Scientific Drilling最新文献

{"title":"Simple evaluation of the fold axis, axial plane, and interlimb angle from a borehole image log","authors":"Y. Hamada, Y. Sanada, T. Hirose","doi":"10.5194/sd-31-85-2022","DOIUrl":"https://doi.org/10.5194/sd-31-85-2022","url":null,"abstract":"Abstract. Folds and fractures are important structures that preserve information on the past stress evolution; however, folds remain largely unexplored. Studying folds remains challenging, as no simple and unified method can be used to evaluate fold parameters, which include the fold axis, axial plane, and interlimb angle with depth. In this study, we propose a method to calculate the fold parameters of cylindrical concentric\u0000folds by considering the point at which the bedding trend changes as an\u0000inflexion point of the fold. The inflexion point is identified from the\u0000analysis of bedding orientation, which can be obtained by borehole image\u0000log. The orientation of the fold axis and the axial plane were geometrically calculated based on the inflexion surfaces at both ends of the folds. The application of this method is illustrated using a simulated fold model. It is shown that these fold parameters are calculated using the depth of the fold and are reliable to a certain extent, despite the uncertainty of the inflexion points. Although the extraction method assumes cylindrical concentric folds, it can be applied to symmetric folds to estimate the orientation of the fold axis and axial planes. The method developed in this study is expected to have a wide range of applications in structural geology as it can estimate the fold parameters of each fold traversed by a borehole.\u0000","PeriodicalId":51840,"journal":{"name":"Scientific Drilling","volume":"39 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72907756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A channel sampling strategy for measurement of mineral modal and chemical composition of drill cores: application to lower oceanic crustal rocks from IODP Expedition 345 to the Hess Deep rift","authors":"R. Wintsch, R. Meyer, D. Bish, R. Deasy, T. Nozaka, Carley Johnson","doi":"10.5194/sd-31-71-2022","DOIUrl":"https://doi.org/10.5194/sd-31-71-2022","url":null,"abstract":"Abstract. We report a new sampling strategy for collecting representative samples of\u0000drill core. By splitting the core with a diamond saw into working and\u0000archive halves, the saw cuttings constitute a “channel” sample, the best\u0000subsample from which to obtain an average mineralogical and geochemical\u0000composition of a core. We apply this procedure to sampling core of the lower oceanic crust in the Hess Deep obtained during Expedition 345 of the\u0000Integrated Ocean Drilling Program (now International Ocean Discovery\u0000Program). Our results show that particles produced by sawing range from sand to clay\u0000sizes. Sand- and silt-sized cuttings can be sampled with a spatula, whereas\u0000clay-sized particles remained in suspension after 12 h and could be\u0000collected only by settling, aided by centrifuge. X-ray diffraction (XRD) analysis and Rietveld\u0000refinement show that phyllosilicates were fractionated into the clay-sized\u0000fraction. Thus, collection of both the sedimented fraction and the clay-sized suspended fraction (commonly > 15 wt % of the total) is\u0000necessary to capture the whole sample. The strong positive correlation\u0000between the recovered sample mass (in grams) and length of core cut demonstrates\u0000that this sampling protocol was uniform and systematic, with almost 1.4 g\u0000sediment produced per centimeter of core cut. We show that major-element\u0000concentrations of our channel samples compare favorably with the\u0000compositions of billet-sized samples analyzed aboard the JOIDES Resolution,\u0000but the results show that individual billet analyses are rarely\u0000representative of the whole core recovered. A final test of the validity of\u0000our methods comes from the strong positive correlation between the loss on\u0000ignition (LOI) values of our channel samples and the H2O contents\u0000calculated from the modal mineralogy obtained by X-ray diffraction and\u0000Rietveld refinement. This sampling procedure shows that grain-sized\u0000fractionation modifies both mineralogical and chemical compositions;\u0000nevertheless, this channel sampling method is a reliable method of obtaining\u0000representative samples of bulk cores. With the ever-increasing precision\u0000offered by modern analytical instrumentation, this sampling protocol allows\u0000the accuracy of the analytical results to keep pace.\u0000","PeriodicalId":51840,"journal":{"name":"Scientific Drilling","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88532755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mediterranean–Black Sea gateway exchange: scientific drilling workshop on the BlackGate project","authors":"W. Krijgsman, I. Vasiliev, A. Beniest, T. Lyons, J. Lofi, G. Tari, C. Slomp, N. Cagatay, M. Triantaphyllou, R. Flecker, D. Palcu, C. McHugh, H. Arz, P. Henry, Karen J. Lloyd, G. Çifçi, Ö. Sipahioglu, D. Sakellariou","doi":"10.5194/sd-31-93-2022","DOIUrl":"https://doi.org/10.5194/sd-31-93-2022","url":null,"abstract":"Abstract. The MagellanPlus workshop “BlackGate” addressed fundamental questions\u0000concerning the dynamic evolution of the Mediterranean–Black Sea (MBS)\u0000gateway and its palaeoenvironmental consequences. This gateway drives the\u0000Miocene–Quaternary circulation patterns in the Black Sea and governs its\u0000present status as the world's largest example of marine anoxia. The exchange\u0000history of the MBS gateway is poorly constrained because continuous\u0000Pliocene–Quaternary deposits are not exposed on land adjacent to the Black\u0000Sea or northern Aegean. Gateway exchange is controlled by climatic\u0000(glacio-eustatic-driven sea-level fluctuations) and tectonic processes in\u0000the catchment as well as tectonic propagation of the North Anatolian Fault\u0000Zone (NAFZ) in the gateway area itself. Changes in connectivity trigger\u0000dramatic palaeoenvironmental and biotic turnovers in both the Black Sea and\u0000Mediterranean domains. Drilling a Messinian to Holocene transect across the\u0000MBS gateway will recover high-amplitude records of continent-scale\u0000hydrological changes during glacial–interglacial cycles and allow us to\u0000reconstruct marine and freshwater fluxes, biological turnover events, deep\u0000biospheric processes, subsurface gradients in primary sedimentary\u0000properties, patterns and processes controlling anoxia, chemical\u0000perturbations and carbon cycling, growth and propagation of the NAFZ, the\u0000timing of land bridges for Africa and/or Asia–Europe mammal migration, and the\u0000presence or absence of water exchange during the Messinian salinity crisis.\u0000During thorough discussions at the workshop, three key sites were selected\u0000for potential drilling using a mission-specific platform (MSP): one on the\u0000Turkish margin of the Black Sea (Arkhangelsky Ridge, 400 m b.s.f., metres below the seafloor), one on the\u0000southern margin of the Sea of Marmara (North İmrali Basin, 750 m b.s.f.), and one\u0000in the Aegean (North Aegean Trough, 650 m b.s.f.). All sites target Quaternary\u0000oxic–anoxic marl–sapropel cycles. Plans include recovery of Pliocene\u0000lacustrine sediments and mixed marine–brackish Miocene sediments from the\u0000Black Sea and the Aegean. MSP drilling is required because the JOIDES Resolution\u0000cannot pass under the Bosporus bridges. The wider goals are in line with the\u0000aims and scope of the International Ocean Discovery Program (IODP) “2050 Science Framework: Exploring Earth by\u0000Scientific Ocean Drilling” and relate specifically to the strategic\u0000objectives “Earth's climate system”, “Tipping points in Earth's history”, and\u0000“Natural hazards impacting society”.\u0000","PeriodicalId":51840,"journal":{"name":"Scientific Drilling","volume":"9 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82442283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ICDP drilling of the Eger Rift observatory: magmatic fluids driving the earthquake swarms and deep biosphere","authors":"T. Fischer, P. Hrubcová, T. Dahm, H. Woith, T. Vylita, M. Ohrnberger, J. Vlček, J. Horalek, P. Dědeček, M. Zimmer, M. Lipus, S. Pierdominici, J. Kallmeyer, F. Krüger, K. Hannemann, M. Korn, H. Kämpf, T. Reinsch, Jakub Klicpera, D. Vollmer, K. Daskalopoulou","doi":"10.5194/sd-31-31-2022","DOIUrl":"https://doi.org/10.5194/sd-31-31-2022","url":null,"abstract":"Abstract. The new in situ geodynamic laboratory established in the framework of the ICDP Eger project aims to develop the most modern, comprehensive, multiparameter laboratory at depth for studying earthquake swarms, crustal fluid flow, mantle-derived CO2 and helium degassing, and processes of the deep biosphere. In order to reach a new level of high-frequency, near-source and\u0000multiparameter observation of earthquake swarms and related phenomena,\u0000such a laboratory comprises a set of shallow boreholes with high-frequency\u00003-D seismic arrays as well as modern continuous real-time fluid\u0000monitoring at depth and the study of the deep biosphere. This laboratory is located in the western part of the Eger Rift at the\u0000border of the Czech Republic and Germany (in the West Bohemia–Vogtland\u0000geodynamic region) and comprises a set of five boreholes around the\u0000seismoactive zone. To date, all monitoring boreholes have been drilled. This\u0000includes the seismic monitoring boreholes S1, S2 and S3 in the crystalline\u0000units north and east of the major Nový Kostel seismogenic zone,\u0000borehole F3 in the Hartoušov mofette field and borehole S4 in the\u0000newly discovered Bažina maar near Libá. Supplementary borehole P1 is being prepared in the Neualbenreuth maar for paleoclimate and biological\u0000research. At each of these sites, a borehole broadband seismometer will be\u0000installed, and sites S1, S2 and S3 will also host a 3-D seismic array\u0000composed of a vertical geophone chain and surface seismic array. Seismic\u0000instrumenting has been completed in the S1 borehole and is in preparation in the\u0000remaining four monitoring boreholes. The continuous fluid monitoring site of\u0000Hartoušov includes three boreholes, F1, F2 and F3, and a pilot monitoring phase is underway. The laboratory also enables one to analyze microbial activity at CO2 mofettes and maar structures in the context of changes in habitats. The drillings into the maar volcanoes contribute to a better understanding of the Quaternary paleoclimate and volcanic activity.\u0000","PeriodicalId":51840,"journal":{"name":"Scientific Drilling","volume":"43 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81397844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Drilling Overdeepened Alpine Valleys (ICDP-DOVE): quantifying the age, extent, and environmental impact of Alpine glaciations","authors":"F. Anselmetti, M. Bavec, C. Crouzet, M. Fiebig, G. Gabriel, F. Preusser, C. Ravazzi","doi":"10.5194/sd-31-51-2022","DOIUrl":"https://doi.org/10.5194/sd-31-51-2022","url":null,"abstract":"Abstract. The sedimentary infill of glacially overdeepened valleys\u0000(i.e., structures eroded below the fluvial base level) is an excellent but\u0000yet underexplored archive with regard to the age, extent, and nature of past glaciations. The ICDP project DOVE (Drilling Overdeepened Alpine Valleys) Phase 1 investigates a series of drill cores from glacially overdeepened troughs at several locations along the northern front of the Alps. All sites\u0000will be investigated with regard to several aspects of environmental\u0000dynamics during the Quaternary, with focus on the glaciation, vegetation,\u0000and landscape history. Geophysical methods (e.g., seismic surveys), for\u0000example, will explore the geometry of overdeepened structures to better\u0000understand the process of overdeepening. Sedimentological analyses combined\u0000with downhole logging, analysis of biological remains, and state-of-the-art\u0000geochronological methods, will enable us to reconstruct the erosion and\u0000sedimentation history of the overdeepened troughs. This approach is expected\u0000to yield significant novel data quantifying the extent and timing of Middle\u0000and Late Pleistocene glaciations of the Alps. In a first phase, two sites\u0000were drilled in late 2021 into filled overdeepenings below the\u0000paleolobe of the Rhine Glacier, and both recovered a trough filling composed\u0000of multiphase glacial sequences. Fully cored Hole 5068_1_C reached a depth of 165 m and recovered 10 m molasse bedrock at the base. This hole will be used together with two flush holes (5068_1_A, 5068_1_B) for further geophysical cross-well experiments. Site 5068_2 reached a depth of 255 m\u0000and bottomed out near the soft rock–bedrock contact. These two sites are\u0000complemented by three legacy drill sites that previously recovered filled\u0000overdeepenings below the more eastern Alpine Isar-Loisach, Salzach, and Traun paleoglacier lobes (5068_3, 5068_4, 5068_5). All analysis and\u0000interpretations of this DOVE Phase 1 will eventually lay the ground for an\u0000upcoming Phase 2 that will complete the pan-Alpine approach. This follow-up\u0000phase will investigate overdeepenings formerly occupied by paleoglacier\u0000lobes from the western and southern Alpine margins through drilling sites in France, Italy, and Slovenia. Available geological information and\u0000infrastructure make the Alps an ideal area to study overdeepened structures;\u0000however, the expected results of this study will not be restricted to the\u0000Alps. Such features are also known from other formerly glaciated mountain\u0000ranges, which are less studied than the Alps and more problematic with\u0000regards to drilling logistics. The results of this study will serve as\u0000textbook concepts to understand a full range of geological processes\u0000relevant to formerly glaciated areas all over our planet.\u0000","PeriodicalId":51840,"journal":{"name":"Scientific Drilling","volume":"50 2 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81583088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"60 years of scientific deep drilling in Colombia: the north Andean guide to the Quaternary","authors":"H. Hooghiemstra, G. Pérez, Vladimir Torres Torres, J. Berrío, L. Lourens, S. Flantua","doi":"10.5194/sd-30-1-2022","DOIUrl":"https://doi.org/10.5194/sd-30-1-2022","url":null,"abstract":"Abstract. We sketch the initial history of collecting deep cores in terrestrial and marine sedimentary basins and ice cores to study environmental and climate change. Subsequently, we focus on the development of long records from the Northern Andes. The 586 m long pollen record from ancient Lake Bogotá reflects the last 2.25 × 106 years with ∼ 1.2 kyr resolution, whereas the sediment core reflects almost the complete Quaternary. The 58 m long composite core from Lake Fúquene covers the last 284 ka with ∼ 60 years resolution. We address the various challenges and limitations of working with deep continental cores. For the tropics, the presence of these deep cores has made the Northern Andes a key area in developing and testing hypotheses in the fields of ecology, paleobiogeography, and climate change. We summarize the results in the figures, and for details on the paleoenvironmental reconstructions, we refer to the corresponding literature. We provide an overview of the literature on long continental records from all continents (see the Supplement). Based on our 50 years of experience in continental core drilling, developing a research capacity to analyze the large amounts of samples, and keeping a team together to publish the results, we listed suggestions in support of deep continental records aimed at studying environmental and climate change over long intervals of time.\u0000","PeriodicalId":51840,"journal":{"name":"Scientific Drilling","volume":"62 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80155451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ship-board determination of whole-rock (ultra-)trace element concentrations by laser ablation-inductively coupled plasma mass spectrometry analysis of pressed powder pellets aboard the D/V <i>Chikyu</i>","authors":"M. Rospabé, F. Kourim, A. Tamura, E. Takazawa, M. Giampouras, S. Chatterjee, K. Ishii, M. Cooper, M. Godard, E. Carter, N. Abe, K. Moe, D. Teagle","doi":"10.5194/sd-30-75-2022","DOIUrl":"https://doi.org/10.5194/sd-30-75-2022","url":null,"abstract":"Abstract. The Oman Drilling Project (OmanDP), performed under the\u0000International Continental Scientific Drilling Program (ICDP), is an\u0000international scientific research project that undertook drilling at a range of sites in the Semail ophiolite (Oman) to collect core samples spanning the stratigraphy of the ophiolite, from the upper oceanic crust down to the basal thrust. The cores were logged to International Ocean Discovery Program (IODP) standards aboard the D/V Chikyu. During ChikyuOman2018 Leg 3 (July–August 2018), participants described cores from the crust–mantle transition (CM) sites. The main rock types recovered at these sites were\u0000gabbros, dunites and harzburgites, rocks typically forming the base of the\u0000oceanic crust and the shallow mantle beneath present-day spreading centres.\u0000In addition to the core description, selected samples were analysed by X-ray fluorescence spectrometry (XRF) for their chemical compositions, including major, minor and some trace elements. To complement these standard procedures, we developed new\u0000approaches to measure ultra-trace element concentrations using a procedure\u0000adapted from previous works to prepare fine-grained pressed powder pellets\u0000coupled with laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis using instrumentation aboard the D/V Chikyu. First, three (ultra)mafic reference materials were investigated to test and validate our procedure (BHVO-2, BIR-1a and JP-1), and then the procedure was applied to a selection of gabbro and dunite samples from the CM cores to\u0000explore the limitations of the method in its current stage of development.\u0000The obtained results are in good agreement with preferred values for the\u0000reference materials and with subsequent solution replicate analyses of the same samples performed in shore-based laboratories following Leg 3 for the\u0000CM samples. We describe this procedure for the determination of 37 minor and (ultra-)trace elements (transition elements and Ga, Li and Large-Ion Lithophile Elements (LILE), Rare Earth Elements (REE), High-Field-Strength Elements (HFSE), U, Th, and Pb) in mafic and ultramafic rocks. The presented method has the major advantage that it allows the determination at sea of the\u0000(ultra-)trace element concentrations in a “dry”, safe way, without using\u0000acid reagents. Our new approach could be extended for other elements of\u0000interest and/or be improved to be adapted to other rock materials during\u0000future ocean drilling operations aboard the D/V Chikyu and other platforms.\u0000","PeriodicalId":51840,"journal":{"name":"Scientific Drilling","volume":"28 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87999437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sensitivity of the West Antarctic Ice Sheet to +2 °C (SWAIS 2C)","authors":"M. Patterson, R. Levy, D. Kulhanek, T. van de Flierdt, H. Horgan, G. Dunbar, T. Naish, Jeanine Ash, A. Pyne, Darcy Mandeno, P. Winberry, D. Harwood, F. Florindo, F. Jiménez-Espejo, A. Läufer, K. Yoo, O. Seki, P. Stocchi, J. Klages, Jae Il Lee, F. Colleoni, Y. Suganuma, E. Gasson, C. Ohneiser, J. Flores, D. Try, R. Kirkman, Daleen Koch","doi":"10.5194/sd-30-101-2022","DOIUrl":"https://doi.org/10.5194/sd-30-101-2022","url":null,"abstract":"Abstract. The West Antarctic Ice Sheet (WAIS) presently holds enough ice to raise global sea level by 4.3 m if completely melted. The unknown\u0000response of the WAIS to future warming remains a significant challenge for\u0000numerical models in quantifying predictions of future sea level rise. Sea\u0000level rise is one of the clearest planet-wide signals of human-induced\u0000climate change. The Sensitivity of the West Antarctic Ice Sheet to a Warming\u0000of 2 ∘C (SWAIS 2C) Project aims to understand past and current\u0000drivers and thresholds of WAIS dynamics to improve projections of the rate\u0000and size of ice sheet changes under a range of elevated greenhouse gas\u0000levels in the atmosphere as well as the associated average global\u0000temperature scenarios to and beyond the +2 ∘C target of the\u0000Paris Climate Agreement. Despite efforts through previous land and ship-based drilling on and along\u0000the Antarctic margin, unequivocal evidence of major WAIS retreat or collapse and its causes has remained elusive. To evaluate and plan for the\u0000interdisciplinary scientific opportunities and engineering challenges that\u0000an International Continental Drilling Program (ICDP) project along the Siple coast near the grounding zone of the WAIS could offer (Fig. 1), researchers, engineers, and logistics providers representing 10 countries held a virtual\u0000workshop in October 2020. This international partnership comprised of\u0000geologists, glaciologists, oceanographers, geophysicists, microbiologists,\u0000climate and ice sheet modelers, and engineers outlined specific research\u0000objectives and logistical challenges associated with the recovery of Neogene and Quaternary geological records from the West Antarctic interior adjacent to the Kamb Ice Stream and at Crary Ice Rise. New geophysical surveys at these locations have identified drilling targets in which new drilling technologies will allow for the recovery of up to 200 m of sediments beneath\u0000the ice sheet. Sub-ice-shelf records have so far proven difficult to obtain\u0000but are critical to better constrain marine ice sheet sensitivity to past\u0000and future increases in global mean surface temperature up to 2 ∘C\u0000above pre-industrial levels. Thus, the scientific and technological advances developed through this program will enable us to test whether WAIS collapsed during past intervals of warmth and determine its sensitivity to a +2 ∘C global warming threshold (UNFCCC, 2015).\u0000","PeriodicalId":51840,"journal":{"name":"Scientific Drilling","volume":"13 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90596872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of sediment composition by smear slides to quantitative shipboard data: a case study on the utility of smear slide percent estimates, IODP Expedition 353, northern Indian Ocean","authors":"S. Phillips, K. Littler","doi":"10.5194/sd-30-59-2022","DOIUrl":"https://doi.org/10.5194/sd-30-59-2022","url":null,"abstract":"Abstract. Smear slide petrography has been a standard technique during scientific ocean drilling expeditions to characterize sediment composition and classify sediment types, but presentation of these percent\u0000estimates to track downcore trends in sediment composition has become less\u0000frequent over the past 2 decades. We compare semi-quantitative smear slide composition estimates to physical property (natural gamma radiation, NGR)\u0000and solid-phase geochemical (calcium carbonate, CaCO3 %)\u0000measurements from a range of marine depositional environments in the\u0000northern Indian Ocean (Bay of Bengal, Andaman Sea, Ninetyeast Ridge)\u0000collected during International Ocean Discovery Program (IODP) Expedition 353. We show that presenting smear slide estimates as percentages, rather\u0000than abundance categories, reveals similar downcore variation in composition\u0000to the more quantitative core analyses. Overall downcore trends in total calcareous components from smear slides (foraminifers + nannofossils +\u0000shell fragments + authigenic carbonate) follow similar downcore trends to samples measured by CaCO3 coulometry. Total lithogenic components\u0000(clay + mica + quartz + feldspars + lithic grains + vitric grains\u0000+ glauconite + heavy minerals + iron oxides) and clay from smear\u0000slides track reasonably well with NGR measurements. Comparison of site\u0000averages of absolute percentages of total calcium carbonate from coulometry\u0000and total calcareous components from smear slide observations reveals an overestimation in carbonate percentages in smear slides (likely due in part\u0000to underestimation of the clay fraction), especially in sediments rich in smectite clays. Differences in sediment color between sites and settling of\u0000clay particles during slide preparation may contribute to this discrepancy.\u0000Although smear slide estimates range in accuracy depending on the training\u0000of the operator, we suggest that sedimentologists describing cores obtained\u0000during scientific drilling can use the percent estimates of sedimentary\u0000components in smear slides to identify trends and cyclicity in marine\u0000sediment records.\u0000","PeriodicalId":51840,"journal":{"name":"Scientific Drilling","volume":"33 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78957508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From glacial erosion to basin overfill: a 240 m-thick overdeepening–fill sequence in Bern, Switzerland","authors":"M. Schwenk, P. Schläfli, D. Bandou, Natacha Gribenski, G. Douillet, F. Schlunegger","doi":"10.5194/sd-30-17-2022","DOIUrl":"https://doi.org/10.5194/sd-30-17-2022","url":null,"abstract":"Abstract. We drilled a 210 m-thick succession of Quaternary sediments and extended it 30 m upsection with information that we collected from an adjacent outcrop. In the 240 m-thick succession we identified 12 different lithofacies, grouped them into five facies assemblages, and distinguished two major sedimentary sequences. A sharp contact at 103 m depth cuts off cross-beds in sequence A and separates them from the overlying horizontal beds in sequence B. Although the lowermost facies assemblage of each sequence includes a till deposited during a period of ice cover, the two tills differ from each other. In particular, the till at the base of sequence A is dominated by large clasts derived from the underlying Molasse bedrock, whereas the till at the base of sequence B has no such Molasse components. Furthermore, the till in sequence A bears evidence of glaciotectonic deformation. Both tills are overlain by thick assemblages of subaqueous, most likely glaciolacustrine and lacustrine facies elements. The cross-bedded and steeply inclined sand, gravel, and diamictic beds of sequence A are interpreted as deposits of density currents in a subaqueous ice-contact fan system within a proglacial lake. In contrast, the lacustrine sediments in sequence B are considered to record a less energetic environment where the material was most likely deposited in a prodelta setting that gradually developed into a delta plain. Towards the top, sequence B evolves into a fluvial system recorded in sequence C, when large sediment fluxes of a possibly advancing glacier resulted in a widespread cover of the region by a thick gravel unit. Feldspar luminescence dating on two samples from a sand layer at the top of sequence B provided uncorrected ages of 250.3 ± 80.2 and 251.3 ± 59.8 ka. The combination of these ages with lithostratigraphic correlations of sedimentary sequences encountered in neighboring scientific drillings suggests that sequence B was deposited between Marine Isotope Stage 8 (MIS 8; 300–243 ka) and MIS 7 (243–191 ka). This depositional age marks the end of one stage of overdeepening–fill in the perialpine Aare Valley near Bern.\u0000","PeriodicalId":51840,"journal":{"name":"Scientific Drilling","volume":"20 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78960656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}