"The book aims at describing to a broad audience 50 years of research of Charles Darwin Foundation as part of the worldwide efforts in conservation science. A model case is presented showing how ...interdisciplinary work across a broad range of scientific disciplines (evolution science, taxonomy, botany, terrestrial and marine ecology, ecological restoration, fisheries science, oceanography, social and economic science) has contributed to the conservation and sustainable development of the Galapagos archipelago and to the advancement of science. The book describes the state-of-the-art knowledge on the Galapagos socio-ecosystem, presents modern modeling tools for the integration of information from diverse science disciplines and highlights contrasting viewpoints with regard to future scenarios for reconciling conservation with socio-economic development of the archipelago. The book is innovative in its multidisciplinary focus on conservation and in presenting up- to-date tools for scenario modeling. The book is structured into the following four chapters: The evolutionary context; biodiversity assessment and monitoring of change; a systemic approach: modeling and restoration; reconciliation of conservation with socio-economic development. Each chapter is comprised of several individual papers and ends with a chapter summary that highlights the main findings and conclusions. The book integrates the knowledge and reflections of 30 scientists, of which many have dedicated a substantial part of their professional life to the Galapagos archipelago, to the conservation of its biodiversity and to the sustainable management of its resources. The book can be considered a milestone on the way to the successful conservation and sustainable development of this unique world heritage"--
•δ56Fe heterogeneity is observed in plume-influenced basalts from the GSC.•The δ56Fe composition of these basalts cannot result from melting of a peridotite.•Lithological heterogeneity in the ...Galápagos mantle plume is required.•δ56Fe heterogeneity of oceanic basalts results from lithological heterogeneity.
The extent of lithological heterogeneity in the Earth's convecting mantle is highly debated. Whilst the presence of pyroxenite in the mantle source regions of Ocean Island Basalts (OIBs) has traditionally been constrained using the minor-element chemistry of olivine phenocrysts, recent studies have shown that the Ni and Mn contents of primitive olivines are influenced by the conditions of mantle melting, as well as magma chamber processes. Nevertheless, constraining the lithological properties of the mantle is important due to its influence on the P-T path followed by solid mantle material during adiabatic ascent, as well as the density of upwelling mantle plumes. We have therefore explored the use of Fe-isotopes as a novel method of tracing lithological heterogeneity in the mantle source regions beneath plume-influenced segments of the global Mid-Ocean Ridge system as well as OIBs.
We present new Fe-isotope (δ56Fe) and trace-element data for 26 basaltic glasses from the plume-influenced Galápagos Spreading Centre to investigate the relative roles of pyroxenite and peridotite in the mantle source region of oceanic basalts. Our data reveals significant heterogeneity in the Fe-isotope composition of the Galápagos Spreading Centre basalts (+0.05 to +0.25‰ δ56Fe), which correlates with key major- and trace-element parameters (e.g. CaO(8)/Al2O3(8), La/Smn). Application of new models developed to calculate Fe-isotope fractionation during mantle melting, alongside Monte Carlo simulations for melting of a 2-component peridotite mantle, show that this variation cannot be caused by changes in melting processes and/or oxygen fugacity of a peridotitic mantle. Instead, our new δ56Fe data is best explained by variations in the proportion of isotopically-heavy pyroxenite-derived melt that contributes to the GSC basalts, and conclusively shows that lithological heterogeneity exists in the Galápagos mantle plume. Our findings have implications for the moderately-heavy δ56Fe compositions measured in plume-influenced basalts from the Society Islands, Rochambeau Ridges of the Lau back-arc basin, and the FAMOUS segment of the Mid-Atlantic Ridge, which we suggest may also represent contribution from pyroxenite-derived melts.
The Galápagos are home to a wide-ranging assortment of unusual plants and animals. The islands became famous as the site of Charles Darwin's research leading to his theory of evolution by natural ...selection, and their magnificent flora and fauna continue to draw visitors from around the world. Based on the author's 16 years of fieldwork and featuring his exceptional photography, Flowering Plants of the Galápagos is the first accessible, in-depth yet compact guide to the plant life of the area. An invaluable resource for tourists, natural history enthusiasts, and professionals, the book: • Introduces the botanical history of the islands and their varied ecological zones • Allows easy identification of 436 flowering plants (77 families, 192 genera, and 390 species) • Covers endemic plants found exclusively on the islands; native plants, which grow on the Galápagos and elsewhere; and exotic plants present as a result of human actions • Offers thorough accounts of the plants which give the scientific, common, and family names; range; islands inhabited; habitat; description; and additional notes of interest • Is richly illustrated with 266 color photographs of flowering plants and 117 of plant pollinators, vegetation zones, non-flowering plants, and the islands themselves • Organizes species by form, leaf arrangement, and flower color and includes descriptive plant drawings to aid in identification • Provides a map of the Galápagos and a list of plants likely to be seen at popular tourist sites
An energetic eruption started on 25 May 2015 from a circumferential fissure at the summit of Wolf volcano on Isabela Island, western Galápagos. Further eruptive activity within the Wolf caldera ...followed in mid‐June 2015. As no geodetic observations of earlier eruptions at Wolf exist, this eruption provides an opportunity to study the volcano's magmatic plumbing system for the first time. Here we use interferometric synthetic aperture radar (InSAR) data from both the Sentinel‐1A and ALOS‐2 satellites to map and analyze the surface deformation at four time periods during the activity. These data allow us to identify the two eruption phases and reveal strong coeruptive subsidence within the Wolf caldera that is superimposed on a larger volcano‐wide subsidence signal. Modeling of the surface displacements shows that two shallow magma reservoirs located under Wolf at ~1 km and ~5 km below sea level explain the subsidence and that these reservoirs appear to be hydraulically connected. We also suggest that the transition from the circumferential to the intracaldera eruption may have involved ring fault activity.
Key Points
The 2015 Wolf volcano (Galápagos) eruption studied using both Sentinel‐1A and ALOS‐2 satellite radar data
Coeruption deformation explained with two magma reservoirs at 1 km and 5 km depths below sea level that may be hydraulically connected
Observed ground deformation may have been influenced by ring fault activity
Zircon Dates Long‐Lived Plume Dynamics in Oceanic Islands Rojas‐Agramonte, Yamirka; Kaus, Boris J. P.; Piccolo, Andrea ...
Geochemistry, geophysics, geosystems : G3,
November 2022, 2022-11-00, 20221101, 2022-11-01, Letnik:
23, Številka:
11
Journal Article
Recenzirano
Odprti dostop
In this contribution we report the first systematic study of zircon U‐Pb geochronology and δ18O‐εHf(t) isotope geochemistry from 10 islands of the hot‐spot related Galapagos Archipelago. The data ...extracted from the zircons allow them to be grouped into three types: (a) young zircons (0–∼4 Ma) with εHf(t) (∼5–13) and δ18O (∼4–7) isotopic mantle signature with crystallization ages dating the islands, (b) zircons with εHf(t) (∼5–13) and δ18O (∼5–7) isotopic mantle signature (∼4–164 Ma) which are interpreted to date the time of plume activity below the islands (∼164 Ma is the minimum time of impingement of the plume below the lithosphere), and (c) very old zircons (∼213–3,000 Ma) with mostly continental (but also juvenile) εHf(t) (∼−28–8) and δ18O (∼5–11) isotopic values documenting potential contamination from a number of sources. The first two types with similar isotopic mantle signature define what we call the Galápagos Plume Array (GPA). Given lithospheric plate motion, this result implies that GPA zircon predating the Galápagos lithosphere (i.e., >14–164 Ma) formed and were stored at sublithospheric depths for extended periods of time. In order to explain these observations, we performed 2D and 3D thermo‐mechanical numerical experiments of plume‐lithosphere interaction which show that dynamic plume activity gives rise to complex asthenospheric flow patterns and results in distinct long‐lasting mantle domains beneath a moving lithosphere. This demonstrates that it is physically plausible that old plume‐derived zircons survive at asthenospheric depths below ocean islands.
Key Points
Our data define the Galápagos Plume Array defined by mantle εHf(t) and δ18O values in the range ∼0–164 Ma
This finding allows dating back plume activity to, at least, early Middle Jurassic (∼164 Ma)
Numerical experiments confirm it is plausible that old Plume‐derived zircons survive in the asthenosphere for extended periods of time
The Galapagos Harpp, Karen S; Harpp, Karen S; Mittelstaedt, Eric ...
2014., 2014, 2014-07-15, Letnik:
204
eBook
The Galápagos Islands are renown for their unique flora and fauna, inspiring Charles Darwin in the elaboration of his theory of evolution. Yet in his Voyage of the Beagle, published in 1839, Darwin ...also remarked on the fascinating geology and volcanic origin of these enchanted Islands. Since then, the Galápagos continue to provide scientists with inspiration and invaluable information about ocean island formation and evolution, mantle plumes, and the deep Earth. Motivated by an interdisciplinary Chapman Conference held in the Islands, this AGU volume provides cross-disciplinary collection of recent research into the origin and nature of ocean islands, from their deepest roots in Earth's mantle, to volcanism, surface processes, and the interface between geology and biodiversity. Volume highlights include: Case studies in biogeographical, hydrological, and chronological perspective Understanding the connection between geological processes and biodiversity Synthesis of decades of interdisciplinary research in physical processes from surface to deep interior of the earth In-depth discussion of the concept of the island acting as a natural laboratory for earth scientists Integrated understanding of the Galápagos region from a geological perspective Collectively, The Galápagos presents case studies illustrating the Galápagos Archipelago as a dynamic natural laboratory for the earth sciences. This book would be of special interest to a multidisciplinary audience in earth sciences, including petrologists, volcanologists, geochronologists, geochemists, and geobiologists.
Abstract
The physicochemical characteristics of sub-volcanic magma storage regions have important implications for magma system dynamics and pre-eruptive behaviour. The architecture of magma storage ...regions located directly above high buoyancy flux mantle plumes (such as Kīlauea, Hawai’i and Fernandina, Galápagos) are relatively well understood. However, far fewer constraints exist on the nature of magma storage beneath ocean island volcanoes that are distal to the main zone of mantle upwelling or above low buoyancy flux plumes, despite these systems representing a substantial proportion of ocean island volcanism globally. To address this, we present a detailed petrological study of Isla Floreana in the Galápagos Archipelago, which lies at the periphery of the upwelling mantle plume and is thus characterized by an extremely low flux of magma into the lithosphere. Detailed in situ major and trace element analyses of crystal phases within exhumed cumulate xenoliths, lavas and scoria deposits indicate that the erupted crystal cargo is dominated by disaggregated crystal-rich material (i.e. mush or wall rock). Trace element disequilibria between cumulus phases and erupted melts, as well as trace element zoning within the xenolithic clinopyroxenes, reveal that reactive porous flow (previously identified beneath mid-ocean ridges) is an important process of melt transport within crystal-rich magma storage regions. In addition, application of three petrological barometers reveals that the Floreana mush zones are located in the upper mantle, at a depth of 23·7 ± 5·1 km. Our barometric results are compared with recent studies of high melt flux volcanoes in the western Galápagos, and other ocean island volcanoes worldwide, and demonstrate that the flux of magma from the underlying mantle source represents a first-order control on the depth and physical characteristics of magma storage.
At the Galapagos triple junction in the equatorial Pacific Ocean, the Cocos‐Nazca spreading center does not meet the East Pacific Rise (EPR) but, instead, rifts into 0.4 Myr‐old lithosphere on the ...EPR flank. Westward propagation of Cocos‐Nazca spreading forms the V‐shaped Galapagos gore. Since ~1.4 Ma, opening at the active gore tip has been within the Cocos‐Galapagos microplate spreading regime. In this paper, bathymetry, magnetic, and gravity data collected over the first 400 km east of the gore tip are used to examine rifting of young lithosphere and transition to magmatic spreading segments. From inception, the axis shows structural segmentation consisting of rifted basins whose bounding faults eventually mark the gore edges. Rifting progresses to magmatic spreading over the first three segments (s1–s3), which open between Cocos‐Galapagos microplate at the presently slow rates of ~19–29 mm/year. Segments s4–s9 originated in the faster‐spreading (~48 mm/year) Cocos‐Nazca regime, and well‐defined magnetic anomalies and abyssal hill fabric close to the gore edges show the transition to full magmatic spreading was more rapid than at present time. Magnetic lineations show a 20% increase in the Cocos‐Nazca spreading rate after 1.1 Ma. The near‐axis Mantle Bouguer gravity anomaly decreases eastward and becomes more circular, suggesting mantle upwelling, increasing temperatures, and perhaps progression to a developed melt supply beneath segments. Westward propagation of individual Cocos‐Nazca segments is common with rates ranging between 12 and 54 mm/year. Segment lengths and lateral offsets between segments increase, in general, with distance from the tip of the gore.
Plain Language Summary
A fundamental question in the study of mid‐ocean ridges is how spreading centers initiate and change through time. At the Galapagos triple junction in the equatorial Pacific, the oceanic crust is being broken apart to form rift basins, which develop into individual mid‐ocean ridge spreading segments. Bathymetry, magnetic, and gravity data were collected to help understand the stages in the transition from rift basins to a magmatic seafloor spreading center. From inception, the developing spreading center is composed of individual segments that are offset from each other. Currently, rifting progresses to magmatic spreading over three segments, which opened at slow spreading rates. Older spreading segments originated at faster‐spreading rates. Data indicate that the change from rifting to full magmatic spreading was more rapid in these older segments. Near the spreading axis, gravity data show that temperatures increase beneath segments as they mature, suggesting that magma supply is developing beneath the segments. Propagation of the western ends of segments is common. Understanding how seafloor spreading initiates and forms a segmented mid‐ocean ridge provides information on how mantle melting is established beneath a rift zone and how tectonic plate boundaries evolve.
Key Points
At the Galapagos triple junction rifting changes to full magmatic spreading in stages within the Cocos‐Galapagos microplate spreading regime
Magnetic anomalies and linear off‐axis topography show magmatic spreading developed rapidly when opening was between Cocos and Nazca plates
Initial segment lengths at the tip of the Galapagos gore appear constant at ~20 km, but segment lengths are larger farther from the tip
We present a review of small baseline interferometric synthetic aperture radar (InSAR) time series analysis with a new processing workflow and software implemented in Python, named MintPy ...(https://github.com/insarlab/MintPy). The time series analysis is formulated as a weighted least squares inversion. The inversion is unbiased for a fully connected network of interferograms without multiple subsets, such as provided by modern SAR satellites with small orbital tube and short revisit time. In the routine workflow, we first invert the interferogram stack for the raw phase time-series, then correct for the deterministic phase components: the tropospheric delay (using global atmospheric models or the delay-elevation ratio), the topographic residual and/or phase ramp, to obtain the noise-reduced displacement time-series. Next, we estimate the average velocity excluding noisy SAR acquisitions, which are identified using an outlier detection method based on the root mean square of the residual phase. The routine workflow includes three new methods to correct or exclude phase-unwrapping errors for two-dimensional algorithms: (i) the bridging method connecting reliable regions with minimum spanning tree bridges (particularly suitable for islands), (ii) the phase closure method exploiting the conservativeness of the integer ambiguity of interferogram triplets (well suited for highly redundant networks), and (iii) coherence-based network modification to identify and exclude interferograms with remaining coherent phase-unwrapping errors. We apply the routine workflow to the Galápagos volcanoes using Sentinel-1 and ALOS-1 data, assess the qualities of the essential steps in the workflow and compare the results with independent GPS measurements. We discuss the advantages and limitations of temporal coherence as a reliability measure, evaluate the impact of network redundancy on the precision and reliability of the InSAR measurements and its practical implication for interferometric pairs selection. A comparison with another open-source time series analysis software demonstrates the superior performance of the approach implemented in MintPy in challenging scenarios.
Display omitted
•Two phase-unwrapping error correction methods based on bridging and phase closure.•A new workflow for InSAR time series analysis with post-inversion phase correction.•Applications to Sentinel-1 and ALOS-1 data on Galápagos volcanoes, Ecuador.•An open-source Python toolbox (MintPy) with examples in Jupyter Notebook.•Compare four InSAR time-series approaches in MintPy and GIAnT.
The skull often reveals adaptation to ecological and environmental influences. Food availability affects the somatic growth of otariids, and population abundance can influence male intrasexual ...competition. We hypothesized there would be regional differences between Galapagos sea lion (GSL, Zalophus wollebaeki) rookeries as a result of variance in ecosystem metrics and population abundance. We used skull measures related to individual size and aggressiveness. We analyzed 19 linear measures for size and 15 for aggressiveness taken on 49 adult male skulls of GSL collected in four bioregions of the archipelago. Nine skull measures had a significant effect on individual clustering into bioregions (P < 0.001). The most discriminating measures were snout length, supraorbital process width, nasal length, and canine width. We found a significant relationship between skull grouping patterns and chlorophyll-α levels (proxy marine productivity and body growth) and GSL population abundance (proxy of agonistic behavior) of each bioregion, as well as with the interaction between both variables (P < 0.001). Our results suggest significant regional differences in GSL skull morphometry, which could be associated with resource availability and level of male intrasexual competition in the archipelago. This information is important for understanding the life history of this species. El cráneo es útil para mostrar los efectos de adaptación de las especies a diferentes influencias ecológicas y ambientales. Basados en que la disponibilidad de alimento afecta al crecimiento somático de los otáridos y que la abundancia poblacional puede afectar la competencia intrasexual en machos, pensamos que podría existir diferencias regionales entre las colonias del lobo marino de Galápagos (LMG, Zalophus wollebaeki) como resultado de la variabilidad ambiental y distintas abundancias poblacionales. Usamos medidas craneales relacionadas con el tamaño del individuo (secciones que definen sólo crecimiento) y la agresividad (áreas de inserción de músculos asociados con su comportamiento antagonista). En este contexto, se analizaron 19 medidas lineales para tamaño y 15 para agresividad tomadas en 49 cráneos de machos adultos de LMG. Con base en información ecológica, se dividió el archipiélago en cuatro biorregiones: norte (n = 7), oeste (n = 16), centro (n = 8), y sureste (n = 18). El mejor modelo de análisis discriminante flexible basado en el criterio Lambda de Wilk (P < 0,001), contenía nueve de las medidas del cráneo que tuvieron un efecto significativo en la agrupación individual de las biorregiones (P < 0.001). Las medidas más discriminatorias fueron la longitud del hocico: SL, ancho proceso supraorbital: SPW, longitud nasal: NL y ancho canino: CW (Lambda de Wilk P < 0.3). Encontramos una asociación significativa entre los patrones de agrupamiento del cráneo con los niveles de clorofila-α (proxy de productividad marina y crecimiento corporal) y la abundancia de población GSL (proxy de comportamiento agonista) de cada biorregión, así como con la interacción entre ambas variables (modelo lineal). Nuestros resultados sugieren diferencias regionales en la morfometría del LMG, que podrían estar asociadas con una distinta disponibilidad de recursos y nivel de competencia intrasexual en machos en el archipiélago. Esta información es relevante para entender la historia de vida de esta especie, así como sus oportunidades y amenazas.
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