Heavy Mineral Analysis Research Articles

A study on textural characteristics, heavy mineral distribution and grain-microtextures of recent sediment in the coastal area between the Sarada and Gosthani rivers, east coast of India

The current study aimed to describe textural characteristics, heavy mineral composition, and grain microtextures of the sediment from three micro-environments (foreshore, berm, and dune). A total of forty-one (41) representative surficial sediment samples have been collected from fifteen (15) locations along the beach area between the Sarada and Gosthani rivers on the east coast of India, where the length of the stretch is more than 100 km. The study reveals that most of the coastal sediment is medium to fine sand with relatively high ratios of coarse sand at Yarada beach, and the nature of the sediment is moderately to well sorted. These characteristics indicate a high energy environment. The heavy mineral analysis of the sediment in the current study was done for coarse (+60#) and fine (+230#) size fractions. Studying the weight percentage (WT%) reveals that a high percentage of heavy minerals is associated with fine fractions. Ilmenite, sillimanite, garnet, zircon, and rutile are the major heavy minerals identified in the current investigation. The concentrations of these heavy minerals show great variations from south to north of the study area. From an economic point of view, a considerable amount of heavy minerals (average 48.41%) are present on both sides (north and south) of the Gosthani River mouth. In the Sarada Estuary, the concentration of the economic heavy minerals was found under the minimum economic range. The grain microtextures of the major heavy minerals from the different locations along the study area demonstrate the variation in grain microtextures, which is controlled by the chemical and mechanical processes. These microtextures reflect moderate to high wave energy on the beach area, in addition to high mechanical impact on the grains from the estuary point.

Controls on Early Cretaceous desert sediment provenance in south‐west Gondwana, Botucatu Formation (Brazil and Uruguay)

AbstractThe Lower Cretaceous Botucatu Formation records the development of widespread dry–aeolian desert sedimentation throughout the Paraná Basin in south‐west Gondwana. To reconstruct the provenance of the aeolian sediment, petrography, granulometric analysis, U‐Pb detrital zircon ages have been determined from along the southern basin margin in Rio Grande do Sul state (southern Brazil) and Uruguay (Tacuarembó region). The dataset reveals a mean composition Qt89F8L3, comprising very fine to medium‐grained quartozose and feldspatho‐quartzose framework. Heavy mineral analysis reveals an overall dominance of zircon, tourmaline and rutile grains (mean ZTR0.84) with sporadic garnet, epidote and pyrolusite occurrences. The detrital zircon U‐Pb ages are dominated by Cambrian to Neoproterozoic (515 to 650 Ma), Tonian to Stenian (900 to 1250 Ma) and Orosirian to Rhyacian (1.8 to 2.2 Ga) material. The detrital zircon dataset demonstrates a significant lateral variation in sediment provenance: Cambrian to Neoproterozoic detrital zircons dominate in the east, while Tonian to Stenian and Orosirian to Rhyacian ages predominate in the west of the study area. Sandstones are quartz‐rich with dominantly durable zircon, tourmaline and rutile heavy mineral suite, with subtle but statistically significant along‐strike differences in heavy mineral populations and detrital mineralogy which are thought to record local sediment input points into the aeolian system. The similar age spectra of Botucatu desert with proximal Paraná Basin units, the predominance of quartzose, and zircon, tourmaline and rutile components, suggests that recycling is the mechanism responsible for the erg feeding.

Heavy Mineral Composition and Sources of Himalayan Neogene Sediments Occurring along the Garu-Likabali Road Section, West Siang District, Arunachal Pradesh, India

The Neogene sedimentary sequence of the Arunachal Himalayas is represented by the Dafla, Subansiri and Kimin Formations. Their systematic heavy mineral analysis along the Garu-Likabali Road section indicates that the heavy mineral assemblage is composed of fifteen heavy mineral varieties comprising of andalusite, biotite, chloritoid, chlorite, epidote, garnet, hornblende, hypersthene, kyanite, muscovite, rutile, sphene, staurolite, tourmaline and zircon, besides opaque minerals. The assemblage points towards a complex sediment provenance for the Neogene sedimentary sequences with sediment inputs from pre-existing igneous, metamorphic and sedimentary rocks. The boundary between the Dafla and Subansiri Formation in the region can be demarcated on the basis of disappearance of Hypersthene in the heavy mineral suite of the older Dafla Formation as well as appearance and persistence of staurolite in the same Formation.

MINERALS AND SEDIMENTARY CHARACTERISTICS OF QUATERNARY SEDIMENTS OF DIFFERENT REGIONS IN SOUTHERN IRAQ

This study tries to evaluate the sediments of Quaternary deposits with a depth from 8 to 24 meters, and determine the lights and heavy minerals with their origin. Three boreholes; Basrah, Thi-Qar and Missan, were selected, based on the grain size analysis of samples, three types of sediment were identified: silt, sandy silt, and silty sand. The statistical size parameters were applied to determine the energy and sedimentation environment, showed that the sediments of the study area were deposited in low-energy conditions. The sorting values ranged from poorly to very poorly, while the skewness ranged from strongly fine to near symmetrical skewed and kurtosis values ranged from platy to leptokurtic. The results of heavy minerals analysis proved the very low values comparative with light ones; Opaque was predominant in all study sites, accounting for about 50% of the heavy minerals and divided to mica minerals and Chlorite, Pyroxene, Amphibole, Zircon, Epidote, and Garnet, while Kyanite, Tourmaline and Staurolite. The light minerals are dominated by carbonate and quartz with few amounts of chert, evaporates, Feldspar, rock fragments and light muscovite. The difference in the values and diversity of heavy minerals in the study area indicates the multiple sources contributing to the deposits of the Mesopotamia Plain. The sources are limited between the rivers of Tigris, Euphrates and Shatt Al-Arab and the dust-fallouts, as well as the nearest formations and the Arabian shield.

A Comparative Study of Different Machine Learning Algorithms in Predicting the Content of Ilmenite in Titanium Placer

In this study, the ilmenite content in beach placer sand was estimated using seven soft computing techniques, namely random forest (RF), artificial neural network (ANN), k-nearest neighbors (kNN), cubist, support vector machine (SVM), stochastic gradient boosting (SGB), and classification and regression tree (CART). The 405 beach placer borehole samples were collected from Southern Suoi Nhum deposit, Binh Thuan province, Vietnam, to test the feasibility of these soft computing techniques in estimating ilmenite content. Heavy mineral analysis indicated that valuable minerals in the placer sand are zircon, ilmenite, leucoxene, rutile, anatase, and monazite. In this study, five materials, namely rutile, anatase, leucoxene, zircon, and monazite, were used as the input variables to estimate ilmenite content based on the above mentioned soft computing models. Of the whole dataset, 325 samples were used to build the regarded soft computing models; 80 remaining samples were used for the models’ verification. Root-mean-squared error (RMSE), determination coefficient (R2), a simple ranking method, and residuals analysis technique were used as the statistical criteria for assessing the model performances. The numerical experiments revealed that soft computing techniques are capable of estimating the content of ilmenite with high accuracy. The residuals analysis also indicated that the SGB model was the most suitable for determining the ilmenite content in the context of this research.

Sedimentological Characterization of Alluvial Gold Deposits of Betrare-Oya and Its Surroundings (Cameroon Eastern Region)

Sedimentological methods such as granulometry, morphoscopy and heavy minerals analysis have been carried out to characterize alluvial gold deposits of Betare-Oya and its surroundings, with the aim to determine their origin and conditions in which they are formed and also to determine the mineralogical content of these deposits, their nature and distribution. It came out from this study the following: The alluvial deposits studied are sand, constituting of coarse fraction (grains), medium grains in abundant and fine grains. The average values of sorting index (S0) and coefficient of asymmetry (A) are respectively 2.53 and 0.73. These values indicate that the sand is poorly arranged and poorly sorted with a better classification or arrangement in the coarse fraction (grains). These are sediments that are deposited together by high competent currents. It would therefore probably be torrential deposits and or streams from short transport. Unused grains are dominating (80.5%) which translate a proximal source of the sediments. So it would be probably from the dismantling of the surrounding landforms. The heavy minerals studied revealed the presence of the following minerals; zircon, gold, sphene, green hornblende, tourmaline, rutile, augite, hypersthene, sillimanite, glau-cophane, biotite, staurotide, and the opaque. These minerals belong to the cortege of plutonic and metamorphic rocks from a single proximal distributing province.

Stratigraphy and conditions of accumulation of the Younger Loesses (Vistulian) in the Holy Cross Mountains area, Poland

The paper presents results of studies focused on occurrence and correlation of four main horizons of Younger Loesses: Lowest Younger Loess (LMn – after Maruszczak, 2001), Lower Younger Loess (LMd), Middle Younger Loess (LMs), and Upper Younger Loess (LMg) recorded in five sections (Politów, Wąchock, Nietulisko Małe, Komorniki and Bodzechów) in the Holy Cross Mountains area. All analysed loesses were accumulated during the Vistulian Glaciation (Weichselian). The horizons were distinguished based on separating interstadial tundra soils, coupled with thermoluminescence dating, and correlated with marine oxygen-isotope stages MIS 5d−2. The Lowermost Younger Loess (LMn) covers the Nietulisko I soil complex (Jersak, 1973), developed on deposits of the Odranian Glaciation (MIS 6) and representing a forest soil of the Eemian Interglacial (MIS 5e) and the Brørup warming (MIS 5c). A thin horizon of the Oldest Younger Loess and a thin sandy horizon, both probably corresponding to the Herning cooling phase (MIS 5d) at the boundary with the Eemian Interglacial, were distinguished within this complex. Based on previously performed grain-size and heavy mineral analysis of the Upper Younger Loess (LMg) and a topographic position of the loesses in four loessy islands of diverse regional extent, accumulation of this loess in the Holy Cross Mountains area is found to have been stimulated by the western winds. The proposed model of loess accumulation takes into account the influence of the topography of the area and its geological structure.

The response of a dune succession from Lençóis Maranhenses, NE Brazil, to climate changes between MIS 3 and MIS 2

In tropical Southern Hemisphere South America, late Quaternary marine core and speleothem records provide different proxies and accurate chronologies correlating millennial-scale intervals of increased precipitation with southward shifts of the Intertropical Convergence Zone (ITCZ). However, the climatic effect of these intervals on coastal landforms is poorly understood. Here we investigated the response of abrupt and long-lasting climate events during the Marine Isotope Stages 3 and 2 in a 13.8-m thick sand succession located in a large-scale coastal eolian system, the Lençóis Maranhenses Dunefield, NE Brazil, where winds and precipitation are anti-phased and controlled by the single action of the ITCZ. A chronology of the sediment overburden determined by optically stimulated luminescence (OSL) dating of 14 sediment samples obtained at 1-m intervals showed ages between 132.2 ± 7.0 and 12.9 ± 0.6 thousand years ago in stratigraphic order. A multi-proxy approach based on grain size, surface grain texture, heavy minerals, thermoluminescence (TL) sensitivity, inorganic geochemistry, reflectance, and magnetic parameters from 268 sediment samples collected at 5-cm intervals indicated periods of dune building and stabilization. Significant stabilization periods are synchronous with Heinrich Stadials 6, 4, 3, 2, and 1, and Greenland Stadial 4, within age model uncertainties. Heavy mineral analysis indicated a steady sand source to the dune succession, while TL sensitivity analysis of quartz grains showed the input allochthonous sediments during stadials. The preservation of peak dune activity during the Last Glacial Maximum is attributed to the enduring precipitation brought by the subsequent Heinrich Stadial 1 event.

Provenance of Eocene–Oligocene sediments in the San Jacinto Fold Belt: Paleogeographic and geodynamic implications for the northern Andes and the southern Caribbean

AbstractMesozoic and Cenozoic strata of the San Jacinto Fold Belt (Colombian Caribbean) provide insights about sedimentary environments and paleogeographic evolution in the transition between the northern Andes and the South Caribbean deformed belt. We report new provenance (conventional sandstone petrography, heavy mineral analysis, and detrital zircon U-Pb geochronology and typology) and micropaleontologic data (palynology, calcareous nannofossils, and foraminifera) in samples collected from the lower Eocene (San Cayetano Formation) and upper Eocene–Oligocene (Toluviejo and Ciénaga de Oro Formations) rocks in boreholes drilled by the Colombian Agencia Nacional de Hidrocarburos as well as from recently exposed Oligocene outcrops from the Ciénaga de Oro Formation. Sandstone petrography shows modal variations, with high feldspar content in the lower Eocene rocks and high quartz content in the Oligocene deposits. This shift in compositional maturity may be due to climatic variations, tectonic activity, and/or changes in source areas. Heavy mineral analyses indicate variations that suggest sources primarily related to felsic igneous and/or low-grade metamorphic and mafic and ultramafic rocks. Zircon U-Pb geochronology displays age populations mainly in the Late Cretaceous, Late Jurassic, Permian–Triassic, and Precambrian (ca. 900–1500 Ma). In addition, zircon typology analyses indicate that the igneous zircons came primarily from monzogranites and granodiorites. Finally, the micropaleontologic and sedimentary data sets indicate that the sediments were deposited in tropical coastal and shallow marine environments. The sediments were transported by short rivers from the crystalline massifs of the Lower Magdalena Valley and the northern Central Cordillera basements, while distal transport of sediments may have occurred along longer rivers, which brought sediments from southern regions located between the Central and Western Cordilleras.

Provenance of Upper Pennsylvanian siliciclastic‐carbonate deposits from the Monte Alegre and Itaituba formations, North Brazil: An integrated study of sandstone petrography, heavy mineral analysis and garnet geochemistry

The Monte Alegre and Itaituba formations record the transition from a fluvial‐aeolian to a carbonate platform system during the Pennsylvanian on the southern margin of the Amazonas Basin, North Brazil. Sandstones of these formations were analysed for their petrofacies, provenance, tectonic configuration and diagenetic history to determine their origin. The Monte Alegre sandstones are fine‐ to medium‐grained, well‐sorted, bimodal quartz‐arenites with a normal grain‐supported framework of straight and concavo‐convex contacts. They present 97% of ZTR (zircon‐tourmaline‐rutile) heavy minerals. The Itaituba sandstones are fine‐ to very fine‐grained, well‐sorted, sub‐arkoses with an open to normal framework supported by carbonate cement. The heavy minerals are represented by zircon, tourmaline, rutile, kyanite and garnet, with almandine and pyrope as the main types derived from high‐grade amphibolite‐ to‐ granulite‐facies metasediments, in addition to intermediate‐acidic igneous rocks. The petrofacies analysis revealed that the sandstones of these formations belong to the tectonic regime of the continental block, Interior Craton. The Amazonas Basin basement on the southern edge consists of intrusive suites and cratonic rocks of the Tapajós and Iriri‐Xingu provinces, which are represented by the Cuiú‐Cuiú Complex and the Iriri Group. These groups of rocks were the main sources of sandstones of these formations. This conclusion indicates that these rocks were uplifted, exposed and eroded during and/or after the Middle Carboniferous. The imprints of early and deep burial diagenesis of these sandstones, including different stages of compaction, cementation and heavy minerals elimination, produced differences in sandstones porosity and heavy minerals assembly.

Jurassic–Early Cenozoic Tectonic Inversion in the Qilian Shan and Qaidam Basin, North Tibet: New Insight From Seismic Reflection, Isopach Mapping, and Drill Core Data

AbstractThe pre‐Cenozoic structural pattern of Asia has had a strong impact on the localization and propagation of the Cenozoic deformation that gave birth to the Tibetan Plateau. Northern Tibet represents a key area to decipher the structural and kinematic links between the Mesozoic and Cenozoic evolution of Tibet. Nonetheless, the Mesozoic tectonic setting of the North Tibet and the role that the Paleozoic inherited Altyn Tagh Fault (ATF) shearing zone played in controlling the regional tectonic pattern during the deposition of the Mesozoic strata remain controversial. This study is based on seismic reflections, isopach maps of the Mesozoic strata in the Qaidam Basin, and provenance analysis using detrital zircon geochronological and heavy mineral contents. Seismic reflections and isopach maps demonstrate that sustained strike‐slip motion along the ATF during the Early to Late Jurassic induced transtensional basin formation. Further away from the main ATF (eastern parts of the Qilian Shan and the northern Qaidam Basin), transtension also occurred along major faults, although local transpression developed in relay zones. Rotation in the regional stress field induced compression and basin inversion during the Late Jurassic to Early Cretaceous. The Cenozoic sedimentary rocks in these regions display widespread growth strata and angular unconformities characteristic of compression. This is consistent with topographic changes marked by sediment source variation evidenced by detrital zircon geochronology and heavy mineral analysis. We propose that the mechanism driving the Jurassic extension/transtension in North Tibet could be related to far‐field effects of subduction processes along the southern margins of the continent.

Integrating heavy-mineral, geochemical and biomarker analyses of Plio-Pleistocene sandy and silty turbidites: a novel approach for provenance studies (Indus Fan, IODP Expedition 355)

AbstractA multidisciplinary mineralogical, geochemical and biomarker study of Indus Fan sediments cored during International Ocean Discovery Program (IODP) Expedition 355 to the Laxmi Basin was carried out to define the different compositional signatures of sand, silt and clay. Upper Pliocene – lower Pleistocene turbidites from sites U1456 and U1457 were selected as the best candidates for this study. The integrated dataset presented here was obtained by coupling traditional and innovative bulk-sediment and single-mineral techniques on the same samples. Turbiditic deposits mostly consist of medium to fine silt, including rich and diverse heavy-mineral assemblages. Such a fine grain size forced us to push the limits of high-resolution quantitative heavy-mineral analysis down to as low as 5 μm. Heavy-mineral analysis allowed us to establish a Himalayan origin of the detritus in the studied turbidites. Heavy-mineral concentrations are higher in channel-fill than in overbank deposits. Mineralogical and geochemical data concur in revealing that fast-settling ultradense minerals such as zircon are preferentially concentrated in channel-fill deposits, whereas the top of overbank deposits are notably enriched with slow-settling platy phyllosilicates. Biomarker analysis represents a most suitable complementary technique that is able to investigate the provenance signature of the finer sediment fraction, largely consisting of clay. This technique allowed us to identify a largely terrigenous origin of organic matter at Site U1456 and an open marine origin at Site U1457. The latter site lies closer to the Laxmi Ridge, where thermal maturity increases with depth to reach the early oil window (127°C at c. 320 m below the seafloor).

Sand source and formation mechanism of riverine sand dunes: a case study in Xiangshui River, China

Riverine sand dunes develop as a result of fluvial-aeolian interactions. The primarily barchan dune chains along the Xiangshui River (a branch of the Xar Moron River in the western part of the Horqin Sandy Land of China) form a typical riverine dune field. We collected a series of samples from the riverine sand dunes parallel to the direction of the prevailing wind and investigated the sand sources and formation mechanisms of these dunes by determining the grain size, heavy mineral content and optically stimulated luminescence (OSL) of the samples. The sand of the near-river dunes was coarser than the sand of the dunes distant from the river, indicating that coarse sand of the valley mainly deposited on near-river dunes. The heavy mineral analysis suggested that wind-sand activity levels were intense on the upwind dunes, but relatively weak on the downwind dunes. This indicated that the sand sources for the near-river dunes were more abundant than those of the distant dunes. Our OSL analysis of samples suggested that the deposition rates on dunes near the river were greater than the deposition rates on dunes distant from the river. The development of dunes along the river indicated that the river played an important role in dune formation and development. In addition, airflow fluctuation and the formation of the waveform dunes had a type of feedback relationship. Grain size, heavy mineral and OSL analyses are widely used methods in wind-sand research. Sand dune grain size characteristics reflect the effects of airflow on the transport and separation of sand materials, as well as the physical characteristics of the sand sources. Heavy mineral characteristics are often used to investigate the relationships between sediments and sand sources. OSL indicates dune age, revealing formation of dunes. Therefore, it is useful to explore dune sand sources, as well as the mechanisms underlying dune formation, by determining grain size, heavy mineral content and OSL. This study investigated the sand sources of riverine dunes and provided new information about riverine dune formation and development.

Semi-Automated Heavy-Mineral Analysis by Raman Spectroscopy

A significant amount of information on sedimentary provenance is encoded in the heavy minerals of a sediment or sedimentary rock. This information is commonly assessed by optically determining the heavy-mineral assemblage, potentially followed by geochemical and/or geochronological analysis of specific heavy minerals. The proposed method of semi-automated heavy-mineral analysis by Raman spectroscopy (Raman-HMA) aims to combine the objective mineral identification capabilities of Raman spectroscopy with high-resolution geochemical techniques applied to single grains. The Raman-HMA method is an efficient and precise tool that significantly improves the comparability of heavy-mineral data with respect to both overall assemblages and individual compositions within solid solution series. Furthermore, the efficiency of subsequent analysis is increased due to identification and spatial referencing of the heavy minerals in the sample slide. The method is tested on modern sediments of the Fulda river (central Germany) draining two Miocene volcanic sources (Vogelsberg, Rhön) resting on top of Lower Triassic siliciclastic sediments. The downstream evolution of the volcanic detritus is documented and the capability to analyze silt-sized grains has revealed an additional eolian source. This capability also poses the possibility of systematically assessing the heavy-mineral assemblages of shales, which are often disregarded in sedimentary provenance studies.

Heavy mineral analysis of Eocene sands and sandstones of Nanka Formation, Cenozoic Niger Delta petroleum province

ABSTRACT The heavy minerals present in lithologic sand and sandstone units of Nanka Formation are mainly zircon, rutile, tourmaline, apatite, staurolite, and opaque minerals (Goethite, hematite, ilmenite), which are present dominant in weathered sandstones when analysed using petrographic varietal studies to infer provenance, diagenesis and source area weathering history. The low-diversity and relative abundance of heavy mineral assemblages are controlled by provenance and diagenetic processes, and these present limitations in accurate reconstruction of the paleo-history of these lithologic units using heavy minerals analysis alone. These lithologic Eocene units are derived from intensely weathered granitic and metamorphic source rocks and they are composed dominantly of matured polycyclic sediments.

Sedimentological and provenance analysis of the Río Playas stratigraphic section: Implications for the evolution of the Alamor-Lancones Basin of southern Ecuador and northern Peru

The Cretaceous Alamor-Lancones Basin is located in the forearc region of southern Ecuador and northern Peru. The eastern (Río Playas) domain includes the upper stratigraphic levels of the 1800 m thick basin-fill succession. Sedimentological, provenance and chronostratigraphic analyses of the Río Playas region help to elucidate the Late Cretaceous to Eocene evolution of the forearc region in southern Ecuador and neighboring regions.The oldest strata of the Río Playas region include Lower Cretaceous volcanic and volcaniclastic deposits of the Celica and Alamor formations, which were deposited in an arc-related extensional basin. These units are unconformably overlain by the Coniacian to Maastrichtian El Naranjo and Casanga formations. Lithofacies described for the El Naranjo and Casanga formations include sandy debrites, sandy turbidites, silty-muddy turbidites, sandy slumps, clast-supported debrites and rafted blocks. These lithofacies association suggests a deepwater submarine fan depositional environment.Provenance analyses for the Casanga and El Naranjo formations, including heavy mineral and petrographic data, show that these formations were derived from erosion of a volcanic arc and a minor granitic and metamorphic source terrane. Detrital zircon U-Pb ages for the Casanga Formation indicate contributions from Santonian age sources, which partially overlap stratigraphic ages, suggesting volcanism contemporaneous with deposition. In addition, paleocurrent analyses indicate sediment transport to the southeast, pointing to a sediment source along the South American margin.Volcanic and volcaniclastic rocks of the Paleocene Sacapalca Formation overlie the Casanga and Naranjo formations in angular unconformity. The Sacapalca Formation passes transitionally into fluvial sandstone, conglomerate and red beds of the Río Playas Formation. Overall, the succession recorded a transition from volcanic to alluvial fan deposition. Heavy mineral and sandstone QFL analyses show a significant input of metamorphic detritus in the Río Playas Formation, which indicates derivation from the Cordillera Real. This interpretation is also supported by detrital zircons of Proterozoic age. The change from submarine fan deposits of the El Naranjo and Casanga formations to the nonmarine Río Playas Formation suggests exhumation in response to an important tectonic event, likely deformation related to collision of the Caribbean Plateau to South America at 73–70 Ma.

Provenance studies of aeolian sand in Mu Us Desert based on heavy-mineral analysis

Provenance studies of aeolian sand are beneficial for understanding desert formation and evolution. The material source of aeolian sand in the Mu Us Desert remains controversial, and few studies have focused on its sand transport pathways. Thus, the heavy-mineral compositions of 92 modern aeolian sand samples, 23 fluvio-lacustrine sediment samples, 5 alluvial sediment samples and 19 bedrock samples were examined in this study. First, aeolian sand samples were classified into several groups by assemblage-based hierarchical cluster analysis. Then, the mineralogy of each group was compared with potential source mineralogies to determine the groups’ origins. Finally, the dune sands’ transport pathways were determined by comparing the between-assemblage similarities of sands along the wind direction. The results reveal the following: (1) The aeolian sand heavy-mineral suites in the central and northern areas differ from those in the southwestern areas, suggesting significant source differences. In the central and northern areas, the weathered detritus of sandstone was concentrated in depressions mainly by fluvial processes, thus providing a primarily fluvio-lacustrine sediment supply for dune creation. In the desert’s southwestern region, the sources also include Yellow River sediment and Loess Plateau slopewash. (2) The sand transport is strongly limited by fluvial and lacustrine systems, leading to anisotropic suite patterns in aeolian sand in the Mu Us Desert.

OH in detrital quartz grains as tool for provenance analysis: Case studies on various settings from Cambrian to Recent

Detrital quartz grains from Paleozoic and Mesozoic sandstones from North Africa and central Europe, respectively, and from recent siliciclastic sediments of the Elbe River from Germany were analysed by IR spectroscopy with respect to their OH defect content. Sample sets were carefully chosen to cover different stratigraphic units from different localities and according to previous findings that indicate a significant change in the source region in the respective sedimentary system. The validity of the new method is compared to heavy mineral and zircon age spectra analysis from previous studies. Results reveal that the OH defect inventory in quartz shows in all investigated sedimentary successions significant internal variations from sample to sample and thus may be used as a tool to identify changes in the source region. The degree of changes observed with the new method does not necessarily reflect the magnitude in differences observed by other methods (such as heavy minerals and/or zircon age spectra), underlining the potential as complementary tool for provenance analysis. The new tool is also tested to estimate mixing proportions between the Variscan and the Scandinavian signal in the Elbe River, resulting in a surprisingly high contribution of the Nordic source.

Climate and tectonic-driven deposition of sandwiched continental shale units: New insights from petrology, geochemistry, and integrated provenance analyses (the western Sichuan subsiding Basin, Southwest China)

How the depositional setting efficiently governs the characteristic sandwiched continental shale units remains uncertain, which restricts an integrated assessment of organic-rich fluvio-lacustrine shale reservoirs, and accurate estimation of potential natural gas resources. Here, we present new results from petrological observations, element geochemical fingerprinting, and integrated analyses of heavy mineral, basinal subsidence history, and sandstone / stratum ratio on typical and terrigenous sandwiched-like depositional systems of the targeted Upper Triassic Xujiahe Formation in the western Sichuan subsiding Bain, Southwest China. In view of the representative and environment-sensitive indices, we suggest that passive continental margin and continental island arc dominated by granite to granodiorite source are the major tectonic settings of the provenance, and both a more warm-humid climate characterized by intensified chemical weathering conditions and a calm tectonically quiescent setting are identified as two major drivers forcing the accumulation and preservation of organic matter in organic-rich continental shale units. Finally, a comprehensive depositional model is established for providing new insights into the linkage between palaeoclimatic conditions, tectonic pulses and terrigenous clastic sedimentation. Both the cyclic palaeoclimate fluctuations and episodic tectonic activities are believed to have exerted a very considerable force on development of the unique sandwiched-like stratigraphic framework, and the coupling interactions between the tectono-climatic evolution and fine-grained sedimentation are thus also stressed.

The Use of Heavy Minerals in the Investigation of Barrier-Lagoon Coasts Development in Dapeng Peninsula, China

Typical barrier-lagoon systems are developed at Dongchong and Xichong on the southern coast of the Dapeng Peninsula of Guangdong, China. This paper studies the evolution of the barrier coasts of the peninsula, using the examples of the Dongchong and Xichong Bays. The Holocene stratigraphic records from borehole drilling on the coast of Dongchong and Xichong show that lagoon sediments are overlaid with beach deposits, indicating that the barriers migrated landward and climbed over the lagoon sediments when the shoreface retreated during the Holocene transgression, reaching the present positions after 7–8 ka BP. Heavy mineral analysis in this paper shows that: (1) the ancient beach sediments of the two bays have the same heavy mineral assemblages, which are different from those of modern beaches; (2) the present beaches of the two bays have different heavy mineral assemblages, even they are located less than 3000 m from each other on the same coast. This supports the hypothesis that the barriers originally came from the inner shelves during the Holocene transgression, but draws a new conclusion that the source of the beach sediments changed to inland rivers over the last thousand years because of a lack of sediment source from the sea floor.