Person:
Rossi Nieto, Carlos

First Name

Carlos

Last Name

Rossi Nieto

URI

https://hdl.handle.net/20.500.14352/75285

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Geológicas

Department

Mineralogía y Petrología

Area

Petrología y Geoquímica

Identifiers

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Now showing 1 - 10 of 24

Manganese stromatolites in caves: El Soplao (Cantabria, Spain)
(Geology, 2010) Rossi Nieto, Carlos; Lozano, Rafael P.; Isanta, Nuria; Hellstrom, John
In the dark regions of caves, the formation of stromatolites is virtually unknown. Although Mn oxide crusts presumably induced by bacteria have been described in some caves, they lack stromatolite features, and the evidence of microbial origin is normally inconclusive. Here we describe for the first time the occurrence of extensive Mn oxide stromatolites formed in the deep interior of a cave. The stromatolites are of decimeter thickness and kilometer extent and show features extremely similar to typical CaCO3 stromatolites. However, unlike most stromatolites, their biogenicity is supported by the exceptional abundance of fossil microbes. Our data support that the stromatolites were mainly induced by chemolithotrophic Mn-oxidizing microbes, and were formed in a low-gradient water-table stream passage at least ~1 m.y. ago. The El Soplao stromatolites (Cantabria, Spain) may contribute to increasing our understanding of microbial life in extreme environments, as well as the role of bacteria in the genesis of modern and ancient Mn deposits.
Zaccagnaite-3R, a new Zn-Al hydrotalcite polytype from El Soplao cave (Cantabria, Spain)
(The American mineralogist, 2012) Lozano, Rafael Pablo; Rossi Nieto, Carlos; La Iglesia Fernández, Ángel; Matesanz, Emilio
We have recently discovered significant amounts of zaccagnaite, a natural Zn-Al-CO3 hydrotalcite in the El Soplao cave (north Spain). The El Soplao zaccagnaite is speleothemic, i.e., formed in the cave, and therefore it represents a new cave mineral. The origin of El Soplao zaccagnaite is related to the diagenesis of Zn- and Al-rich ferromanganese speleo-stromatolites, where it occurs as a porefilling cement that likely precipitated at low temperature (≤ ~11 °C). In some stromatolite layers, the abundance of zaccagnaite crystals is large enough to enable their physical separation. This has allowed us to obtain its X-ray powder-diffraction pattern, infrared spectrum, and differential thermal/thermogravimetric profiles. The cell parameters of the El Soplao zaccagnaite, refined from X-ray powder diffraction data are: a = 3.06616(1) and c = 22.6164(1) Å [α = β = 90°, γ = 120°; V = 184.139(1) Å3 ; Z = 3], consistent with a new trigonal polytype of zaccagnaite: zaccagnaite-3R. Besides, the El Soplao zaccagnaite shows some features previously unknown in natural hydrotalcites, such as octahedral-like morphologies and fluorescence zoning. Electron microprobe analyses revealed that the El Soplao zaccagnaite-3R has an unusual chemistry for natural hydrotalcites, as it is significantly more rich in Al (Zn2+/Al3+ = 1.6) than the hexagonal (2H) polytype (Zn2+/Al3+ = 2.0). The simplified chemical formula deduced from electron microprobe analysis is (Zn0.6Al0.4)(OH)2(CO3)0.2⋅0.5H2O, where C and water were calculated by stoichiometry. The carbon content calculated by stoichiometry (2.2 wt%) is in good agreement with that measured with the electron microprobe on gold-coated samples (2.5 wt%). The presence of interlayer water and CO3 groups was confirmed by thermogravimetric analysis coupled to mass spectroscopy, and by the analysis of the infrared spectrum.
Estromatolitos de manganeso en la cueva de El soplao (Cantabria)
(Enseñanza de las ciencias de la tierra, 2011) Rossi Nieto, Carlos; Lozano, Rafael Pablo; Isanta, Nuria
The 8.2 ka event in northern Spain: timing, structure and climatic impact from a multi-proxy speleothem record
(Climate of the past, 2022) Kilhavn, Hege; Couchoud, Isabelle; Drysdale, Russell; Rossi Nieto, Carlos; Hellstrom, John; Arnaud, Fabien; Wong, Henri
The 8.2 ka event is regarded as the most prominent climate anomaly of the Holocene and is thought to have been triggered by a meltwater release to the North Atlantic that was of sufficient magnitude to disrupt the Atlantic Meridional Overturning Circulation (AMOC). It is most clearly captured in Greenland ice-core records, where it is reported as a cold and dry anomaly lasting ∼ 160 years, from 8.25 ± 0.05 until 8.09 ± 0.05 ka (Thomas et al., 2007). It is also recorded in several archives in the North Atlantic region; however, its interpreted timing, evolution and impacts vary significantly. This inconsistency is commonly attributed to poorly constrained chronologies and/or inadequately resolved time series. Here we present a high-resolution speleothem record of early Holocene palaeoclimate from El Soplao Cave in northern Spain, a region pertinent to studying the impacts of AMOC perturbations on south-western Europe. We explore the timing and impact of the 8.2 ka event on a decadal scale by coupling speleothem stable carbon and oxygen isotopic ratios, trace element ratios (Mg Ca and Sr Ca), and growth rate. Throughout the entire speleothem record, δ18O variability is related to changes in effective recharge. This is supported by the pattern of changes in δ13C, Mg Ca and growth rate. The 8.2 ka event is marked as a centennial-scale negative excursion in El Soplao δ18O, starting at 8.19 ± 0.06 ka and lasting until 8.05 ± 0.05 ka, suggesting increased recharge at the time. Although this is supported by the other proxies, the amplitude of the changes is minor and largely within the realm of variability over the preceding 1000 years. Further, the shift to lower δ18O leads the other proxies, which we interpret as the imprint of the change in the isotopic composition of the moisture source, associated with the meltwater flux to the North Atlantic. A comparison with other well-dated records from south-western Europe reveals that the timing of the 8.2 ka event was synchronous, with an error-weighted mean age for the onset of 8.23 ± 0.03 and 8.10 ± 0.05 ka for the end of the event. This compares favourably with the North Greenland Ice Core Project (NGRIP) record. The comparison also reveals that the El Soplao δ18O is structurally similar to the other archives in south-western Europe and the NGRIP ice-core record.
Comparación del clima interglacial eemiense y holoceno en el norte de España a partir de los indicadores paleoclimáticos de estalagmitas de la Cueva del Cobre (Palencia)
(Geotemas, 2008) Muñoz García, María Belén; Martín Chivelet, Javier; Rossi Nieto, Carlos; Ford, D.C.; Schwarez, H.P.
El Eemiense se suele considerar un buen análogo del Holoceno a pesar de la diferente configuración orbital de cada época. La comparación de varios indicadores paleoclimáticos obtenidos en estalagmitas eemienses y holocenas de la Cueva del Cobre (Montaña Palentina) aporta datos que permiten verificar esta supuesta similitud. Los indicadores paleoclimáticos comparados son la tasa de crecimiento de las estalagmitas, las texturas de la calcita y los isótopos estables de oxígeno. En comparación con los holocenos, los espeleotemas eemienses son más grandes porque han crecido sin interrupción durante más tiempo, presentan una variedad menor de texturas de calcita y apenas registran láminas anuales. Además, ni las texturas de calcita ni la composición isotópica de oxígeno muestran signos de alteración diagenética. En función de estos indicadores se ha podido deducir que el clima de la zona de estudio fue durante el Eemiense ligeramente más cálido que durante el Holoceno y considerablemente más seco, contradiciendo las estimaciones más aceptadas del clima global para el Último Periodo Interglacial. El clima eemiense en la zona de estudio fue además más estable y tuvo una estacionalidad menos marcada que en los últimos 6000 años. El análisis de los cambios sincrónicos de estos indicadores ha permitido estimar una duración del Último Periodo Interglacial de ~21ka en esta zona.
Chronology of Termination II and the Last Interglacial Period in North Spain based on stable isotope records of stalagmites from Cueva del Cobre (Palencia)
(Journal of iberian geology, 2007) Muñoz García, María Belén; Martín Chivelet, Javier; Rossi Nieto, Carlos; Ford, D.C.; Schwarcz, H.P.
New insight into the timing and structure of the Last Interglacial Period (Eemian) was obtained through U-Th dating of four speleothems from Northern Spain and an analysis of their stable isotope records. The four stalagmites examined were collected from different levels of Cueva del Cobre, a cold high-mountain cave in the Cantabrian Ranges (N Spain), in which speleothem growth took place essentially during the warmer interestadials. Through 18 TIMS and ICPMS datings and 263 stable isotope analyses, the onset of the Eemian interglacial period was precisely dated at 150±2 ka, an age consistent with a few other palaeoclimatic records but notably younger than the age ascribed by the Milankovitch theory. We also date the Eemian–Weichselian transition (~115 ka)for the first time in the Iberian Peninsula. U-Th ages revealed a consistent anomaly at ~105-100 ka BP, which could be related to a drastic environmental change during the MIS-5c interestadial. This event would have caused the resetting of the U-Th system at the base of the stalagmites during a short time interval. In addition, we propose a new simple geochemical test to ensure the lack of disturbance of this type of samples for dating purposes.
Quartz Cementation in Cretaceous and Jurassic Reservoir Sandstones from the Salam Oil Field, Western Desert, Egypt: Constraints on Temperature and Timing of Formation from Fluid Inclusions
(Quartz Cementation in Sandstones : Special Publication 29 of the IAS, 2009) Marfil Pérez, Rafaela; Rossi Nieto, Carlos; Lozano, R. P.; Permanyer, A.; Ramseyer, K.; Worden, Richard H.; Morad, Sadoon
Middle Jurassic and Lower Cretaceous reservoir sandstones in the Salam oil field (in Egypt's Western Desert), are mostly quartz-arenites with abundant quartz overgrowths. Most overgrowths precipitated relatively early in the diagenetic history, only pre-dated by mechanical- and minor chemical compaction. Integration of the diagenetic sequence with the geological and maturation history of the basin, indicates that quartz cementation occurred prior to oil filling the reservoirs during the Eocene, probably during the Late Cretaceous, related to high subsidence and heating rates. Homogenization temperatures (Th) of aqueous fluid inclusions that occur along the boundary between the detrital quartz grains and their overgrowths indicate that the quartz cements started to grow at temperatures from about 116°C to 135°C. These palaeotemperatures are similar to, or slightly higher than, present-day formation temperatures, and show a positive correlation with present depth of burial. The palaeotemperatures obtained from fluid inclusions are higher than predicted from thermal history models. There are several possible explanations for these relatively high palaeotemperatures: (i) the Late Cretaceous burial depths were higher than initially presumed; (ii) the Late Cretaceous palaeogeothermal gradients were considerably higher than present gradients; (iii) migrating hot fluids were responsible for the growth of quartz cements, at temperatures above those resulting from the contemporary conductive geothermal gradient; or (iv) fluid inclusions were trapped at lower temperatures and re-equilibrated during subsequent burial. Although thermal re-equilibration of the grain-boundary fluid inclusions is hypothetically possible, and would resolve the inconsistencies between Th data and the thermal and migration histories, there is no clear evidence supporting re-equilibration, given the narrow ranges of Th in each sample and the lack of a correlation between Th and parameters such as inclusion salinity or size.
Replication and reinsertion of stalagmites sampled for paleoclimatic purposes
(International Journal of Speleology, 2018) Baeza, Eleuterio; Lozano, Rafael P.; Rossi Nieto, Carlos
Sampling stalagmites for paleoclimatic study can enter into conflict with preserving the beauty and integrity of caves. To minimize this impact, a variety of sampling strategies have been used by researches aware of cave-conservation issues. Based on our experience in two caves (El Soplao and La Buenita, Cantabria, N Spain), we propose to apply molding and casting laboratory techniques to create replicas of stalagmites, placing the replicas back in the original cave locations so that the impact of sampling to the cave is severely reduced. We provide detailed descriptions of the molding and casting methods, which vary depending on stalagmite size. For relatively small specimens (less than ~35 cm tall), we use a single-piece mold and two jackets. For larger stalagmites (~40-70 cm tall), we use a two-piece mold and two jackets. In a first casting step, we obtain a master piece in dental plaster that is preserved. In a subsequent casting step, we use epoxy resin to generate the replica that will be placed in the cave. We use extra-hard plaster coated with epoxy resin to fix the replicas to their original substrates. Both the epoxy resin and plaster are carefully dyed to match the original surface texture and color of the sampled stalagmites. Once in place, the stalagmite replicas are almost indistinguishable from the natural specimens.
Limited thermochemical sulfate reduction in hot, anhydritic, sour gas carbonate reservoirs: The Upper Jurassic Arab Formation, United Arab Emirates
(Marine and Petroleum Geology, 2019) Morad, Daniel; Nader, Fadi H.; Morad, Sadoon; Rossi Nieto, Carlos; Gasparrini, Marta; Alsuwaidi, Mohammad; Al Darmaki, Fatima; Hellevang, Helge
Limited thermochemical sulfate reduction (TSR) in hot (130–160°C) and anhydrite-rich sour gas reservoir carbonates of the Arab Formation (Upper Jurassic) is manifested by rare calcitization of anhydrite with slightly lower δ13CVPDB values (−3.2 to −0.1‰) than calcite precipitated in equilibrium with Late Jurassic seawater. Fluid inclusion microthermometry of calcite that has replaced anhydrite indicates that TSR occurred between 130°C and 160°C. The lack of evidence for extensive TSR, despite the suitable current temperatures and abundant sulfates in the gas reservoir, coupled with the relatively more common TSR-related calcite in the flanks (water zone) than crest (gas zone), indicate that: (1) gas emplacement while the reservoir was buried at shallower depth slowed down or inhibited TSR in the crest even when it subsequently reached depths where extensive TSR would occur, and (2) H2S (up to 38 vol%) has migrated from the underlying Permo-Triassic and/or Jurassic sulfate-carbonate deposits. This study demonstrates that constraining the timing of hydrocarbon emplacement within the context of burial-thermal history is crucial for a better understanding of the origin and distribution of H2S in hot, anhydrite-rich, sour gas reservoirs.
Diagenesis, provenance and reservoir quality of Triassic TAGI sandstones from Ourhoud field, Berkine (Ghadames) Basin, Algeria
(Marine and Petroleum Geology, 2002) Rossi Nieto, Carlos; Kälin, Otto; Arribas Mocoroa, José; Tortosa, A.
The Triassic TAGI (Trias Argilo-Gréseux Inférieur) fluvial sandstones are the main oil reservoirs in the Berkine Basin, Algeria. Nonetheless, their provenance and diagenesis, and their impact on reservoir quality, are virtually unknown. Samples from the Ourhoud field, representing the Lower, Middle and Upper TAGI subunits, were studied using a combination of petrographic, mineralogical and geochemical techniques. The Lower TAGI sandstones have an average framework composition of Q98.3F0.6R1.1 and 95% of the quartz grains are monocrystalline. By contrast, the Middle–Upper TAGI sandstones have an average framework composition of Q88.3F9.8R1.9 and 79.7% of the quartz grains are monocrystalline. The Lower TAGI quartz arenites derived from Paleozoic siliciclastic rocks, whereas the Middle–Upper TAGI subarkoses originated mainly from metamorphic terrains. This change in provenance is a potential criterion for correlation within the TAGI. Also, this change has contributed to the significantly different diagenetic paths followed by the Lower TAGI quartz arenites and the Middle–Upper TAGI subarkoses. Grain-coating illitic clays are abundant in the Lower TAGI, where they exert a critical control on reservoir quality. These clays are interpreted as pedogenic and/or infiltrated in origin and to have had, in part, smectitic precursors. Shallow burial Fe-dolomite cementation was favored in the downthrown block of the field-bounding fault, where it contributed to the poor reservoir quality. Magnesite–siderite cements are multiphase. The earliest generation is composed of Fe-rich magnesite that precipitated during shallow burial from hypersaline fluids with high Mg/Ca ratios, probably refluxed residual brines associated with the Liassic evaporites. Later magnesite–siderite generations precipitated during deeper burial from waters with progressively higher Fe/Mg ratios. Authigenic vermicular kaolin largely consists of dickite that replaced previously formed kaolinite. Dickitization was followed by late-stage illitization related to the dissolution of detrital and authigenic K-feldspar. Quartz, the most abundant cement, was mainly sourced by the pressure- or clay-induced dissolution of detrital quartz and is a critical factor controlling the reservoir quality. Overall, quartz cement is more abundant in the Lower TAGI than in the Middle–Upper TAGI, and this increase correlates with a decrease in average porosity. Within the Lower TAGI, quartz cement abundance is stratigraphically very variable, which is in part related to facies controlled variations in grain-coating clay, resulting in major vertical variations in reservoir quality. Anhydrite and barite cements postdate quartz overgrowth. The sulfate necessary for their formation was likely sourced by deep subsurface dissolution of Late Triassic–Liassic evaporites.