Quartz-rich Sand Research Articles

Quartz arenites as signatures of cratonisation: examples from the Archaean Stratigraphic Record, southern Africa

Abstract Holocene quartz-rich sands such as in the Orinoco River of Venezuela and Columbia, develop under a unique set of conditions including tectonic stability, intense weathering and long-term storage of sediment prior to burial. This review paper proposes that a similar set of conditions existed on the Mesoarchaean Earth by 3.0 Ga. Compositionally and texturally mature quartz arenites are present in the Mesoarchaean Hospital Hill Subgroup and correlative lower Mozaan Group, in the cover rocks of the Beitbridge Complex in the Limpopo Belt and at Buhwa in southern Zimbabwe as well as the Neoarchaean Manjeri Formation of Zimbabwe. These quartz arenites are interpreted as first-cycle and developed following the formation of stable cratons under conditions of slow subsidence (<10 cm/1 000 years), intense weathering in a hostile chemical environment related to the ambient carbon dioxide-rich atmosphere, long-distance intrabasinal transport by tides and/or waves and microbial processes that influenced the local chemical environment. Similar examples of Mesoarchaean quartz arenites are documented from the Yilgarn Block in Western Australia, the Slave and Superior provinces in Canada and the Dharwar and Singhbhum cratons in India. On a global scale, cratonisation was diachronous with the Kaapvaal Craton stabilised on a regional scale by 3.0 Ga whereas microcontinents existed over the remainder of Earth.

Effects of Carbonic Acid-Rock Interactions on CO2/Brine Multiphase Flow Properties in the Upper Minnelusa Sandstones

SummaryCarbon dioxide (CO2) injection into a deep saline aquifer can dissolve into formation brine and generate carbonic acid. The resulting acid can drive fluid-rock geochemical reactions. The impact of these fluid-rock geochemical reactions on porosity, permeability, and multiphase flow responses is relevant to the determination of CO2 storage capacity of deep saline aquifers. In this research, carbonic acid flooding experiments were performed on core samples consisting of poorly sorted, quartz-rich sand with laminated bedding from a possible CO2 storage target in northwest Wyoming. Complementary pre- and post-injection porosity and permeability, thin-section, Brunauer-Emmett-Teller (BET) surface area, mercury intrusion capillary pressure (MICP), and time-domain nuclear magnetic resonance (TD-NMR) measurements were conducted. Overall, both core porosity and permeability increased after a 7-day carbonic acid injection, from 6.2 to 8.4% and 1.6 to 3.7 md, respectively. We attributed these changes to carbonate mineral dissolution, which was evidenced by the effluent brine geochemistry, pore-throat size distribution (PTSD), and BET surface area. To be more specific, within the more-permeable section of core samples containing larger pore size, the permeability increment is apparent due to dolomite mineral grains and cements dissolution. However, for the lower-permeability section corresponding to the smaller pore size, mineral precipitation possibly lessened dissolution effects, leading to insignificant petrophysical properties changes. Consequently, the observed heterogeneous carbonic acid-rock interactions resulted in alterations of CO2/brine relative permeability (i.e., the initial CO2 saturation decreased and the CO2 flow capacity was enhanced). This research provides a fundamental understanding regarding effects of fluid-rock reactions on changes in static and multiphase flow properties of eolian sandstones, which lays the foundation for more accurate prediction/simulation of CO2 injection into deep saline aquifers.

The relevance of coastal sediment budgets to management of sandy wave-dominated shorelines, a case study of Twofold Bay, southeastern Australia

Coastal compartments provide a framework for considering sediment budgets by defining the boundaries between adjacent beaches or sections of coast with a common sediment source. Here we present Twofold Bay as an ideal field laboratory to test the coastal compartment management approach, and in particular, note the relevance of long-term coastal evolution to shorter term planning timescales. Twofold Bay on the New South Wales south coast, Australia, contains four main beaches (Aslings, Boydtown, Whale and Fisheries Beaches) and associated barrier systems. We present a range of existing geological and geomorphic information combined with new field data which demonstrate considerable variation in the Holocene evolution and sediment budget of these adjacent beaches. These data show three broad sediment types exist within Twofold Bay and its beach systems: Type 1 is a mature quartz-rich sand derived from the shelf. Type 2 is a fine carbonate-rich sand from local biogenic production, and Type 3 is a coarse-fine angular feldspathic sand sourced from the Towamba River which drains to Twofold Bay via the southern end of Whale Beach. Newly available high-resolution topography and bathymetry as well as sediment thickness maps, have enabled shoreface geometry and basement topography to be estimated seaward of each beach and reveal considerable variability between sites helping explain past shoreline behaviour. Several new optically stimulated luminescence (OSL) ages for Boydtown Beach, combined with existing ages, confirm two distinct phases of shoreline progradation, initially at 0.16 m/yr, and then over the past ∼1500 years, at 0.65 m/yr. The increase in progradation rate reflects sediment supply from the Towamba River via Whale Spit. While these two beaches have become interconnected, Aslings Beach and Fisheries Beach are dominated by sediment Type 1 and Type 2 respectively and have different evolutionary histories with Aslings Beach forming a stationary barrier while Fisheries has prograded at 0.15 m/yr over the past ∼4300 years according to a new set of OSL ages. The Holocene evolution of these four adjacent beaches has resulted from their differing sediment sources and budgets and is in accord with several available datasets of decadal shoreline changes. These results demonstrate that spatial variation in shoreline behaviour is driven by differences in sediment budget and that just as adjacent beaches have behaved differently in the past, so will they in the future. Understanding these drivers of shoreline change is imperative to effective coastal management and planning in the context of projected future sea-level rise and other anthropogenic pressures.

Origin and Provenance of Archean Keewaywin Formation clastic rocks at Sandy Lake, NW Ontario, Canada: Constraints on Archean weathering and depositional processes

Mesoarchean supracrustal sedimentary and volcanic rocks reflect provenance, depositional, tectonic and metamorphic conditions in Archean cratons. In the Sandy Lake Greenstone Belt within the North Caribou Terrane of the Superior Province, the Mesoarchean (∼2900 Ma) Keewaywin Formation is a metamorphosed siliciclastic deposit of mudstone, quartz-rich arenite, and volcaniclastic feldspathic litharenites and schists. Analysis of the petrography, mineralogy, and whole-rock and mineral geochemistry of sandstones and pelites indicate that precursor kaolinitic muds, dissolved iron, and quartz-rich sands were developed in soils by moderate to intense, long term weathering of felsic and mafic basement rocks in a tectonically stable environment. The detritus, half or more pelitic, was eroded from those soils and deposited as mud, some aluminous kaolinitic, some ferruginous, and as quartz-rich sands in a low relief setting. Volcaniclastic detritus from contemporaneous felsic volcanism was deposited with continually available kaolinitic mud and quartz- rich sediment. Kaolinitic aluminous muds were variously metasomatised at surface or near surface conditions with K, yielding muscovite-rich schists (as much as 95% muscovite); Ca and Na metasomatism yielded mm-scale, plagioclase rich laminae (up to 89% normative plagioclase) indicative of evaporite conditions. Ferruginous muds yielded chlorite rich schists (as much as 95 modal % chlorite). Reduced iron suggests the original sediments were deposited in an anoxic environment. New detrital zircon U/Pb age for a litharenite sample is 2930–2890 Ma is indicative of the age of an unconformity recognized in the North Caribou Core of the North Caribou Terrane. Detailed analysis of metamorphosed greenstone belt sedimentary rocks enables interpretation of their provenance, climate, weathering, depositional settings and post-depositional alteration. The shale compositions are particularly sensitive indicators of weathering conditions, hence climate. With age data, correlations between greenstone belts may allow recognition of regional large scale climate, weathering and sedimentation events.

Development of ECO-UHPC utilizing gold mine tailings as quartz sand alternative

To ensure ultra-high performance, in terms strength and durability, coarse aggregate is typically avoided in UHPC (ultra-high performance concrete). Instead, very fine quartz sand is usually used as the only aggregate. However, excessive extraction of sand from natural resources and its grinding and refining processes to prepare very fine quartz-rich sand are not economically or environmentally lucrative. Limited number of studies sought to address this concern, and very few of these studies investigated the use of mine tailings (quartz based tailings and iron ore tailings) in UHPC as sand alternatives. In the present study, the possibility of utilizing gold mine tailings, sourced from a gold mine in Western Australia (WA), as conventional quartz sand substitute in UHPC has been investigated. Results suggest that UHPCs, made with up to 80% replacement of quartz sand by the tailings, exhibit compressive strengths comparable to or higher than that of the UHPC with 100% quartz sand. 28-day strength greater than 120 MPa is achievable up to 100% replacement. The water absorptions and the initial rate of absorptions of UHPCs with tailings are generally lower than those of the UHPC without tailings. The leachability of toxic metals from UHPC with up to 100% tailings content lies well below the regulatory thresholds. The combined material and transportation cost of UHPC can be reduced by up to 33.1% replacing quartz sand by the tailings, for construction near the mine site. The CO 2 emission can be reduced by up to 12.1%. In the area near the mine site, utilization of the tailings can economically and environmentally, as well as in terms of durability, be a better option than quartz sand for construction works that require UHPC with 28-strength in excess of 120 MPa. • Mechanical, durability, and environmental performances of UHPC with gold tailings have been explored. • UHPC with up to 80% tailings shows compressive strength similar to or higher than UHPC with sand. • UHPC with tailings gives lower water absorption and initial rate of absorption than UHPC with sand. • Leachability of toxic metals from UHPC with any tailings content is substantially low. • Tailings use to produce UHPC near mine area helps reduce cost and environmental concerns.

Surface microstructures developed on polished quartz crystals embedded in wet quartz sand compacted under hydrothermal conditions

Intergranular pressure solution plays a key role as a deformation mechanism during diagenesis and in fault sealing and healing. Here, we present microstructural observations following experiments conducted on quartz aggregates under conditions known to favor pressure solution. We conducted two long term experiments in which a quartz crystal with polished faces of known crystallographic orientation was embedded in a matrix of randomly oriented quartz sand grains. For about two months an effective axial stress of 15 MPa was applied in one experiment, and an effective confining pressure of 28 MPa in the second. Loading occurred at 350 °C in the presence of a silica-saturated aqueous solution. In the first experiment, quartz sand grains in contact with polished quartz prism (overline10{1 }0) faces became ubiquitously truncated against these faces, without indenting or pitting them. By contrast, numerous sand-grain-shaped pits formed in polished pyramidal (17overline{6 }3) and (overline{4 }134) crystal faces in the second experiment. In addition, four-leaved and (in some cases) three-leafed clover-shaped zones of precipitation formed on these prism faces, in a consistent orientation and pattern around individual pits. The microstructures observed in both experiments were interpreted as evidence for the operation of intergranular pressure solution. The dependence of the observed indentation/truncation microstructures on crystal face orientation can be explained by crystallographic control of stress-induced quartz dissolution kinetics, in line with previously published experimental and petrographic data, or possibly by an effect of contact orientation on the stress-induced driving force for pressure solution. This should be investigated in future experiments, providing data and microstructures which enable further mechanism-based analysis of deformation by pressure solution and the effect of crystallographic control on its kinetics in quartz-rich sands and sandstones.

Sediment-routing controls on sandstone bulk petrographic composition and texture across an ancient shelf: Example from Cretaceous Western Interior Basin, Utah and Colorado, U.S.A.

ABSTRACTSediment-routing controls on sandstone texture and bulk petrography have been evaluated in linked alluvial–coastal–shelfal deposits of the Upper Cretaceous Castlegate Sandstone, Blackhawk Formation, Star Point Sandstone, and Mancos Shale (Western Interior Basin, Utah and Colorado, USA) using thin-section analysis of representative outcrop samples in the context of a high-resolution sequence stratigraphic and paleogeographic framework. The studied strata record deposition from two styles of sediment-routing system within an overfilled foredeep and contiguous intra-continental seaway. First, multiple transverse drainages supplied sand to fluvial, shoreline, and shelf segments of sediment-routing systems characterized by down-dip transport distances of 150–450 km and significant strike-oriented sediment transport along the shoreline. Second, the distal shoreline–shelf segment of an axially supplied sediment-routing system was characterized by sand transport for a distance of c. 300 km.Bulk petrographic composition indicates that transverse sediment-routing systems were sourced from catchments that supplied quartz-rich sand with a subordinate lithic component, while the large axial sediment-routing system was sourced from a catchment(s) supplying slightly more feldspathic sand. Thin-section measurements of mean grain size, sorting, skewness, and ratio of minimum-to-maximum diameter (a proxy for sphericity) are similar for sandstones deposited in fluvial, shoreline, and shelf segments of the transverse sediment-routing systems and in the shoreline–shelf segment of the axial sediment-routing systems, although hydrodynamic sorting is important in locally segregating grain-size populations within each segment. Further, textural analysis of detrital quartz, feldspar, and lithic sand-grain populations shows little evidence of relative change in mean grain size or apparent grain sphericity with downsystem distance, implying that sand-grain populations of different petrographic composition did not undergo significant differential mechanical breakdown during transport. Instead, the textural characteristics of these sand-grain populations are inferred to have been controlled mainly by bedrock lithology and recycling in source catchments. The textural signal of sediment-source areas then propagated downsystem in the sand fraction of detrital sediment supply. This inference is supported by the fine- to medium-grained, well- to very well-sorted character of all sandstone samples, consistent with recycling of sandstones and quartzites from the Sevier fold-and-thrust belt.

Holocene evolution of the wave-dominated embayed Moruya coastline, southeastern Australia: Sediment sources, transport rates and alongshore interconnectivity

Sediment budgets on wave-dominated coastlines are important in determining shoreline behaviour and are primarily inherited from geological-scale coastal evolutionary history. Sediment compartments provide a framework to conceptualise and investigate sediment budgets over a range of time and space scales. This study aims to assess the sediment budget for a secondary coastal compartment on the New South Wales (NSW) south coast ∼26 km in length and containing five adjacent but discrete Holocene coastal bay barriers: Barlings Beach, Broulee Beach, Bengello Beach, Moruya Heads Beach and Pedro Beach. Building on earlier morphostratigraphic studies, a new series of Optically Stimulated Luminescence (OSL) ages are presented for foredune ridge sequences at previously un-dated sites. Additional Ground Penetrating Radar (GPR) transects complement earlier stratigraphic datasets, and seamless topographic and bathymetric LiDAR datasets provide insight into subaerial coastal deposits and inner shelf morphology in this region. The results demonstrate that barriers within the compartment have two different sediment sources. The barriers are dominated by shoreface supply of quartz-rich sand transported onshore as shoreface morphology evolved towards equilibrium. Skeletal carbonate sand became an important component of the sediment budget for the northern Barlings and Broulee beaches after ∼3000 years ago. Shoreline progradation at Bengello Beach has been steady throughout the mid-to late- Holocene. Bengello contains the largest volume of Holocene sand and accreted at an average rate of 3.1 m3/m/yr (for the current shoreline length). The other barrier systems have experienced changes in sediment accumulation rate as their shorelines prograded seaward resulting in changes to their alongshore interconnectivity. Rapid filling of the Pedro Beach embayment by ∼4000 years ago initiated headland bypassing and northward sand transport to Moruya Heads Beach which only then commenced progradation. In contrast, as Broulee and Bengello Beaches prograded they converged in the lee of Broulee Island forming a tombolo which led to division of the former continuous shoreline into two. A marked increase in skeletal carbonate content at Broulee occurred after this separation attesting to the restriction of the southern quartz-sand source replaced by local carbonate production. This study emphasises the importance of understanding the long-term temporal variability in sediment budget and embayment interconnectivity in determining shoreline response to changing boundary conditions such as sea level and wave climate as well as contemporary anthropogenic influences.

Tsunami deposits and recurrence on a typhoon-prone coast of northern Taiwan from the last millennium

Widely known for its hazardous history, Taiwan holds valuable records of NW Pacific tsunamis and typhoons. Despite the similarity between tsunami and typhoon deposits, historical accounts enabled the identification of the 1867 tsunami deposit on the northern coast through matching with the record-setting inundation. However, the identification of prehistoric tsunami deposits has been hindered by severe sediment reworking and post-depositional changes produced by the typhoon-prone, tropical, and humid climate. In this study, we investigated the upper Holocene facies and their sediment sources and radiocarbon ages on distal floodplains and rocky backshores of the northern coast, where sediment reworking is less intense. Four decimetre-thick gravelly layers were identified, intercalated with fluvial mud and colluvium. The gravelly layers are composed of beach-derived quartz-rich sand and rounded gravels of the sedimentary basement rocks, longshore-drift andesite and stranded pumice. The remarkable layer thickness, gravel size, and quartz richness were determined to have endured post-depositional changes. The event layers are sharp-based, matrix-supported, and poorly sorted and have recorded scouring, sediment entrainment and rapid fallout of suspension-rich turbulent flows that probably originated with tsunamis. The event layers occur 0.5–0.8 km inland and 3–11.5 m above sea level, matching the 1867 tsunami inundation and wave height, respectively. Radiocarbon dating tied the event layers to the 1867 tsunami and three prehistoric events that occurred in the periods: 1545 to 1810, 1293 to 1414 and 1090 to 1235, representing a recurrence interval of 83–436 years over the last millennium.

Mixed siliciclastic-carbonate-evaporite sedimentation in an arid eolian landscape: The Khor Al Adaid tide-dominated coastal embayment, Qatar

The Khor Al Adaid embayment of southern Qatar represents a unique shallow-water mixed siliciclastic‑carbonate coastal depositional system that developed in a hyper-arid climatic setting over the past 6000 years. The embayment, which was formed during the Flandrian transgression as a result of flooding across a partially fault-controlled incised fluvial drainage, is supplied by quartz-rich sands delivered by wind-blown dunes migrating southward across the surface of Qatar. These offshore-migrating eolian-derived sediments are being redistributed by tidal currents in an otherwise low-energy coastal zone, where in situ formation of carbonate mud and a low-diversity skeletal assemblage is ongoing within salinity-restricted environments. Three depositional sectors are delineated: 1) an energetic, linear, fault-controlled Entrance Channel into which the eolian dunes spill directly; 2) a relatively deep (up to 20 m) Outer Lagoon, interpreted to represent a flooded karst-collapse structure; and 3) a sprawling, low-energy, shallow (<2 m) Inner Lagoon occupying low-lying areas between deflated eolian dunes.Physical oceanographic modeling, integrating multi-seasonal current meter and tidal gage measurements, demonstrates tidal current flow velocities are relatively high in both the Entrance Channel and at the constricted entrance to the Inner Lagoon. Associated flow expansion into less confined areas results in deposition of the eolian-derived sands as flood-tidal deltas, one in the Outer, and two in the Inner Lagoon. A weakly-developed ebb-tidal delta occurs where the Entrance Channel debouches into the Arabian Gulf. Flood-tide dominance is also apparent in Entrance Channel deposits, where sand accumulates in seaward-terminating “ebb barbs” along the margins of the flood-dominant thalweg. Such flood-tide dominance of the thalweg is unusual and likely reflects the absence of river discharge. Evidence of significant inverse estuarine circulation (seaward flow of a brine along the embayment floor) is mostly absent in spite of the landward increase of salinity, where concentrations reach more than double normal seawater salinity in the Inner Lagoon. Modeling results show that seaward-flowing brines formed in the Inner Lagoon are trapped in the relatively deep Outer Lagoon, and that mixing by tidal currents in the energetic Entrance Channel precludes the formation of vertical density gradients there. Because siliciclastic mud is essentially absent, and most of the sediment forming the deltas consists of sand, upper intertidal deltaic deposits that would normally consist of mud are absent, resulting in the flood-tide deltas having a pronounced lobate geometry similar to that of fluvial deltas formed predominantly of sand.Away from tidal deltas, low-energy lagoons are floored by carbonate mud of local production, with minor gypsum precipitating in the Inner Lagoon. Wind-generated waves only locally influence sedimentation, forming complex nearshore bars along some lagoonal shorelines. The overall landward increase in salinity is accompanied by a decrease in the diversity of benthic fauna and their skeletal remains. A fairly diverse faunal assemblage is observed in the Entrance Channel near the Arabian Gulf, including colonial corals, whereas the inner lagoon assemblage is dominated gastropods belonging to Pirenella cingulata. The remnants of large eolian dunes are preserved in the low-energy setting of the Inner Lagoon, segmenting the waterbody, and locally increasing restriction. The sedimentology of the arid-zone coastal Khor Al Adaid embayment may serve as an analogue for environmental settings that were perhaps more commonplace in arid zones of flooded continents during greenhouse times.

Shallow subsurface thermal structure onshore Denmark: temperature, thermal conductivity and heat flow

Available measured temperatures and thermal conductivities covering Danish onshore areas to a depth of about 300 m have been compiled and analysed. Temperature data from 236 borehole sites, including 56 boreholes with detailed temperature profiles, are applied together with thermal conductivities mea- sured on samples collected at 34 well-characterised outcrops and on core material from 20 boreholes. Significant thermal variations in the shallow subsurface are observed. At a depth of 50 m, a mean temperature of 8.9 ± 0.8°C is found, close to the mean annual surface temperature. Higher mean values of 9.7 ± 1.1°C found at 100 m and 11.6 ± 2.2°C at 200 m reflect a general increase of temperatures with depth. In contrast to the assumption commonly held, we observe significant lateral variations both lo- cally and regionally. At a depth of 100 m, temperatures vary between 7.3 and 13.0°C across Denmark, and at 250 m between 9.6 and 17.9°C. Mean values of the thermal conductivities lie within a range of 0.6–6 W/(m·K) measured water- saturated at laboratory conditions. The majority of values are within the interval of 1–3 W/(m·K) and show a strong correlation with lithology. The content of quartz and the rock porosity (the content of water) are found to be two main factors controlling the observed variations. Characteristic temperature gradients are in the range 1–4°C/100 m. Following Fourier’s law of heat conduction, a clear correlation is observed between temperature gradients and thermal conductivities of different lithologies. Intervals of quartz-rich sand deposits with high thermal conductivity show low temperature gradients, chalk and limestone intervals with intermediate conductivity display intermediate gradients, while sections with fine grained clay deposits of low thermal conductivity show high gradient values. A correlation analysis provides an estimate of regional shallow heat flow of 37 ± 5 mW/m2, consistent with local, classically determined heat-flow values from shallow borehole data. However, it is significantly below deep background heat flow, and this is believed to be caused by long-term paleoclimatic effects. The shallow subsurface thermal regime across the Danish area is largely controlled by thermal conduction. Only locally, and in rare cases, do we observe temperature perturbations due to ground- water migration. In addition to general geoscientific purposes, our results are important for several applications including exploitation of shallow geothermal energy and the use of the subsurface for heat storage and cooling purposes.

Application of ultrafine fraction soil extraction and analysis for mineral exploration

The need to innovate to advance exploration success is ongoing and, while regional geochemical surveys are common, increasing the data we collect and improving survey results has stagnated. A new adaption of existing methods known as UltraFine+™ extracts the &lt;2 µm fraction of soils and sediments, which is then analysed and combined with spectral mineralogy proxies and physicochemical properties to improve targeting for Au and base-metal exploration. We applied the UltraFine+™ workflow to three small orientation site studies in Western Australia, and reprocessed archived regional soil samples from the Geological Survey of Western Australia to test the method. The orientation programme ( c . 200 samples) involved samples from the Leonora and Sir Samuel 1:250 000 map sheets, an area that hosts known major Au and base-metal deposits. We then applied this approach to the Kingston 1:250 000 map sheet area, analysing a further 300 samples in a region on the Yilgarn Craton margins that is essentially greenfields, as there has been little exploration and the original geochemical survey data were heavily censored due to the abundance of transported regolith dominated by quartz-rich sand. The archived samples were specifically selected soils (sheetwash or sandplain) with a component of Quaternary–Tertiary transported cover. Results at the orientation test sites (Telfer West, Tooting Bec and DeGrussa) were promising. Importantly, the study revealed a marked decrease in censored results for Au (from 63% to 10% below detection limit). Geochemistry and some example indices for mineral exploration and lithology mapping, as well as example maps using the additional spectral mineralogy proxies or particle-size variation, are presented. The application of the &lt;2 µm particle-size separation and the UltraFine+™ workflow importantly demonstrate the additional value from (re-)assaying regional soil and sediment samples to generate new targets and improve regional geochemical maps. This is an exercise that can be applied to new greenfields surveys and, when exploration budgets are lean, to archived samples.

Provenance, shallow to deep diagenesis, and chemical mass balance in supermature arenites and pelites, Ordovician Simpson Group, Oklahoma and Kansas, U.S.A.

This study, considering original detrital compositions and diagenetic alterations, relates sandstone and shale mineral and chemical composition to provenance and mass balance between the sedimentary assemblage and its provenance. Mature quartz-rich sandstones and siltstones with clay-rich shales in cores at depths of 60 m–5.2 km and burial temperatures of <50 to >150 °C from over 50 wells were utilized in this work. These provide the material for analysis of compositions and alterations in coastal and shallow marine clastic sedimentary rocks of the Middle Ordovician Simpson Group in Oklahoma and Kansas, U.S.A. Mineral and geochemical data were obtained by optical petrography, X-ray diffraction, scanning electron microscopy, electron microprobe, and whole rock X-ray fluorescence and ICP/MS analyses. Results of the study show significant progressive diagenetic changes with increased burial depth and temperature. Mineralogically and chemically, less altered rocks are comparable to modern quartz-rich sands and kaolinitic muds in siliciclastic sediments developed during humid tropical weathering in crystalline basement shield provenance in Africa and South America. By analogy to modern tropical cases, muds composed of major kaolinite with minor smectite and illite at deposition, were diagenetically transformed to illite-rich rocks by possible microbial action, at surface to shallow (<200 m, <40 °C) burial with influx of K, Rb and Mg from seawater. In sandstones, early open system diagenesis with calcite cementation and quartz overgrowths occurred at <1 km depth and < 40 °C. Further closed system silica diagenesis and K-metasomatism, occurred with deeper burial (to 3+ km and 100 °C) in the Pennsylvanian and Permian and later, during and following uplift of the Arbuckle and Wichita Mountains, with establishment of a new fold and thrust belt structural and hydrologic regime. Pressure solution of quartz and the illite to muscovite transformation in shales in the depth range 3–8 km, yielded silica for later generation quartz cement (10- >20%) in sandstone buried >3 km. During deep burial, high temperature (>110 °C) calcite cement from deep basin sources was precipitated in sandstones. Geochemical mass balance estimates, physical, and chemical evidence suggest quartz cement was sourced from within clastic rocks of the Simpson Group with minor external contribution of SiO2. Na is in low abundance due to loss in solution during weathering in the provenance. Rare earth elements (REE) have typical abundances and distributions in shales with enrichment in light REE; littoral environment siltstones and matrix-rich sandstones display enrichment of heavy REE in phosphatic brachiopod shell fragments.

Optically stimulated luminescence dating of coastal sediments at Funing Bay, Southeastern China

Abstract The possible role of environmental change, especially sea level change, as a stimulus for the development of human residence and migration is poorly understood. We investigate this problem by showing a record of sea-level change and coastal transformation based on a sediment core (FN1 core) and a Neolithic site (Pingfengshan site) obtained from the Funing bay on the northeast coast of Fujian, China. The Funing bay coastal area represents a unique feature in China’s Neolithic cultures, comprising a silty beach dominated by quartz-rich sand and several important sites of Huangguashan cultural period. Samples from FN1 core and Pingfengshan site were taken for grain size ananlyses and for optically stimulated luminescence (OSL) dating. The blue-light stimulated OSL signals were measured by the single aliquot regenerative dose (SAR) protocol to determine the ages of of the samples. Samples from FN1 core yield OSL ages ranging from 49.9 ka to 0.8 ka, providing the systematic geochronological evidence for the sea level change of Funing bay. The comparison of sea level change and Neolithic cultural periods presents a good relationship in coastal area of Fujian, China since about 7 ka before present. In detail, the cultural types of Keqiutou culture and Huangguashan culture all belong to coastal mountainous culture, of which flourishing periods corresponds to the higher sea level periods of mid-late Holocene. Tanshishan culture belongs to estuarine coastal culture, and most sites of this period correspond to a lower sea level located at lower altitudes.

Ceramic production at Selinunte (Sicily) during the 4th and 3rd century BCE: New archaeometric data through the analysis of kiln wastes

A set of 37 overfired ceramic samples was collected from the dump of two kilns sited in the productive area FF1 in the acropolis of Selinunte (south western Sicily), being specifically active in the period 409–250 BCE. The ceramic samples were analysed by thin-section petrography and chemical analysis, with the aim to establish a valuable ‘reference group’ representative of the ceramic produced at Selinunte during the Punic phase.The petrographic and chemical analyses allowed to state that the ceramic manufactures from the kilns operating in the FF1 insula are characterized by rather homogeneous textural/compositional features. The daily-use common ware here produced is characterized by aplastic inclusions mainly falling in the size classes of coarse silt and medium sand, with relative abundance ranging between 15 and 25% area. The inclusions are composed of monocrystalline quartz and, subordinately, of calcareous bioclasts, polycrystalline quartz, K-feldspar, plagioclase, chert, sandstones and acid rock fragments. The relatively low total chemical variability of the ceramic sample set reflects the specific incidence of the above-mentioned mineralogical and textural features. The variable amount of quartz-rich sand used for tempering the local raw clays produces slight variations in the SiO2/CaO concentration ratio. Nonetheless, the chemical ‘reference group’ defined through this study seems to be consistent and characterized by satisfactory low standard deviations and it is fully congruent with the geo-lithological background of the area.This new chemical ‘reference group’ might be applied to studies that are aimed to define the trade networks in that time in south western Sicily. It could also represent a useful starting point for future systematic studies concerning various ceramics classes (i.e. tableware, cooking ware, transport amphorae, etc.), taking into account the consumption and insular/extra insular trade dynamics of the ceramic products of Punic Selinunte.

New insights from microfauna associations characterizing palaeoenvironments, sea level fluctuations and a tsunami event along Sfax Northern coast (Gulf of Gabes, Tunisia) during the Late Pleistocene-Holocene

Late Pleistocene to Holocene evolution of the Northern coast of Sfax (Gulf of Gabes, Tunisia) is deduced on the basis of the analyses of sediment cores and coastal outcrops. The environmental changes are established by means of microfauna and mollusk assemblages and biocenotic parameters complemented by geochemical, sedimentological and correspondence analysis (CA). An opened embayment, rich in warm Senegalese fauna, allowed the deposition of quartz-rich sands Late Pleistocene in age. During the Late Holocene, a major modification of the environmental characters is recognized. The dominance of marine ostracod and coastal foraminifera coupled with high values of species richness characterize a widely opened lagoon. This lagoon is subjected to the action of the alongshore drifts which are responsible for the build-up of sand spits and the genesis of the present sebkhas. Two transgressive events, overlying the marine Late Pleistocene quartz-rich sands, are dated at 2018–2419 and 1001–1804 a cal BP. The dominance of marine and coastal foraminifera, the recurrence of ostracods and the high values of biocenotic parameters testify these two events. Sudden changes, toward 0–502 a cal BP, in the structure of populations, geochemical element concentrations and sedimentological trend argue in favor of a tsunami event and the settlement of peculiar environment. The latter records (1) the reworking of Holocene microfauna and Tyrrhenian sands rich in mollusks eroded from the marine substrata; (2) the high concentration of poorly stratified and poorly sorted shells; (3) fining-upward and thinning landward sequences; (4) the dominance of articulated bivalves and sharpened shells; and (5) the locally extensive deposits up to 160 m inland rising in altitude of about 0.75 m. This extreme event can be correlated with the tsunami generated by the strong earthquake, 1908 AD in age, in Eastern Sicily or by one of the earthquakes recorded during the 18th Century around the Mediterranean basin such as Sfax earthquake of 1750 AD.

Provenance of coastal dune sands along Red Sea, Egypt

Texture, mineralogy, and major and trace element geochemistry of 26 coastal dune sand samples were studied to determine the provenance and tectonic environment of two dune fields close to the beaches of Safaga (SF) and Quseir (QS) at the Egyptian Red Sea coast. Onshore winds generate fine, moderate, moderately-well to well-sorted, coarse-skewed to near-symmetrical dune sands with mesokurtic distributions. Winds pick up and transport grains from nearby beach sands and alluvial deposits into a wide Red Sea coastal plain at the border of the beach. The mineralogical (Qt–Ft–Lt) and geochemical composition of the sands, indicate that SF and QS coastal dune sands are mature and influenced by quartz-rich sands. The average CIA values in SF and QS coastal dune sands are low relative to the range of the PAAS, suggesting an arid climate and a low intensity of chemical weathering. The SF and QS coastal dune sand samples are plotted in the recycled orogen and partly in craton interior fields suggesting recycled older sedimentary and partly metamorphic-plutonic sources. The high content of quartz with shell debris and carbonates in coastal dune sands support the recycled sedimentary beach and alluvial sand sources. The dominance of heavy minerals like amphiboles (hornblende) and biotite in the coastal dune sands also supports the effect of metamorphic-plutonic source rocks. The new tectonic discriminant-function diagrams suggest that the coastal dune sands were deposited in a passive margin of a synrift basin. The results provide a good evidence for the extension in the Red Sea rift system during Oligocene-post Pliocene, which is consistent with the general geology of Egypt.

Phosphate: a neglected argument in studies of ancient glass technology

The phosphate content of ancient alkali-glass has been tested as an indicator for biogenic ash, used in glass production. The living tissue of plants and vertebrates accumulates phosphate that remains in native ash as a main component (1 to over 10 wt%) forming together with biologically essential element oxides a complex chemical fingerprint that characterises any glass made with it. If, instead of native plant ash its alkali extract is used, soluble oxides are concentrated in the extract whilst insoluble oxides get depleted, leading to a different elemental fingerprint of the glass. Geogenic raw-materials for glass production like quartz-rich sand, evaporitic natron, or limestone are virtually phosphate free (below detection limit up to ≈0.15 wt%). Several collections of ancient glass stemming from different archaeological excavations, regions and times have been analysed by instrumental methods (WD-XFA, ED-XFA, thermal techniques), i.e. flat- and hollow K–Ca glass dated 1699/1714 N = 340, Na–Ca glass 13th/14th cy N = 94, Na–Ca glass 7th/9th cy N = 110, and alkali-Ca glass La Tene N = 395. Although the phosphate content of native alkali plant ash gets diluted with quartz sand by a factor of roughly two in glass production, it remains a main component of the product glass. Wood-ash glass contains 1–3 wt% phosphate, whilst glass manufactured from halophyte ash contains around 0.2–1 wt%. When processed wood-ash is used, the phosphate content in glass sinks below 1 wt%, the depletion factor amounting to roughly 8–15. Glass made from evaporitic soda displays phosphate contents below 0.2 wt% in the cases examined. The phosphate content of ancient alkali glass thus indicates whether virtually phosphate-free evaporitic soda has been used as a flux, or native ash of halophile plants. Ternary melting diagrams reveal at least three groups of alkali glass: Naturally coloured forest glass displays a broad distributional pattern with minimum melting temperatures ranging from 1200 to ≥1450 °C, colourless potash-extract glass from 900 to ≈1200 °C, and the typical, tight cluster of Roman sodium-calcium glass ranges from 800 to ≈900 °C. The wide-spread sodium-lime glass made with native halophytic ash, contains besides Na2O as the chemical main component always some K2O, and melting temperatures range from 800 to ≈1000 °C.

Effect of Ground Mineralogy on Energy Pile Performance in Dense Sand

Geothermal energy piles have emerged as a cost effective and efficient solution for heating and cooling buildings through renewable energy. Although significant research effort has been dedicated to investigating the performance of these systems, the effect of ground mineralogy has received little attention. This study examines the likely performance of energy piles in dense sand with varying mineralogy. A 3D thermal discrete element model is used to determine the dry thermal conductivity of quartz, feldspar and mica rich sand. This is then used in a 2D finite element analysis to estimate the dissipation/extraction capacity of the soil surrounding a typical energy pile. A 35% increase in quartz content is predicted to result in 51% improvement in the thermal performance of a pile.

Physico-chemical properties of quartz from industrial manufacturing and its cytotoxic effects on alveolar macrophages: The case of green sand mould casting for iron production

Industrial processing of materials containing quartz induces physico-chemical modifications that contribute to the variability of quartz hazard in different plants. Here, modifications affecting a quartz-rich sand during cast iron production, have been investigated. Composition, morphology, presence of radicals associated to quartz and reactivity in free radical generation were studied on a raw sand and on a dust recovered after mould dismantling. Additionally, cytotoxicity of the processed dust and ROS and NO generation were evaluated on MH-S macrophages. Particle morphology and size were marginally affected by casting processing, which caused only a slight increase of the amount of respirable fraction. The raw sand was able to catalyze OH and CO2− generation in cell-free test, even if in a lesser extent than the reference quartz (Min-U-Sil), and shows hAl radicals, conventionally found in any quartz-bearing raw materials. Enrichment in iron and extensive coverage with amorphous carbon were observed during processing. They likely contributed, respectively, to increasing the ability of processed dust to release CO2− and to suppressing OH generation respect to the raw sand. Carbon coverage and repeated thermal treatments during industrial processing also caused annealing of radiogenic hAl defects. Finally, no cellular responses were observed with the respirable fraction of the processed powder.