Person:
Rodríguez Berriguete, Álvaro

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First Name
Álvaro
Last Name
Rodríguez Berriguete
URI
https://hdl.handle.net/20.500.14352/80835
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Mineralogía y Petrología
Area
Petrología y Geoquímica
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2019 - 201912020 - 20221
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Item Type: Publication × Subject: 552.545(460.413) ×

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    Carbonate tufas as archives of climate and sedimentary dynamic in volcanic settings, examples from Gran Canaria (Spain)
    (Sedimentology, 2022) Rodríguez Berriguete, Álvaro; Camuera, Jon; Alonso Zarza, Ana María
    Three Holocene tufas from Gran Canaria volcanic island were studied with the aim of deciphering their sedimentary evolution through space and time. Las Temisas tufa (south-eastern arid part of the island) is dominantly composed of oncoids, intraclasts, phytoclasts, coated stems, minor thin stromatolites, and a high amount of siliciclastics. It was deposited in a fluvial system with variable flow velocities and palustrine conditions areas, which alternated with high energy events. Azuaje tufa (northern humid part of the island) is composed of coated stems, stromatolites, oncoids and phytoclasts, with relatively low amounts of siliciclastics, suggesting slow-flowing and palustrine conditions and a relatively low incidence of (high energy) floodings. Los Berrazales tufa (north-west of Gran Ganaria, the most humid one), is mainly composed of coated stems and crystalline crusts, formed in a laminar flow regime. Dominant clastic sedimentation in Las Temisas and high calcite growth rates in Los Berrazales led to a poor development of stromatolites in comparison with Azuaje. Las Temisas and Azuaje deposits have similar upward evolution with decreasing trend in siliciclastics and increasing trend in carbonates. However, Las Temisas has higher siliciclastic and lower phytoclastic contents suggesting a less vegetated area and more arid climate than in the other deposits. Additionally, tufas record local events common in volcanic terrains. Azuaje presents three units bounded by erosive discontinuities, which reveal significant erosion by enhanced runoff that could be caused by loss of vegetation due to wildfires related to volcanic eruptions at headwaters. Las Temisas record a possible interruption in sedimentation represented by aligned boulders due to rockfalls from the hillsides. These deposits formed from waters with similar chemistry providing to the carbonates their similar signals in δ13C–δ18O stable isotopes and 87Sr/86Sr ratios like that of the volcanic rocks. This work shows how, in volcanic areas, tufas are unique archives of the climate, vegetation and volcanic-related processes, because all imprint the sedimentary regime of tufa deposition.
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    Controlling factors and implications for travertine and tufa deposition in a volcanic setting
    (Sedimentary Geology, 2019) Rodríguez Berriguete, Álvaro; Alonso Zarza, Ana María
    This work studies a fossil system of perched and fluvial travertines passing distally to fluvial tufas within a volcanic ravine. Sedimentology, petrology and geochemistry of fossil aragonitic-calcitic travertines and downstream calcitic tufas from the Azuaje volcanic ravine were studied. These spring-related carbonates seem to be formed after the Mid-Holocene climate change, the transition from a monsoon-dominated humid climate to an arid-semiarid climate controlled by trade winds. The main travertine facies include rafts, dendrites/shrubs, ooids, oncoids and stromatolites among others, whereas tufas are characterised by phytoclasts, oncoids, coated stems, intraclasts and stromatolites. Facies observed can be (i) microbial-influenced when the microbial growth rate is greater than the precipitation rate and flow energy is not above the threshold value tolerated by microbes, or (ii) inorganic-dominated if the precipitation rate exceeds that of the microbial growth rate and/or flow energy is above the threshold tolerated by microbes. Travertine facies vary from mostly inorganic to microbially-dominated, whereas tufa facies are mostly microbially-influenced. Observed changes of facies in both travertines and tufas were interpreted as due to changes in environmental conditions from (a) less to more evaporative, (b) less saturated to oversaturated, and (c) high to low energy. Changes in textures, mineralogy, geochemistry and stable isotope composition downstream from travertine to tufa suggest a decrease in the CaCO3 precipitation rate and an increase in microbial influence from travertines (proximal part of the system) to (distal) tufas. Our study case illustrates the wide variety of facies and processes operating in spring-related travertine and tufa deposits. The details of arrangement, mineralogy, facies and geochemistry of the deposits were mostly controlled by climate and hydrogeology, although the volcanic setting, provided suitable conditions for spring‑carbonate deposition.