of QEMSCAN ® it has been possible to better recognize some diagenetic textures (e.g. mainly matrix- or ooids-supported bauxite, the clay/Al-hydroxides distribution etc.) and to detect other detrital minerals (feldspar, muscovite, olivine, titanite and possibly a serpentine/talc-like phase). A similar detrital mineral association has been found also in the Aptian “Orbitoline ” marls, which are marine sediments supposed to be the non-weathered equivalent of bauxites. Very detailed data about major, minor and trace element (comprising “bauxitophile ” and REEs) concentrations and some significant geochemical ratios are reported for the bauxite samples, and a new interpretation on the possible source of the parent material has been proposed. The detrital heavy mineral association may suggest not only a windblown volcanic source material (Dinarides explosive volcanism?), as hypothesized in literature, but also a partial origin from an exposed terrain. The exact nature and paleogeographic position of this source could not be determined by chemical analyses of major and trace elements (including REE), Eu/Eu* and TiO 2 /Al 2 O 3 ratios and Ni-Cr contents. However, due to the isolated position of the Appennine carbonate platform during the Cretaceous, the paleogeographic model precludes any possible fluviomarine transport for the source material (windblown?) of the bauxites.

Mineralogical and geochemical characteristics of Quaternary sediments from the Island of Susak (Northern Adriatic, Croatia)

Middle and Upper Pleistocene loess–palaeosol sequences up to 90 m thick are exposed on the Island of Susak located in the Northern Adriatic Sea in Croatia. During glacial times the sea level was up to about 120 m lower and a significant part of the Adriatic became land. The source area of the primary aeolian sediments was in the vicinity of the island and is related to the southward extended River Po plain. The loess has a mainly clayey to sandy silt or sand grain-size and is intercalated by at least three tephras, numerous palaeosols and calcareous segregations. The heavy mineral association points to metamorphic and igneous rocks from Alpine regions as source material of the loess. Geochemical and mineralogical properties of loess and palaeosols differentiate one from another and reflect the intensity of weathering and pedogenesis. The oldest tephra contains vitroclasts and serrated clinopyroxene while the middle and the youngest tephra along with vitroclasts, contain idiomorphic augite as diagnostic volcanic features. Based on bulk rock and vitroclast chemistry, morphology of pyroxenes, and the age of the loess sandwiching the tephra, the potential source of this volcanic material could very likely be the Campanian or Aeolian volcanic province in southern Italy. Infrared stimulated luminescence dating-results show that the major part of the aeolian deposits including the tephra layers correlates to MIS 3–MIS 5.