32 research outputs found
Characterization of clay minerals and Fe oxides through diffuse reflectance spectroscopy (VNIR-SWIR)
[ES] Se ha realizado el análisis mineralógico a través de las propiedades espectrales desarrolladas por muestras de suelos y sedimentos del borde noroccidental de la Cuenca del Duero. Las absorciones producidas por los óxidos y oxihidróxidos de hierro (hematites y goethita, principalmente) están localizadas en zonas del VNIR (400-1200 nm), mientras que las bandas de absorción presentes en los espectros del SWIR (1200-2500 nm) están relacionadas con la composición química de minerales arcillosos. Los espectros de reflectancia medidos en laboratorio han sido normalizados aplicando los métodos del Continuum Removal (CR) y la segunda derivada (SD). Este último puede resolver la superposición de bandas al cuantificar sutiles inflexiones de la curva. Esto ha permitido examinar las bandas de absorción por separado midiendo los parámetros geométricos desarrollados en ellas. La proporción de los minerales influye en la respuesta espectral y, por tanto, en los valores de los parámetros. Se han realizado correlaciones lineales entre estos valores y la proporción de las diferentes fases minerales obtenidas por difracción de rayos X. De los parámetros estudiados, la correlación entre la posición del centro de banda (BC) en la máxima absorción alrededor de longitudes de onda de 890-960 nm y la profundidad del rasgo de absorción a 470 nm (D470) ha permitido realizar una estimación relativa de la proporción de hematites/goethita. En cuanto a la distribución de los diferentes minerales de arcilla, se ha podido establecer una correlación entre la proporción de caolinita y la profundidad de las bandas de absorción a 1415 y 2210 nm, y en los rasgos de absorción cercanos a 1390 y 2160 nm, analizados en SD.[EN] The mineralogical analysis was carried out through the spectral properties developed by samples of soils and sediments from the northwestern edge of the Duero Basin. The absorptions produced by the oxides and Feoxyhydroxides (mainly hematite and goethite) are located in VNIR zones (400-1200 nm), while the absorption bands that are present in the SWIR spectra (1200-2500 nm) are related to the chemical composition of clay minerals. The reflectance spectra measured in the laboratory have been normalized by using the methods of Continuum Removal (CR) and the second derivative (SD). This last method can solve the band overlapping because it quantifies subtle drops in the curve. This has allowed the absorption bands to be examined separately by measurement of their geometrical parameters. The proportion of the minerals affects the spectral response and, accordingly, the values of the parameters. Linear correlations were conducted between these values and the proportion of the different mineral phases obtained by X-ray diffraction. In the studied parameters, the correlation between the band center (BC) position in the maximum absorption around the wavelengths at 890-960 nm and the absorption feature depth at 470 nm (D470) has enabled a relative estimation of the proportion of hematite/goethite. As for the distribution of the different clay minerals, a correlation has been established between the proportion of kaolinite and the absorption bands depth at 1415 and 2210 nm, and in the absorption features near 1390 and 2160 nm, analyzed in SD.Trabajo financiado por los Proyectos CGL2016-77005-R y ESP2017-89045-R del Ministerio de
Ciencia, Innovación y Universidades, y el ProyectoLE169G18 de la Junta de Castilla y León.Báscones, A.; Suárez, M.; Ferrer-Julià, M.; García-Meléndez, E.; Colmenero-Hidalgo, E.; Quirós, A. (2020). Caracterización de minerales de arcilla y óxidos de hierro mediante espectroscopía de reflectancia difusa (VNIR–SWIR). Revista de Teledetección. 0(55):49-57. https://doi.org/10.4995/raet.2020.13331OJS4957055Ben-Dor, E., Banin, A. 1995. Near-infrared analysis as a rapid method to simultaneously evaluate several soil properties. Soil Science Society of America Journal, 59(2), 364-37. https://doi.org/10.2136/ sssaj1995.03615995005900020014xBen-Dor, E. 2002. Quantitative remote sensing of soil properties. Advances in Agronomy, 75, 173-243. https://doi.org/10.1016/S0065-2113(02)75005-0Bishop, J.L., Lane, M.D., Dyar, M.D., Brown, A.J. 2008. Reflectance and emission spectroscopy study of four groups of phyllosilicates: smectites, kaolinite-serpentines, chlorites and micas. Clay Minerals, 43, 35- 54. https://doi.org/10.1180/claymin.2008.043.1.03Brown, D.J., Shepherd, K.D., Walsh, M.G., Dewayne Mays, M., Reinsch, T.G. 2006. Global soil characterization with VNIR diffuse reflectance spectroscopy. Geoderma, 132, 273-290. https://doi.org/10.1016/j.geoderma.2005.04.025Burns, R.G. 1993. Mineralogical Applications of Crystal Field Theory. Cambridge: Cambridge University Press. https://doi.org/10.1017/CBO9780511524899Cariati, F., Erre, L., Micera, G., Piu, P., Gessa, C. 1981. Water molecules and hydroxyl groups in montmorillonites as studied by near infrared spectroscopy. Clays and Clay Minerals, 29, 157- 159. https://doi.org/10.1346/CCMN.1981.0290211Clark, R.N., Roush, T.L. 1984. Reflectance spectroscopy: quantitative analysis techniques for remote sensing applications. Journal of Geophysical Research, 89, 6329-6340. https://doi.org/10.1029/JB089iB07p06329Clark, R.N., King, T.V.V., Klejwa, M., Swayze, G., Vergo, N. 1990. 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Relación entre la respuesta espectral (visible-infrarrojo cercano) y la composición mineralógica de materiales sedimentarios del borde occidental de la Cuenca del Duero. Rev. Soc. Geol. España, 17(1-2), 39-47.García-Rivas, J., Suárez, M., García-Romero, E., García-Meléndez, E. 2018. Identification and classification of mineralogical associations by VNIR-SWIR spectroscopy in the Tajo basin (Spain). International Journal of Applied Earth Observations and Geoinformation, 72, 57-65. https://doi.org/10.1016/j.jag.2018.05.028González Menéndez, L., Heredia, N., Marcos, A. 2008. Mapa Geológico Digital continuo E. 1:50000, Zona Asturoccidental-Leonesa (Zona-1100). En: GEODE. Mapa Geológico Digital continuo de España, Cartografía del IGME.Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L. y Klein, A.J. 2017. USGS Spectral Library Version 7. U.S. Geological Survey Data Series 1035, 61pp. https://doi.org/10.3133/ds1035Martín Pozas, J.M. 1975. Análisis cuantitativo de fases cristalinas por DRX. En: Difracción de muestras policristalinas. Método de Debye-Scherrer, J.A. Saja, ed., I.C.E. Universidad de Valladolid.Moore, D.M., Reynolds, R.C. 1997. X-ray diffraction and identification and analysis of clay minerals. 2nd Edition, Oxford University Press, New York.Pérez García, L.C. 1977. Los Sedimentos Auríferos del NO de la Cuenca del Duero (Provincia de León, España) y su Prospección. Tesis Doctoral, Universidad de Oviedo.Petit, S., Madejová, J., Decarreau, A., Martin, F. 1999. Characterization of octahedral substitutions in kaolinites using near Infrared spectroscopy. Clays and Clay Minerals, 47, 103-108. https://doi.org/10.1346/CCMN.1999.0470111Petit, S., Decarreau, A., Martin, F., Buchetet, R. 2004. Refined relationship between the position of the fundamental OH stretching and the first overtones for clays. Phys. Chem. Minerals, 31, 585-592. https://doi.org/10.1007/s00269-004-0423-xRiaza, A., García-Meléndez, E., Suárez, M., Hausold, A., Beisl, U., Van Der Werff, H., Pascual, L. 2004. Climate-dependent iron bearing morphological units around lake marshes (Tablas de Daimiel, Spain) using hyperspectral DAIS 7915 and ROSIS Spectrometer data. Proceedings of SPIE - the international society for optical engineering, 5239, 322-332. https://doi.org/10.1117/12.511810Scheinost, A.C., Chavernas, A., Barrón V., Torrent, J. 1998 Use and limitations of second-derivative diffuse reflectance spectroscopy in the visible to near-infrared range to identify and quantify Fe oxide minerals in soils. Clays and Clay Minerals, 46, 528- 536. https://doi.org/10.1346/CCMN.1998.0460506Sherman, D.M., Waite, T.D., 1985. Electronic spectra of Fe3+ oxides and oxide hydroxides in the near IR to near UV. American Mineralogist, 70, 1262-1269.Stenberg, B., Viscarra Rossel, R.A., Mouazen, A.M., Wetterlind, J. 2010. Visible and near infrared spectroscopy in soil science. Advances in Agronomy, 107, 163-215. https://doi.org/10.1016/S0065-2113(10)07005-7Van der Meer, F. 2004. Analysis of spectral absorption features in hyperspectral imagery. International Journal of Applied Earth Observation and Geoinformation, 5, 55-68. https://doi.org/10.1016/j.jag.2003.09.001Villar Alonso, P., Portero Urroz, G., González Cuadra, P., García Crespo J., Nieto García, A.B., Rubio Pascual, F.J., Gómez Fernández, F., Jiménez Benayas, S. 2005. Mapa Geológico Digital continuo E. 1:50000, Zona Centroibérica. Dominio Ollo de Sapo (Zona-1300). En: GEODE. Mapa Geológico Digital continuo de España, Cartografía del IGME.Viscarra Rossel, R.A., McGlynn, R.N., McBratney, A.B. 2006. Determining the composition of mineral-organic mixes using UV-vis-NIR diffuse reflectance spectroscopy. Geoderma, 137, 70-82. https://doi.org/10.1016/j.geoderma.2006.07.004Viscarra Rossel, R.A., Cattle, S.R., Ortega, A., Fouad, Y. 2009. In situ measurements of soil colour, mineral composition and clay content by vis- NIR spectroscopy. Geoderma, 150, 253-266. https://doi.org/10.1016/j.geoderma.2009.01.025Viscarra Rossel, R.A., Bui, E.N., de Caritat, P., McKenzie, N.J., 2010. Mapping iron oxides and the color of Australian soil using visible-near-infrared reflectance spectra, J. Geophys. Res., 115, F04031. https://doi.org/10.1029/2009JF00164
Evidence for a multi-species coccolith volume change over the past two centuries: understanding a potential ocean acidification response
Major questions surround the species-specific nature of coccolithophore calcification in response to rising atmospheric CO2 levels. Here we present CaCO3 particle volume distribution data from the coccolith size-fraction of a rapidly accumulating North Atlantic sediment core. Without direct volume measurements on coccoliths produced by individual coccolithophore species, and knowledge of organic, as well as inorganic carbon production, it is not possible to state conclusively the coccolithophore calcification change at this site. However, by analysing the size distribution of CaCO3 particles in the less than 10 μm sediment fraction, we demonstrate a changing particle volume since the late 20th Century consistent with an increase in the mass of coccoliths produced by the larger coccolithophore species, and potentially a decrease in mass of coccoliths produced by the smaller species, present at this location. This finding has significant implications for the realistic representation of an assemblage-wide coccolithophore CO2-calcification response in numerical models
Impact of iceberg melting on Mediterranean thermohaline circulation during Heinrich events
Down-core samples of planktonic and benthic foraminifera were analyzed for oxygen and carbon isotopes in International Marine Past Global Changes Study (IMAGES) core MD99-2343 in order to study the interactions between climate change in the Northern Hemisphere and the western Mediterranean thermohaline circulation at times of Heinrich events (HE). Our results confirm the antiphase correlation between enhanced North Atlantic Deep Water formation and low ventilation in the Mediterranean. However, this study reveals that this antiphase relationship in deepwater formation between the North Atlantic and Mediterranean was interrupted during times of HE when the injection of large volumes of water from melting icebergs reached the entrance to the Mediterranean. These events, which lasted less than 1000 years, are represented by pronounced decreases in both planktonic d18O and benthic d13C signals. Lower salinities of Mediterranean surface water resulted in a slowdown of western Mediterranean deepwater overturn even though cold sea surface temperatures and drier climate should have resulted in enhanced deepwater formation
Evidence for a multi-species coccolith volume change over the past two centuries: understanding a potential ocean acidification response
Major questions surround the species-specific nature of coccolithophore calcification in response to rising atmospheric CO<sub>2</sub> levels. Here we present CaCO<sub>3</sub> particle volume distribution data from the coccolith size-fraction of a rapidly accumulating North Atlantic sediment core. Without direct volume measurements on coccoliths produced by individual coccolithophore species, and knowledge of organic, as well as inorganic carbon production, it is not possible to state conclusively the coccolithophore calcification change at this site. However, by analysing the size distribution of CaCO<sub>3</sub> particles in the less than 10 μm sediment fraction, we demonstrate a changing particle volume since the late 20th Century consistent with an increase in the mass of coccoliths produced by the larger coccolithophore species, and potentially a decrease in mass of coccoliths produced by the smaller species, present at this location. This finding has significant implications for the realistic representation of an assemblage-wide coccolithophore CO<sub>2</sub>-calcification response in numerical models
A multi-species coccolith volume response to an anthropogenically-modified ocean
Major questions surround the species-specific nature of coccolithophore calcification in response to rising atmospheric CO2 levels. Here we present CaCO3 particle volume distribution data from the coccolith size-fraction of a rapidly accumulating North Atlantic sediment core. These data appear to indicate that coccoliths produced by the larger coccolithophore species present at this location increase in mass in parallel with anthropogenic CO2 release. This finding has significant implications for the realistic representation of an assemblage-wide coccolithophore CO2-calcification response in numerical models
Ocean surface water response to short-term climate changes revealed by coccolithophores from the Gulf of Cadiz (NE Atlantic) and Alboran Sea (W Mediterranean)
The response of coccolithophore assemblages to short-term millennial and centennial climatic changes over the last 50 kyr is studied in core M39029-7 from the Gulf of Cadiz (Atlantic Ocean) and core MD95-2043 from the Alboran Sea (Western Mediterranean Sea). The nannoplankton data are compared with oxygen isotopes, U37k′-SST and other biogeochemical and sedimentological proxies to obtain a new perspective of the paleoceanography and paleoecology of the area during these short-term climatic changes. Coccolithophores indicate that Heinrich events (HE) were characterised by the presence of cold, low salinity and turbid water masses on both sides of the Strait of Gibraltar. High abundances of the Lower Photic Zone (LPZ) species Florisphaera profunda in the Gulf of Cadiz synchronous with HE are interpreted as being an evidence of upper water-column stratification on the Atlantic side. These episodes coincided with input of terrigenous material, especially during H2. Surface waters during Dansgaard-Oeschger (DO) Stadials were also cold and turbid, while most of DO Interstadials were characterised by warm-water flora. The increase in small placoliths (small Gephyrocapsa and Emiliania huxleyi (4 μm), which is considered here as a cold-water indicator. The sharp decrease in large specimens of E. huxleyi related to the warming trend in the last deglaciation can be used as a biostratigraphic reference level that marks—at least approximately—the deglaciation and the beginning of the Holocene. Peaks of F. profunda are observed during Termination 1 (T1) in the Alboran Sea. They are isochronous with the “Organic-Rich Layer 1” recognised in the Western Mediterranean. In this interval, the water column of the region was stratified as a consequence of the global increase in the sea level following the deglaciation. Quantitative analyses of the coccolithophore assemblage allow us to interpret that coccolithophore production has been higher in the Alboran Sea than in the Gulf of Cadiz during the Holocene
Extreme depositional events on the NW-Barents Sea continental margin
The post Last Glacial Maximum depositional history of the Storfjorden and Kveithola trough-mouth fans in the
North-western Barents Sea has been investigated within two coordinated Spanish and Italian projects in the framework
of the International Polar Year (IPY) Activity 367, NICE STREAMS
Sediment facies analysis allowed the distinction of a number of depositional processes whose onset appears closely
related to ice stream’s dynamics, oceanographic patterns, and sea-level changes in response to climate change. Highly
consolidated glacigenic diamicton, deposited during glacial maxima on the upper slope, indicating ice streams grounded
at the shelf edge. Massive release of IRD was associated to increased calving rates with possible outer ice streams lift
off and collapse at the inception of deglaciation. The presence of a several meter-thick sequence of interlaminated
sediments deposited by subglacial outbursts of turbid meltwater (plumites) indicates rapid ice streams' melting and
retreat. Crudely-layered and heavily-bioturbated sediments deposited in the later stages of deglaciation by contour
currents under climatic/environmental conditions favourable to bioproductivity.
The extreme sedimentation rate of 3.4 cm a−1 calculated for the plumites from the upper-slope area indicates a
massive, nearly instantaneous (less than 150 years), terrigenous input corresponding to an outstanding meltwater event.
We indicate these interlaminated sediments to represent the high-latitude marine record of Meltwater Pulse 1a (MWP-
1a)
(Appendix A) Relative abundance of Emiliania huxleyi in sediment cores of the North Atlantic
The coccolithophore species Emiliania huxleyi is characterized by a wide range of sizes, which can be easily distinguished in the light microscope. In this study we have quantified the abundance of large (coccoliths > 4 µm in maximum length) E. huxleyi specimens during the last 25 kyr in sedimentary records from eleven cores and drill sites in the NE Atlantic and W Mediterranean Sea, to prove its usefulness in the reconstruction of water mass dynamics and biostratigraphic potential.
During the Last Glacial Maximum this large form, a cold-water indicator, was common in the NE Atlantic and Mediterranean, and its regional variation in abundance indicates a displacement of the climatic zones southwards in agreement with the development of ice sheets and sea ice in the Northern Hemisphere during this period. On the other hand, the gradient between northern and southern surface water masses in the Subtropical Gyre appears to have been more pronounced than at present, while the Portugal and Canary Currents were more intense. In the western Mediterranean basin temperatures were cooler than in the adjacent Atlantic, provoking a quasi-endemism of these specimens until the end of Heinrich Event 1. This may have been due to a restriction in the communication between the Atlantic and Mediterranean through the Strait of Gibraltar, the arrival of cold surface water and the amplification of cooling after the development of ice sheets in the Northern Hemisphere.
During the deglaciation, large E. huxleyi specimens decreased in abundance at medium and low latitudes, but were still numerous close to the Subarctic region during the Holocene. In transitional waters this decrease to present day abundances occurred after Termination Ib.
The abrupt change in abundance of this large E. huxleyi form is proposed as a new biostratigraphic event to characterize the Holocene in mid- to low-latitude water masses in the North Atlantic, although this horizon seems to be diachronous by 5 kyr from tropical to subarctic regions, in agreement with the gradual onset of warm conditions
Growth, dynamics and deglaciation of the last British–Irish ice sheet: the deep-sea ice-rafted detritus record
The evolution and dynamics of the last British–Irish Ice Sheet (BIIS) have hitherto largely been reconstructed from onshore and shallow marine glacial geological and geomorphological data. This reconstruction has been problematic because these sequences and data are spatially and temporally incomplete and fragmentary. In order to enhance BIIS reconstruction, we present a compilation of new and previously published ice-rafted detritus (IRD) flux and concentration data from high-resolution sediment cores recovered from the NE Atlantic deep-sea continental slope adjacent to the last BIIS. These cores are situated adjacent to the full latitudinal extent of the last BIIS and cover Marine Isotope Stages (MIS) 2 and 3. Age models are based on radiocarbon dating and graphical tuning of abundances of the polar planktonic foraminifera Neogloboquadrina pachyderma sinistral (% Nps) to the Greenland GISP2 ice core record. Multiple IRD fingerprinting techniques indicate that, at the selected locations, most IRD are sourced from adjacent BIIS ice streams except in the centre of Heinrich (H) layers in which IRD shows a prominent Laurentide Ice Sheet provenance. IRD flux data are interpreted with reference to a conceptual model explaining the relations between flux, North Atlantic hydrography and ice dynamics. Both positive and rapid negative mass balance can cause increases, and prominent peaks, in IRD flux. First-order interpretation of the IRD record indicates the timing of the presence of the BIIS with an actively calving marine margin. The records show a coherent latitudinal, but partly phased, signal during MIS 3 and 2. Published data indicate that the last BIIS initiated during the MIS 5/4 cooling transition; renewed growth just before H5 (46 ka) was succeeded by very strong millennial-scale variability apparently corresponding with Dansgaard–Oeschger (DO) cycles closely coupled to millennial-scale climate variability in the North Atlantic region involving latitudinal migration of the North Atlantic Polar Front. This indicates that the previously defined “precursor events” are not uniquely associated with H events but are part of the millennial-scale variability. Major growth of the ice sheet occurred after 29 ka with the Barra Ice Stream attaining a shelf-edge position and generating turbiditic flows on the Barra–Donegal Fan at ∼27 ka. The ice sheet reached its maximum extent at H2 (24 ka), earlier than interpreted in previous studies. Rapid retreat, initially characterised by peak IRD flux, during Greenland Interstadial 2 (23 ka) was followed by readvance between 22 and 16 ka. Readvance during H1 was only characterised by BIIS ice streams draining central dome(s) of the ice sheet, and was followed by rapid deglaciation and ice exhaustion. The evidence for a calving margin and IRD supply from the BIIS during Greenland Stadial 1 (Younger Dryas event) is equivocal. The timing of the initiation, maximum extent, deglacial and readvance phases of the BIIS interpreted from the IRD flux record is strongly supported by recent independent data from both the Irish Sea and North Sea sectors of the ice sheet
Seawater carbonate chemistry and processes during experiments with Emiliania huxleyi, 2008
Ocean acidification in response to rising atmospheric CO2 partial pressures is widely expected to reduce calcification by marine organisms. From the mid-Mesozoic, coccolithophores have been major calcium carbonate producers in the world's oceans, today accounting for about a third of the total marine CaCO3 production. Here, we present laboratory evidence that calcification and net primary production in the coccolithophore species Emiliania huxleyi are significantly increased by high CO2 partial pressures. Field evidence from the deep ocean is consistent with these laboratory conclusions, indicating that over the past 220 years there has been a 40% increase in average coccolith mass. Our findings show that coccolithophores are already responding and will probably continue to respond to rising atmospheric CO2 partial pressures, which has important implications for biogeochemical modeling of future oceans and climate