Provenance Indicators Research Articles

Source areas of the Eastern Ebro Valley loess (NE Iberian Peninsula): Heavy mineral composition as a provenance indicator

AbstractLoess deposits of the Eastern Ebro Valley (NE Iberian Peninsula) occupy an area of ~2000 km2 mostly on the east of the Ebro depression and locally in the Móra Basin. We studied 38 samples of loess and 47 samples of their possible source areas, in order to determine the location of the origin of the loess materials, based on their particle size distribution and composition of heavy minerals. Our results clearly differentiate two depositional loess basins disconnected by the reliefs of the Pre‐Coastal Range with different mineralogical signatures: the Ebro Basin and the Móra Basin. The most relevant variables to discern source areas were the percentage of heavy minerals, the concentrations of zircon, staurolite, rutile and inosilicates, and the presence of gypsum. In the Ebro Basin, the largest set of loess deposits is located around a depocenter in the Batea region and along several lateral areas, with materials that come from the central alluvial plain of the Middle Ebro River (25 to >100 km travel distance), in addition to deflated materials from Miocene interfluvial substrates. On the other hand, loess deposits of the Móra Basin come from more proximal source areas (<15 km), originating from the alluvial materials of the Lower Ebro River that contain the contributions of its tributaries, the Cinca and Segre rivers. Taking into account the homogeneity in the mineralogical composition of complex loess sequences, we deduced a general WNW–ESE wind direction, which would have remained constant over the last two cold periods (MIS‐2 and MIS‐6). Along this axis, the Pàndols–Cavalls Range, with a height difference of 200–350 m, acted as a wind barrier separating the loess of Ebro Basin from the loess of Móra Basin.

A “Local First” Approach to Glacigenic Sediment Provenance Demonstrated Using U-Pb Detrital Zircon Geochronology of the Permo-Carboniferous Wynyard Formation, Tasmanian Basin

We propose that a “local first” approach should be applied to the interpretation of provenance indicators in glacigenic sediments of all depositional ages, especially where the glacier flow path is poorly constrained and the records of potential source lithologies are incomplete. Provenance proxies, specifically U-Pb detrital zircon geochronology, of glacigenic sediments are commonly used to infer the size and distribution of past ice centers, which are in turn used to inform ancient climate reconstructions. Interpretations of these proxies often assume that similar provenance signals between glacigenic units of the same depositional age are evidence that they were deposited by the same glacier, even when those units are, not infrequently, separated by thousands of kilometers. Though glaciers are capable of transporting sediment great distances, this assumption is problematic as it does not acknowledge observations from the geologic records of Pleistocene ice sheets that show provenance proxies in glacial sediments are most likely to reflect proximal (within 100 km) sediment sources located along a specific flow path. In a “local first” approach, provenance indicators are first compared to local source lithologies. If the indicator cannot be attributed to proximal sources, only then should progressively more distal sources be investigated. Applying a local first approach to sediment provenance in ancient glacial systems may result in significant revisions to paleo ice sheet reconstructions. The effectiveness of the local first approach is demonstrated here by comparing new U-Pb detrital zircon dates from the Permo-Carboniferous glacigenic Wynyard Fm with progressively distal source lithologies along the glacier’s inferred flow path. The Wynyard Fm and source lithologies were compared using an inverse Monte-Carlo unmixing model (DZMix). All measured Wynyard Fm detrital zircon dates can be attributed to zircon sources within 33 km of the sample location along the glacier’s flow path. This interpretation of a proximal detrital zircon provenance does not conflict with the popular interpretation made from sedimentological observations that the Wynyard Fm was deposited by a large, temperate outlet glacier or ice stream that flowed south-to-north across western Tasmania. Overall, a local first approach to glacial sediment provenance, though more challenging than direct comparisons between glacigenic sedimentary deposits, has the potential to elucidate the complex histories and flow paths of glacial sedimentary systems of all depositional ages.

Maturity Matters in Provenance Analysis: Mineralogical Differences Explained by Sediment Transport from Fennoscandian and Variscan Sources

The significance of mineralogical maturity as a provenance indicator has long been debated and we use this study to demonstrate that it can indeed be a powerful tool to track the distribution of sandstone reservoirs. We investigate the cause of the pronounced geographic and stratigraphic differences in mineralogical composition that are found in the Upper Triassic–Lower Jurassic Gassum Formation across the Norwegian–Danish Basin and surrounding areas. Zircon U-Pb dating of 46 sandstone samples including analysis of 4816 detrital grains are combined with quantifications of the detrital mineralogical composition and placed in a sequence stratigraphic framework. The results show that the Gassum Formation can be divided into a southeastern region with high mineralogical maturity and a less mature region to the northwest with more feldspars, rock fragments, micas, and heavy minerals. Both the mineralogical assemblage and the provenance signature have been thoroughly homogenized in the SE region where sediment supplies from the Fennoscandian Shield and the Variscan Orogen are evident. In the NW region, sediment was initially supplied from Fennoscandia only, but the provenance abruptly changed from the Telemarkia Terrane to comprising also the more distant Caledonian Orogen resulting in a different mineralogical assemblage. The change occurred during a basinwide regression and may be caused by tectonic movements in the hinterland that permanently changed the composition of the sediment supplied to the basin.

Luminescence Sensitivity of Quartz From Rocks Under in situ Chemical Weathering Conditions

In provenance investigation of Quaternary sediments, quartz luminescence sensitivity (QLS) has been employed as a technique. The weathering and influence on the earliest signs of luminescence sensitivity of sedimentary quartz require more consideration. In this study, the QLS properties of eight samples of Permian biotite monzogranite from a borehole in the southern tropics of China are investigated. The degree of chemical weathering does not correspond with the QLS values of samples that have undergone varying degrees ofin situweathering. We hypothesize that the variation of the irradiation field during thein situchemical weathering process may affect the QLS, but not considerably within 200 ka. In addition, we discovered that quartz from the same source undergoes varying degrees ofin situchemical weathering, but has a constant response to irradiation-bleaching cycles (IBCs). The presence of variances in the thermal activation curves (TACs) of the same rock body indicates that further research is required to apply TAC as a provenance indicator.

On the provenance of GEMS, a quarter century post discovery

The provenance of GEMS (glass with embedded metal and sulfides) in cometary type interplanetary dust particles is investigated using analytical scanning transmission electron microscopy and secondary ion mass spectrometry. We review the current state of knowledge and closely examine the densities, elemental compositions and distributions, iron oxidation states, and isotopic compositions of a subset of GEMS in chondritic porous interplanetary dust. We find that GEMS are underdense with estimated densities that are 35–65% of compositionally equivalent crystalline aggregates. GEMS low densities result in a lower contribution to the bulk compositions of IDPs than has been assumed based on their volume fraction. We also find that element/Si ratios, assumed to be primary (indigenous), are instead perturbed by contamination and secondary alteration, including pulse heating during atmospheric entry. Fe in pyrrhotite inclusions was oxidized and Mg, S, Ca, and Fe were depleted relative to lithophile Al and Si, resulting in reduction in element/Si ratios. Because they trap outgassing elements, Fe-rich oxide rims that formed on the surface of GEMS are serendipitous “witness plates” to the changes in composition that accompany atmospheric entry. As a result of alteration, GEMS elemental compositions cannot reliably inform about their provenance. Except for highly anomalous oxygen isotope ratios measured in some large GEMS grains that indicate a contribution from circumstellar dust, oxygen isotope compositions are generally poor indicators of provenance. Prior work indicates that most GEMS fall close to the terrestrial oxygen isotope composition, which, however, does not exclude a presolar interstellar origin. Nitrogen isotopic compositions are more diagnostic. Elevated 15N/14N ratios indicate that GEMS accreted in conjunction with formation of organic matter by ion–molecule reactions in a cold (<50 K) presolar environment like the extreme outer nebula or interstellar medium. Considering all observations, we conclude that GEMS are most likely processed interstellar silicates.

The Books of King Sigismund at Uppsala University Library

ABSTRACT When Uppsala University Library was formally founded in 1620 and 1621, the book depot of the Crown, previously located on Gråmunkeholmen (today’s Riddarholmen) in Stockholm, was donated there. This collection inter alia contained the confiscated library of a Swedish nobleman and remnants from medieval Swedish monastery libraries. As Otto Walde conclusively proved in 1915, it also contained the Swedish parts of the library of the Swedish King Sigismund (Sigismund III in Poland), who was dethroned in Sweden in 1599. Sigismund’s books were soon scattered and spread among the rest of the book collections of Uppsala University Library, which were arranged according to subject, without any indication of provenance. The aim of the present article is to report what we currently know about Sigismund’s collection. Step by step, not least by the research of Otto Walde, but also by the ongoing work at the library, we are now able to know more titles and much more about the contents and destinies of this Royal book collection than what was previously known.

Variation in Luminescence Characteristics and Paramagnetic Defect Centres in Fine-Grained Quartz From a Loess-Palaeosol Sequence in Tajikistan: Implications for Provenance Studies in Aeolian Environments

Trapped charge characteristics in quartz are of increasing interest for their utility as indicators of sediment provenance. These include sensitivity of optically stimulated luminescence (OSL) and thermoluminescence (TL) signal and paramagnetic E1’ defect centre in quartz. Up until now, these methods have largely been used independently in provenance investigations, especially in aeolian systems. Variations in quartz OSL and TL signal sensitivity in loess-palaeosol sequences has been linked to shifts in sediment source corresponding to climatic fluctuations. However, the processes responsible for observed variation in OSL and TL sensitivity in quartz, including its link to the original rock source and/or its sedimentary history, remains a topic of contention. On the other hand, the intensity of E1’ defect centre in quartz is known to reflect the provenance of quartz, and is also routinely utilised as a provenance indicator in aeolian studies. In this study we aim to understand the variations in E1’ intensity and OSL (and TL) sensitivity by direct comparison of these characteristics in fine-grained quartz from a c. 60 m-thick loess-palaeosol sequence in Tajikistan. In doing so, we investigate the natural processes that may have led to variability in trapped-charge characteristics over the c. 500 ky timespan covered by the sequence. Our results suggest that apart from the inherent link to its provenance signature, the observed luminescence sensitivity of quartz especially in loess-palaeosol sequences are largely influenced by depositional and post-depositional processes during soil formation.

Luminescence characteristics of Scandinavian quartz, their connection to bedrock provenance and influence on dating results

The success of optically stimulated luminescence (OSL) dating relies to a large extent on suitable characteristics of the analysed mineral, in this case quartz. Previous OSL dating of Quaternary sediments in Scandinavia has shown that quartz characteristics vary widely across the region, resulting in dating studies with varied success. The aim of this study is to provide an overview of quartz luminescence characteristics in Sweden and Norway, evaluate their effect on dating results and discuss the underlying causes of their variability. A qualitative assessment of luminescence signal characteristics of quartz from Late Quaternary sediment deposits, from a range of geological and geographical settings, has been made by re-analysing data from samples previously dated at the Lund Luminescence Laboratory, Sweden. This allowed a general characterisation of signals and a study of the relationship of these properties to dating result ‘quality’. To quantify the results, selected samples were further analysed with single-grain measurements and with small aliquots. The results show that the average luminescence signal from quartz is fairly dim but dominated by a fast signal component and changes little during measurement. Dose determination precision is ∼4% for 8-mm aliquots and ∼6% for 2-mm aliquots. However, the luminescence signal characteristics have a spatial variation across Sweden and Norway, which appears to correlate with large-scale bedrock units. In areas of sedimentary bedrock outside the Scandinavian mountains and within the Blekinge-Bornholm province, the quartz is brighter and has a stronger fast signal component, while in the Caledonian orogenic belt, the signal is very weak and lacks a fast component. These differences lead to a range in precision of doses, from ∼2% to >40% (for doses in the order of 5–400 Gy), and in the number of rejected aliquots (0–100%) depending on location, but also implies that quartz luminescence can be used as a provenance indicator in part of Sweden and Norway. • OSL signals of most quartz from Sweden and Norway are dim but have a fast component. • Brighter quartz occurs e.g. in sedimentary bedrock areas. • Quartz from the Caledonian belt has low OSL signals dominated by slow components. • Bright quartz yields precise (2%) dose estimates, dim quartz less precise (19%). • Spatially contrasting OSL characteristics show promise for provenance studies.

Geochemistry and granulometry as indicators of paleoclimate, weathering, and provenance of sediments for the past 1,00,000 years in the eastern Arabian Sea

• Climate during MIS1, 3, 5a & 5c was hot and humid with intense SWM than YD, LGM, MIS2, 4, 5b. • Source area has experienced moderate to intense chemical weathering. • Provenance of sediments was felsic rocks during warm periods and mafic rocks and dust during cold periods. • Sources of sediments are ∼50% basalt , 40–80% gneiss and 10–20% dust. • Climate of lower and higher latitudes suggests inter-regional teleconnections . Geochemical and granulometric investigation of a 408 cm long sediment core raised from the Eastern Arabian Sea was carried out to decipher the climate, weathering, dust flux and provenance of sediments during the past 100 ka. The diagnostic ratio of Cr/Ni (0.99 to 1.77), Rb/Al (6.01 to 17.14), Ti/Al (0.02 to 0.03), Fe/Al (0.94 to 1.61), Mg/Al (0.31 to 0.59) and silt% (38.68 to 66.37) indicate hot and humid climate with the intensification of south-west monsoon during marine isotope stage (MIS) 1, 3, 5a and 5c and cold and dry climate with the intensification of the northeast monsoon and high dust flux during Younger Dryas cooling, last glacial maximum, MIS 2, 4 and 5b. The clay% (20.42 to 53.92), Silica–Titanium Index (71.88 to 86.28), Ruxton Ratio (2.89 to 7.22), and Th/U ratio (0.98 to 4.11) indicate moderate to intense chemical weathering in the source area during warmer climate. Th(ppm) versus Sc(ppm), La/Th versus Th/Yb, Al 2 O 3 % versus Fe 2 O 3 %, Th/Sc versus Sc(ppm), La/Sc versus Sc/Th ratios and La-Th-Sc plot indicate intermediate/mixed sources for sediment provenance. Sand% (2.82 to 25.3), Si/Al (2.74 to 7.43), ΣLREE/ΣHREE (7.65 to 10.40), La/Sc (2.24 to 3.55) indicate felsic sources from Peninsular India during warm climates and ΣREE (103.98–201.17), Rb/Ga (1.36–4.33), Ni (70.42–137.3 ppm), Rb (55.39–138.90 ppm) indicate mafic sources from Deccan Traps and Arabian desert during cold climates. The synchronous relationship between the climate of lower and higher latitudes was observed, suggesting the global teleconnections of climate during the Late Quaternary.

Fatty acid profiles as natural tracers of provenance and lipid quality indicators in illegally sourced fish and bivalves

Determining where harvested or produced seafood comes from is a pressing issue worldwide, with growing consumers’ demand for traceable and sustainable seafood products. Identifying fine-scale traceability markers is particularly important in the context of small-scale fisheries, which are prone to illegal harvesting and mislabelling and associated food safety risks. Here we explored the power of fatty acid profiling as a fine-scale tracer of the geographical origin (<30 km apart) of the Peppery furrow shell bivalve (Scrobicularia plana) and the European seabass (Dicentrarchus labrax) collected in three locations within a large, urbanized estuary. Fatty acid profiling provided a high classification accuracy of both species to their collection sites (80%–100% for the seabass and the bivalve respectively). Fatty acid profiling also allowed the determination of food lipid quality indices. The EPA + DHA values and the atherogenic (Ai), thrombogenic (Ti) and the hypocholesterolemic/hypercholesterolemic (h/H) indexes were all within ranges of high lipid-quality seafood, albeit they varied significantly among collection sites (except h/H). Overall, results highlight the strength of fatty acid profiling as a natural marker to trace the geographic origin of small-scale fisheries products, which may be integrated into a broader regulatory monitoring framework.

242 The Importance of Frailty Assessment as a Mortality Indicator and Surgical Decision-Making Tool

Abstract Background Frailty is a multidimensional syndrome, which can lead to poorer health outcome. Frailty score is a proven reliable indicator of post-operative morbidity and mortality; however, its application in clinical practice is limited. Aim The study aimed to assess the association between frailty marker and one- year mortality rate and explore its impact in clinical decision making in patients with abdominal aortic aneurysms. Method Consecutive patients with abdominal, thoracic, and thoracoabdominal aortic aneurysms presented at dedicated aortic clinic between July 2019 and April 2020 were included. Markers for frailty and sarcopenia using Rockwood Clinical Frailty Scale, SARC-F questionnaire, morphometric analysis for sarcopenia, one-year mortality and fitness were recorded. Multi-disciplinary team (MDT) was blinded to frailty and sarcopenia data; surgical decisions made by MDT were recorded separately. Results We assessed 83 patients (median age 75 [72,82], 85% male; median aneurysm diameter 6cm [5.8,7.0]. Sixteen patients were deemed frail, five patients had sarcopenia and thirty-one patients had myopenia. Seventeen patients were deemed not fit for surgery; 41% of these were frail compared with 14% out of those who were deemed fit. The odds ratio of being frail and unfit for surgery was 4.33 (95% CI 1.27–14.82, p = 0.010). Frailty was significantly associated with one-year mortality irrespective of fitness for surgery, sarcopenia and myopenia (OR 10.28, 95%CI 1.82–57.93, p = 0.009). SARC-F and myopenia was not associated with one-year mortality at (OR 1.66, 95%CI 0.03–19.25, p = 0.523) and (OR 0.59, 95%CI 0.09–2.85, p = 0.514), respectively. Conclusions Frailty score was associated with both one-year mortality and fitness for surgery decision made by MDT.

Sr-Nd Isotopic Composition of Pyroxenes as a Provenance Indicator of a Double-Volcanic Source in Sands of the Ofanto River (Southern Italy)

The sands of the Ofanto River (Southern Italy) include a volcaniclastic component represented by clinopyroxene, melanite garnet, amphibole and subordinate volcanic lithics. In order to infer the provenance of this component, we have conducted a microanalytical and isotopic study on the volcanic minerals of the sands collected in three different sites along the Ofanto River: (1) upstream sector, where only sedimentary rocks are drained; (2) middle course, along a tributary draining only the Monte Vulture volcanic rocks, (3) the mouth of the Ofanto. Moreover, minerals of the beach sands of the Tyrrhenian Cilento coast were analyzed for comparison. The microanalytical study and the Sr-Nd isotopic composition reveal the existence of two populations of pyroxenes characterized by distinct isotopic signatures and indicating a provenance from two different volcanic sources. One is confidently identifiable with Monte Vulture, and is evident in the minerals of the middle course and mouth sands. The pyroxenes of the upstream sector, isotopically similar to those of the Cilento coast, have a Campanian signature. The simultaneous occurrence of amphibole and garnet point to the explosive eruptions of Mount Vesuvius as the most probable sources of these minerals. The absence of Campanian pyroxenes at the mouth of the Ofanto River could be related to the occurrence of dams limiting the transport of solids along the river.

Petrography and geochemistry of sandstones from the Injana Formation, Hemrin South Mountain, Northern Iraq: Implications for provenance, weathering and tectonic setting

The sandstones of Upper Miocene Injana Formation were studied petrographically and geochemically in the Hemrin South Mountain area, northern Iraq. The sandstones vary between arkose and lithic arkose in composition (Q50F24L26) and are compositionally and texturally immature; meanwhile, the Log(Fe2O3/K2O)–Log(SiO2/Al2O3) diagram shows that they are divided between arkose, litharenite and wacke. These sandstones contain a wide spectrum of heavy minerals ranging from the most resistant ultrastable minerals (zircon, rutile and tourmaline), to the least resistant non‐stable minerals (amphiboles and pyroxenes). The provenance indicator diagrams QmFLt and QtFL indicate multi‐sources for these sandstones ranging from transitional craton, arc and recycled sediments. The major element provenance discriminant function plot shows that they are derived mostly from intermediate igneous provenance. All these suggest that the probable source of these sandstones is the igneous‐metamorphic rocks including the ophiolites of the Suture Zone, the imbricate zone, the Shalair‐Sanandaj‐Sirjan Terrane and the complimentary rock units in Turkey and Iran. The presence of glaucophane as the provenance indicator mineral for subduction zones is a further proof of the ophiolites having acted as the source rocks. Geochemically, the sandstones are enriched in Ca, V, Cr, Ni, Cu, Mo, Sn and Sb and depleted in all othe major, trace and rare earth elements (REE) relative to upper continental crust (UCC). The chondrite‐normalized REE pattern shows a distinct negative slope for the LREEs and a slight negative slope for the HREEs with an enrichment of LREE/HREE of 8.11–10.90 and a negative Eu anomaly of 0.70–0.83. The most probable source of REEs is the heavy minerals detected in the sandstones. Tectonically, the studied rocks were derived from collision rifting arc–related settings. The Chemical Index of Alteration (CIA), Plagioclase Index of Alteration (PIA) and Index of Composition Variation (ICV) values of the Injana sandstones suggest that they are compositionally immature and suffered from very weak weathering indicating the proximity of their source rocks and their deposition under dry continental conditions.

Magnetic susceptibility and grain size distribution as prospective tools for selective exploration and provenance study of iron sand deposits: A case study from Aceh, Indonesia

Almost all of the iron sand found in Indonesia, from Sumatra to Papua, is sandy deposit. Despite its variety of minerals, iron sand is commonly mined for low economic uses such as building material. As iron sands from different localities might have different characteristics (grain-size distribution, mineralogy, magnetic properties), such characteristics might in turn be used for provenance study or for selective mining. This study aims to examine iron sand deposits from two geographically close but geologically different regions, Lampanah and Anoi Itam, and to test the grain size distributions and their relationship with magnetic susceptibility as well as Fe content. In both Lampanah and Anoi Itam, the sizes of iron sands were predominantly medium sand (MS) and fine sand (FS), but they differed in mass percentage (M%). Generally, magnetic susceptibility increases as grain size decreases. Fe content is also grain size dependent, with higher Fe content in finer sizes. The results imply that the combination of grain size distribution and magnetic mineral composition might be used not only as a provenance indicator for iron sand deposits, but also as a criterion for selective mining.

Geochemical and petrographic characteristics of sediments along the transboundary (Kenya–Tanzania) Umba River as indicators of provenance and weathering

Abstract The Umba River basin is one of the smaller-scale hydrological basins in the East African region. It traverses two countries, with its catchment in the Usambara mountains in Tanzania, while it drains its waters to the Indian Ocean in Vanga, Kenya. The chemical and mineralogical compositions of the riverbank and bottom sediments of the Umba River were analyzed and evaluated to describe their source characteristics and provenance. The dominant minerals include quartz, K-feldspars, plagioclase, hornblende, pyroxenes, muscovite, biotite, and likely presence of clays such as kaolinite. The chemical index of alteration of the sediments indicate a moderate to high degree of alteration. They reflect a dominant mafic to intermediate igneous provenance consistent with the geology of the Umba River catchment that is characterized by the outcrops of the granitic Precambrian basement and the quartz-dominated Paleozoic Karoo Supergroup, overlain by Mesozoic and Cenozoic sediments dominated by both mafic and felsic minerals. The similarity of the chemical and mineralogical compositions of the Umba River sediments from source to mouth further indicates a uniform source in the upper course of the river and only subordinate contributions from the lower course where it passes the Karoo and the younger sediments.

Population validation of reproductive gene mutation loci and association with the litter size in Nubian goat

Litter size is an important component trait of doe reproduction. By improving it, production efficiency and economic benefits can be significantly provided. Genetic marker-assisted selection (MAS) based on proven molecular indicators could enhance the efficacy of goat selection, as well as litter size trait. Many molecular markers have been identified that they can be used to improve litter size in different goat breeds. However, the presence and value of these markers vary among goat breeds. In the present study, we used the reported loci on other breeds of goat as candidate loci to detect whether these loci appear in this Nubian goat population; then we proceed to genotype and detect surrounding loci (50 bp) by multiplex PCR and sequencing technology. As a result, 69 mutations (59 SNPs and 10 indels) were screened out from 23 candidate genes in Nubian goat population, 12 loci were significantly associated with the litter size of first-parity individuals; 5 loci were significantly associated with the litter size of second-parity individuals; 3 loci were significantly associated with the litter size of third-parity individuals. In addition, five loci were significantly associated with the average litter size. The additive effect value of KITLG: g.18047318 GA in first parity, KITLG: g.18152042GA in third parity, KISS-1: g.1341674 CG in first parity, and GHR: g.32134187GA in second parity exceed more than 0.40, and the preponderant alleles are G, C, A and G, respectively. Further, linkage disequilibrium analysis of 21 mutation loci shows that 3 haplotype blocks are formed, and the litter size of combination type AACC in KISS-1 gene and AAGG in KITLG gene are significantly lower than that of other combinations genotype in first parity (). These findings can provide effective candidate DNA markers for selecting superior individuals in Nubian goat breeding.

A sedimentary record from the Makarov Basin, Arctic Ocean, reveals changing middle to Late Pleistocene glaciation patterns

Sediment core ARC5-ICE6 from the Makarov Basin was used to reconstruct circum-Arctic glaciation and surface-ocean circulation history for the Middle to Late Pleistocene, ∼0.5–0.7 Ma. Sedimentary proxies include elemental composition, coarse grain content, clay mineralogy, and radiogenic isotopes (Sr-Nd-Pb). Earlier studied records from the central Arctic Ocean were compared with ICE6 for a broader paleoceanographic context. Results indicate predominant sediment delivery from the Eurasian shelves and glaciated mainland with intermittent glacial inputs from North America. Low proxy variability prior to Marine Isotope Stage (MIS) 6 (∼0.2 Ma) suggests persistent sediment transport by sea ice via the Transpolar Drift and limited glaciation at the Eurasian margin. Since MIS 6, sediment inputs and provenance exhibit large shifts between glacial- and interglacial-type environments. The overall northern Eurasian Ice Sheet (EAIS) expansion was possibly related to climatic cooling and growth of a perennial sea ice in the Arctic Ocean. Provenance indicators from MIS 6, 5b and 4/3 reflect EAIS expansions followed by deglacial meltwater discharge from west Siberia. This provenance indicates a strong cyclonic circulation in the Arctic Ocean characterized by a significantly eastward-extended Transpolar Drift. Different glaciogenic sourcing and attendant circulation are proposed for several events within MIS 5 and 3, where proxies indicate increased sediment inputs from North America rather than Eurasian ice sheets. Overall limited glacial influence inferred for MIS 3 is consistent with relatively high sea level reconstructed for this interstadial. The Last Glacial Maximum is barely identifiable in the ICE6 record due to low glacial inputs and/or depositional hiatus.

Quantitative geochemistry as a provenance indicator for surface sediments in the north Jiangsu radial sand ridges (NJRSR) in the South Yellow Sea, East China

The North Jiangsu radial sand ridges (NJRSR) are typical sedimentary bodies distributed along the continental margin of China. Historically, the Yellow and Changjiang Rivers transported terrigenous sediments into the sea, depositing them in the study area. However, the provenance of the sediments in the NJRSR is not conclusively understood. In this study, the grain sizes and major elemental geochemistry of 33 surface sediment samples were investigated to discern the provenance of the sediments in the NJRSR. The results indicate that the sedimentary components are primarily silt (53.60%), sand (35.60%), and clay (10.80%). The grain size (Mz) of the NJRSR coastal surface sediments was 2.5–8.5 Φ, with an average of 5.1 Φ, and had high SiO2 and Al2O3 contents (on average, SiO2 and Al2O3 accounted for >68%). The statistical results of the geochemical analyses were reflected in the control on sediment elemental components by riverine transport in the study area, which were then used to divide the study area into three sedimentary provinces. Elemental ratios (Mg/Al, Fe/Al, K/Al) were used to discern the provenance of the NJRSR surface sediments, indicating that the inputs from the Yellow and Yangtze rivers are the dominant sediment sources in the study area. Using the inverse model, a quantitative estimation revealed that average sediment contributions of the Abandoned Yellow and Yangtze rivers were 67.4% and 32.6%, respectively. In addition, modern current systems play an important role in controlling sediment transport from the Abandoned Yellow and Yangtze rivers to the NJRSR. This study demonstrates the importance of geochemistry for quantitatively determining the provenance of the NJRSR, which is especially useful for quantitatively investigating Earth surface processes in global shelf-marginal seas.

What's Hot in Breast MRI.

Several articles in the literature have demonstrated a promising role for breast MRI techniques that are more economic in total exam time than others when used as supplement to mammography for detection and diagnosis of breast cancer. There are many technical factors that must be considered in the shortened breast MRI protocols to cut down time of standard ones, including using optimal fat suppression, gadolinium-chelates intravascular contrast administrations for dynamic imaging with post processing subtractions and maximum intensity projections (MIP) high spatial and temporal resolution among others. Multiparametric breast MRI that includes both gadolinium-dependent, i.e., dynamic contrast-enhanced (DCE-MRI) and gadolinium-free techniques, i.e., diffusion-weighted/diffusion-tensor magnetic resonance imaging (DWI/DTI) are shown by several investigators that can provide extremely high sensitivity and specificity for detection of breast cancer. This article provides an overview of the proven indications for breast MRI including breast cancer screening for higher than average risk, determining chemotherapy induced tumor response, detecting residual tumor after incomplete surgical excision, detecting occult cancer in patients presenting with axillary node metastasis, detecting residual tumor after incomplete breast cancer surgical excision, detecting cancer when results of conventional imaging are equivocal, as well patients suspicious of having breast implant rupture. Despite having the highest sensitivity for breast cancer detection, there are pitfalls, however, secondary to false positive and false negative contrast enhancement and contrast-free MRI techniques. Awareness of the strengths and limitations of different approaches to obtain state of the art MR images of the breast will facilitate the work-up of patients with suspicious breast lesions.

U\u2013Pb ages of detrital zircons in Cretaceous\u2013Paleogene/Neogene kaolins within Eastern Dahomey and Niger Delta Basins (Nigeria) as provenance indicators

Detrital zircon grains within four (4) deposits including two (2) Cretaceous and two (2) Paleogene/Neogene kaolins in Nigeria were analysed using U–Pb LA-SFICP-MS to determine their provenance. The zircon textures were dominated by xenocrystic cores and oscillatory zoning in the Cretaceous and Paleogene/Neogene kaolins, respectively. The Th/U ratios obtained for the detrital zircon grains within the kaolins were predominantly within known values for rocks with magmatic origin. The age populations obtained for the detrital zircon grains were dominated by values from 529 to 978 Ma within the Neoproterozoic, followed by values from 1754 to 2497 Ma of the Paleoproterozoic. Detrital zircon ages obtained between 553.2 ± 6.2 and 583.5 ± 2.0 Ma represent part of the minimum provenance ages for the primary minerals that were kaolinised. The Cretaceous–Paleogene/Neogene kaolins were derived from parent rocks of Eburnean and Pan African ages within the Western and Northern Nigeria Basements.