Person:
González Acebrón, Laura

First Name

Laura

Last Name

González Acebrón

URI

https://hdl.handle.net/20.500.14352/75257

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Geológicas

Department

Geodinámica, Estratigrafía y Paleontología

Area

Estratigrafía

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Now showing 1 - 10 of 37

Sand provenance and implications for paleodrainage in a rifted basin: the Tera Group (N. Spain)
(Journal of iberian geology, 2010) González Acebrón, Laura; Arribas Mocoroa, José; Mas Mayoral, José Ramón
Fluvial-fan and fluvial siliciclastic strata, developed during the rifting that generated the Cameros Basin (North Spain), record important provenance changes that reveal source areas compositions and locations, paleodrainage evolution and rift patterns. The Tera Group represents the first rifting stage in the Cameros Basin, containing fluvial-fan sediments at the lower part of the sedimentary fill that evolve to fluvial and lacustrine systems in the upper part of the record. Our quantitative sandstone petrographic analysis evidences the presence of three main petrofacies related closely to the rift basin evolution. At the base of the sedimentary succession, Petrofacies 1 (quartzolithic) indicates that the fluvial-fans source areas included Jurassic marine carbonates and older siliciclastic Mesozoic units, as well as metamorphic supplies from the West Asturian Leonese Zone (WALZ). Variscan basement sources of this metamorphic area (WALZ) were more abundant in the upper fluvial record (Petrofacies 2, quartzofeldspathic). Further, the influence of plutonic source areas with a mixed potassic and calcium-sodium composition is also recorded, probably related to the Central Iberian Zone (CIZ). In addition, a local sedimentary input was active during the fluvial riftand lacustrine stages (Petrofacies 2 and 3, both quartzofeldspathic), as a function of the palaeogeographical position of the Jurassic marine rocks and the level of erosion reached. Plutonic rock fragments have not been observed in the Tera Group sandstones of the western part of the basin. Thus, deeper erosion of the basement in the eastern Cameros Basin is suggested. The provenance evolution from quartzolithic to quartzofeldspathic petrofacies registered in Tera Group siliciclastic deposits is due to the higher influence of transversal supplies during the fluvial-fan stage (quartzolithic) to more important axial inputs during the fluvial stage (quartzofeldspathic). This provenance change represents the evolution from an undissected rift shoulder stage to more advanced stages of rifting (dissected rift shoulder) and during the beginning of a provenance cycle in a rifted basin. [RESUMEN] Los sedimentos de abanicos fluviales y fluviales propiamente dichos desarrollados durante el proceso de rift que generó la Cuenca de Cameros (Norte de España) registraron importantes cambios de procedencia que proporcionan información sobre la composición y localización de sus áreas fuente, la evolución del paleodrenaje y los patrones de rift. Este estudio se centra en el Grupo Tera (Tithoniense) en el sector oriental de la Cuenca de Cameros. El Grupo Tera representa el primer estadio de rift en dicha cuenca, y está constituido por sedimentos de abanicos fluviales en la parte inferior del relleno sedimentario, que evolucionan a sistemas fluviales y lacustres hacia la parte superior del registro. El estudio petrográfico cuantitativo de las areniscas indica la presencia de tres petrofacies principales que muestran una estrecha relación con la evolución del rift. En la base del registro sedimentario, la Petrofacies 1 (cuarzolítica) manifiesta que las áreas fuente de los abanicos fluviales incluyen tanto carbonatos Jurásicos marinos como unidades siliciclásticas mesozoicas previas, así como influencias metamórficas de la Zona Asturoccidental Leonesa (WALZ). Los aportes del basamento varisco procedentes de esta área fuente metamórfica (WALZ) fueron más importantes en la parte alta del registro (Petrofacies 2, cuarzofeldespática). Además, se detecta la influencia de áreas fuente plutónicas con una composición mixta (potásica y calcosódica), probablemente relacionadas con la Zona Centroibérica (CIZ). También existió un aporte sedimentario local durante los estadios fluviales y lacustres (Petrofacies 2 y 3, ambas cuarzofeldespáticas), que tuvo lugar en función de la posición paleogeográfica de las rocas marinas Jurásicas y del nivel de erosión alcanzado. Si comparamos los dos sectores de la cuenca, los fragmentos de roca plutónica no han sido observados en las areniscas del Grupo Tera en el sector occidental de la cuenca. Por lo tanto, se deduce un nivel de erosión del basamento más profundo en el sector occidental. La evolución de la procedencia desde petrofacies cuarzolíticas a petrofacies cuarzofeldespáticas registrada en los depósitos siliciclásticos del Grupo Tera se debe a una mayor influencia de los aportes transversales durante la sedimentación de los abanicos fluviales (cuarzolíticos) hacia una mayor influencia de aportes axiales durante la etapa fluvial (cuarzofeldespática). Esta variación en la procedencia representa la evolución desde un estadio de hombrera de rift no erosionada a estadios más avanzados del rifting (hombrera de rift erosionada) y el comienzo de un ciclo de procedencia en una cuenca de rift.
REPLY: Answer to the comment of Casas et al. about González Acebrón et al.’s (2011) paper
(International journal of earth sciences, 2012) González Acebrón, Laura; Goldstein, R.H.; Mas Mayoral, José Ramón; Arribas Mocoroa, José
Submarine metalliferous carbonate mounds in the Cambrian of the Baltoscandian Basin induced by vent networks and water column stratification
(Scientific reports, 2022) Álvaro, J.J.; Holmer, Lars E.; Shen, Yanan; Popov, Leonid E.; Pour, Mansoureh Ghobadi; Zhang, Zhifei; Zhang, Zhiliang; Ahlberg, Per; Bauert, Heikki; González Acebrón, Laura
Two massive precipitation events of polymetallic ore deposits, encrusted by a mixture of authigenic carbonates, are documented from the Cambrian of the semi-enclosed Baltoscandian Basin. δ34S (‒9.33 to ‒2.08‰) and δ33S (‒4.75 to ‒1.06‰) values from the basal sulphide breccias, sourced from contemporaneous Pb–Zn–Fe-bearing vein stockworks, reflect sulphide derived from both microbial and abiotic sulphate reduction. Submarine metalliferous deposits were triggered by non-buoyant hydrothermal plumes: plumes of buoyant fluid were trapped by water column stratification because their buoyancy with respect to the environment reversed, fluids became heavier than their surroundings and gravitational forces brought them to a halt, spreading out laterally from originating vents and resulting in the lateral dispersion of effluents and sulphide particle settling. Subsequently, polymetallic exhalites were sealed by carbonate crusts displaying three generations of ikaite-to-aragonite palisade crystals, now recrystallized to calcite and subsidiary vaterite. Th of fluid inclusions in early calcite crystals, ranging from 65 to 78 ºC, provide minimum entrapment temperatures for carbonate precipitation and early recrystallization. δ13Ccarb (‒1.1 to + 1.6‰) and δ18Ocarb (‒7.6 to ‒6.5‰) values are higher than those preserved in contemporaneous glendonite concretions (‒8.5 to ‒4.7‰ and ‒12.4 to ‒9.1‰, respectively) embedded in kerogenous shales, the latter related to thermal degradation of organic matter. Hydrothermal discharges graded from highly reduced, acidic, metalliferous, and hot (~ 150 ºC) to slightly alkaline, calcium-rich and warm (< 100 ºC), controlling the precipitation of authigenic carbonates.
Fluid migration recorded by fluid inclusions in crack-sealed quartz veins and sandstone host rock; Cameros Basin, Spain
(Journal of iberian geology, 2021) González Acebrón, Laura; López Elorza, Maialen; Mas Mayoral, José Ramón; Arribas Mocoroa, José; Omodeo-Salé, Silvia
The role of deep hydrothermal fluid circulation through fractures and their impact on the sandstone host rock is studied in an extensional sedimentary basin (Cameros Basin, Spain) affected by a post-extensional hydrothermal metamorphism. The quartzarenites of the Urbión Group constituted a hydrocarbon carrier affected by very low to low-grade hydrothermal metamorphism during Late Albian to Coniacian. This process generated abundant quartz veins and transformed the quartzarenites into quartzites. This study compares the microthermometry of the fluid inclusion asemblages (FIAs) in the veins and in the quartz grain overgrowths in the quartzites, in order to understand the behavior of the hydrothermal fluids through fractures and their effects in the host rock. Fluid inclusions in the quartz grain overgrowths contain liquid and vapor at room temperature and homogenize to the liquid (Th: 124–265 °C, H2O + NaCl system). Those of quartz veins present both liquid and vapor CO2 and an aqueous liquid phase (room temperature). Final homogenization is to the liquid (Th: 109–282 °C, H2O + NaCl + CO2, mean values of amount-of-substance fractions: 0.92, 0.01, 0.07). Large Th variation within each FIA is common, due to crack and sealing processes and to reequilibration by successive thermal pulses. In contrast, the narrow Th range in each FIA towards the top of the record indicates that these inclusions are probably not reequilibrated. Two growing stages are recognized under SEM-CL in the quartz grain overgrowths, one diagenetic and another hydrothermal, the later with FIAs showing Th similar than the veins. The results can help in the evaluation of the geo-energy resources in sedimentary basins.
Sandstone petrofacies in the northwestern sector of the Iberian Basin
(Journal of iberian geology, 2007) Arribas Mocoroa, José; Ochoa, M.; Mas Mayoral, José Ramón; Arribas Mocoroa, María Eugenia; González Acebrón, Laura
During the most active rifting stages in the northwestern sector of the Iberian Basin (Cameros Basin and Aragonese Branch of the Iberian Range), thick sequences of continental clastic deposits were generated. Sandstone records from Rift cycle 1 (Permo-Triassic) and Rift cycle 2 (Late Jurassic-Early Cretaceous) show similarities in composition. Based on the most recent data, this paper describes sandstone petrofacies developed during both rifting periods. Six petrofacies can be distinguished: two associated with Rift cycle 1 (PT-1 and PT-2) and four with Rift cycle 2 (JC-1 to JC-4). All six petrofacies can be classifi ed as sedimentoclastic or plutoniclastic. Sedimentoclastic petrofacies developed during early rifting stages either through the recycling of pre-rift sediments or signifi - cant palaeogeographical changes. These facies comprise a thin succession (<100 m) of clastic deposits with mature quartzose and quartzolithic sandstones containing sedimentary and metasedimentary rock fragments. Carbonate diagenesis is more common than clay mineral diagenesis. Sedimentoclastic petrofacies have been identifi ed in Rift cycle 1 (Saxonian facies, PT-1) and Rift cycle 2 (JC-1 and JC-3; Tithonian and Valanginian, respectively). In the absence of the pre-rift sedimentary cover, metasedimentoclastic petrofacies sometimes develop as a product of the erosion of the low- to medium-grade metamorphic substratum (Petrofacies JC-2, Tithonian-Berriasian). Plutoniclastic petrofacies were generated during periods of high tectonic activity and accompanied by substantial denudation and the erosion of plutonites. Forming thick stratigraphic successions (1000 to 4000 m), these feldspar-rich petrofacies show a rigid framework and clay mineral diagenesis. In Rift cycle 1, plutoniclastic petrofacies (PT-2) are associated with the Buntsandstein. This type of petrofacies also developed in Rift cycle 2 in the Cameros Basin (JC-4) from DS-5 to DS-8 (Hauterivian-Early Albian), and represents the main basin fi ll interval. Sedimentoclastic and plutoniclastic petrofacies can be grouped into three pairs of basic petrofacies. Each pair represents a ‘provenance cycle’ that records a complete clastic cycle within a rifting period. Petrofacies PT-1 and PT-2 represent the ‘provenance cycle’ during Rift-1. In the Cameros Basin, two provenance cycles may be discerned during Rift cycle 2, related both to the Tithonian-Berriasian and the Valanginian-Early Albian megasequences. Tectonics is the main factor controlling petrofacies. Other factors (e.g., maturation during transport, local supply) may modulate the compositional signatures of the petrofacies yet their main character persists and even outlines the hierarchy of the main bounding surfaces between depositional sequences in the intracontinental Iberian Rift Basin.
Evolution of an intra-plate rift basin: the Latest Jurassic-Early Cretaceous Cameros Basin (Northwest Iberian Ranges, North Spain)
(Geo-guías, Post-Meeting Field trips 28th IAS Meeting, Zaragoza, 2011) Mas Mayoral, José Ramón; Benito Moreno, María Isabel; Arribas Mocoroa, José; Alonso Millán, Ángela; Arribas Mocoroa, María Eugenia; Lohmann, K.C.; González Acebrón, Laura; Hernán, J.; Quijada, Isabel Emma; Suárez González, Pablo; Omodeo Salé, S.; Arenas, Concha; Pomar, Luis; Colombo, Ferrán
Multiphase quartz cementation in sandstones: Terra group (Tithonian, Cameros basin, NE Spain)
(25rd IAS Meeting of Sedimentology : Grece, Patras, 4-7 September 2007, Meeting of Sedimentology. Book and abstracts, 2007) González Acebrón, Laura; Mas Mayoral, José Ramón; Arribas Mocoroa, José; Goldstein, Robert H.; Benito Moreno, María Isabel
Role of sandstone provenance in the diagenetic albitization of feldspars A case study of the Jurassic Tera Group sandstones (Cameros Basin, NE Spain)
(Sedimentary Geology, 2011) González Acebrón, Laura; Arribas Mocoroa, José; Mas Mayoral, José Ramón
The Cameros Basin (Iberian Chain, NE Spain) formed during the latest Jurassic–Early Cretaceous rifting stage in an extensional regime characterized by high subsidence rates. Its sedimentary infill (thicker than 6000 m) has been subdivided into eight depositional sequences (DS) mainly composed of continental sediments. DS 1 and DS 2 represent the first rifting stage (Tera Group, Tithonian), mainly formed by fluvial and lacustrine sediments. Sandstone petrofacies evolved from quartz-sedimentolithic in DS 1 to quartz-feldspathic in DS 2 due to the rifting process. In DS 2, three different types of detrital feldspars (K-feldspars, albites and polysynthetic plagioclases) with similar sodium-rich compositions (mean: Ab94.0 An4.5 Or1.5) can be recognized. Chemically pure nonluminescent albites (AbN99%) are common. In DS 2, diagenetic albitization of both plagioclases and K-feldspars is inferred from conventional microscopy observations, cathodoluminescence and electron microprobe analyses. DS 1 contains few plagioclase grains, which showno evidence of transformation into albite.Although the albitization is characterized as diagenetic it seems to be provenance-controlled since it affects the units showing higher original plagioclase/Kfeldspar ratio (DS 2), due to the greater influence of plutonic and metamorphic source areas in DS 2. Possible Na sources are: (1) the percolation ofmoderate to high salinity residual brines fromrelated alkaline lakes developed at top of DS 2 in the eastern sector of the basin, (2) clay mineral reactions (sodium smectite to illite and chlorite) indicated by mudstone composition in the interlayered mudstones, and (3) the replacement of detrital sodium plagioclases by carbonate. These three sources can be complementary.
Fluid-inclusion petrography in calcite stalagmites: Implications for entrapment processes
(Journal of sedimentary research, 2021) López Elorza, Maialen; Muñoz García, María Belén; González Acebrón, Laura; Martín Chivelet, Javier
Fluids trapped in speleothems have an enormous potential in frontier fields of paleoclimate and paleohydrological research. This potential is, however, hampered by diverse scientific and technical limitations, among which the lack of a systematic methodology for genetically characterizing fluid inclusions is a major one, as these can have different origins, and thus, the trapped fluid (usually water), different meanings. In this work, we propose a systematic petrological classification of fluid inclusions, based on: 1) the temporal relation between fluid inclusions and the host calcite, 2) the spatial relation between fluid inclusions and the “crystallites” and crystals aggregates, and 3) the phases (water, air) trapped inside fluid inclusions. The first criterion allows dividing fluid inclusions in two main categories: primary and secondary, whose identification is critical in any research based on trapped fluids. The other two criteria allow the definition of eight types of primary and four types of secondary fluid inclusions. Primary fluid inclusions contain the drip water that fed stalagmites at the time of crystal growth, and can be intercrystalline, i.e., located between adjacent crystallites, or intracrystalline, i.e., with the fluid trapped within crystallites. We differentiate six main types among the intercrystalline fluid inclusions (elongate, thorn-shaped, down-arrow, interbranch, macro-elongate, and bucket) and other two among intracrystalline inclusions (pyriform and boudin). In primary inclusions, water is the main phase, while gas is much less abundant. The presence of gas could be related to slow drip rates or degassing in the cave, but also to later leakage due to changes in temperature and humidity often occurring during inadequate handling of speleothem samples. Secondary fluid inclusions were clearly related to younger water inlet through stratigraphic disruptions or unconformities. They are formed after water infiltration, but sealed before the renewed crystal growth. We differentiate four main types of secondary inclusions: interconnected, rounded, triangular, and vertical fluid inclusions. The identification of primary and secondary fluid inclusions in speleothems is a key for interpretation in paleoclimate studies. Integration of petrological results allow establishment of three different genetic scenarios for the formation of fluid inclusions, whose identification can be relevant because of their predictive character.
Easily altered minerals and reequilibrated fluid inclusions provide extensive records of fluid and thermal history: gypsum pseudomorphs of the Tera Group, Tithonian-Berriasian, Cameros Basin
(Central European Journal of Geosciences, 2012) González Acebrón, Laura; Goldstein, Robert H.; Arribas Mocoroa, José
This study reports a complex fluid and thermal history using petrography, electron microprobe, isotopic analysisand fluid inclusions in replacement minerals within gypsum pseudomorphs in Tithonian-Berriasian lacustrine de-posits in Northern Spain. Limestones and dolostones, formed in the alkaline lakes, contain lenticularly shapedgypsum pseudomorphs, considered to form in an evaporative lake. The gypsum was replaced by quartz andnon-ferroan calcite (Ca-2), which partially replaces the quartz. Quartz contains solid inclusions of a preexistingnon-ferroan calcite (Ca-1), anhydrite and celestine.High homogenization temperatures (Th) values and inconsistent thermometric behaviour within secondary fluidinclusion assemblages in quartz (147-351◦C) and calcite (108-352◦C) indicate high temperatures after precipita-tion and entrapment of lower temperature FIAs. Th are in the same range as other reequilibrated fluid inclusionsfrom quartz veins in the same area that are related to Cretaceous hydrothermalism.Gypsum was replaced by anhydrite, likely during early burial. Later, anhydrite was partially replaced by Ca-1associated with intermediate burial temperatures. Afterward, both anhydrite and Ca-1 were partially replacedby quartz and this by Ca-2. All were affected during higher temperature hydrothermalism and a CO2-H2O fluid.Progressive heating and hydrothermal pulses, involving a CO2-H2O fluid, produce the reequilibration of the FIAs,which was followed by uplift and cooling