The Montecristo mining district, northern Chile: the relationship between vein‑like magnetite‑(apatite) and iron oxide‑copper–gold deposits

The Montecristo district, northern Chile, is one of the few places worldwide where there is a direct relationship between magnetite-(apatite) (MtAp) mineralization and iron oxide-copper–gold (IOCG) mineralization. The MtAp mineralization includes Ti-poor magnetite, fluorapatite, and actinolite and is crosscut and partially replaced by a younger IOCG mineralization that includes a second generation of actinolite and magnetite with quartz, chalcopyrite, pyrite, and molybdenite. The MtAp stage at Montecristo is interpreted as the crystallized iron-rich melts that used the pre-existing structures of the Atacama Fault System as conduits. These rocks later acted as a trap for hydrothermal IOCG mineralization. Geochronology data at Montecristo indicate that the host diorite (U–Pb zircon 153.3 ± 1.8 Ma, 2-sigma), MtAp mineralization (40Ar-39Ar in actinolite, 154 ± 2 Ma and 153 ± 4 Ma, 2-sigma), and the IOCG event (Re-Os on molybdenite, 151.8 ± 0.6 Ma, 2-sigma) are coeval within error and took place in a time span of less than 3.4 Ma. The εHfi and εNdi values of the host diorite are + 8.0 to + 9.8 and + 4.3 to + 5.4, respectively. The whole-rock 87Sr/86Sri values of the IOCG mineralization (0.70425 to 0.70442) are in the lower end of those of the MtAp mineralization (0.70426–0.70629). In contrast, εNdi values for the IOCG mineralization (+ 5.4 and + 5.7) fall between those of the MtAp rocks (+ 6.6 to + 7.2) and the host diorite, which suggests that the IOCG event was related to fluids having a more crustal Nd (εNdi < + 5.7) composition than the MtAp mineralization. This likely reflects the mixing of Nd from the MtAp protolith and a deep magmatic-hydrothermal source, very likely an unexposed intrusion equivalent to the host diorite. Sulfur isotope compositions (δ34S, + 0.3 to + 3.4‰) are consistent with a magmatic source.NSERC discovery grant to J.M. Hanchar (RGPIN/004649-2015)RTI2018-099157-A-I00 (MCI/AEI/FEDER, UE) research grant to F. Tornos

Trophic connectivity between the terrestrial and marine ecosystems of Malpelo Island, Colombia, evaluated through stable isotope analysis

Living beings inhabit heterogeneous environments, in which communities that are classified as discrete can be continuous and connected in innumerable ways. The components of food webs can cross borders between ecosystems, and as result, the structure and trophic dynamics of ecosystems can change. The goal of this study was to evaluate trophic connectivity between the terrestrial and marine ecosystems of Malpelo Island, Colombia (4º00’05.63” N; 81º36’36.41” W), based on the isotopic (δ13C and δ15N) assessment of 403 samples (107 terrestrial and 296 marine). Samples were collected in 2017–2021. δ13CTerrestrial values ranged from − 30.3‰ to − 15.0‰ and δ13CMarine ranged from − 24.0‰ to − 9.8‰; δ15NTerrestrial ranged from 3.7‰ to 21.3‰ and δ15NMarine ranged from 4.5 to 16.9‰. The mixing model (simmr package) indicated that detritusTerrestrial (δ13C = − 18.9 ± 0.30‰ SE) contributed more to the food web than C3 plants (–29.4 ± 0.22‰), and reflected high δ13CMarine content. There was high isotopic overlap (65–82%) and a high trophic connection between environments of Malpelo Island due to high similarity between isospaces. These results evidence the role of the donor habitat (marine) on the receptor habitat (terrestrial) and the role of the Nazca booby Sula granti regarding nutrient transfers between the two environments. The presence and preservation of this seabird is essential to maintain the balance of this insular ecosystem. The analysis of δ13C and δ15N tracers was useful to establish the trophic relationships between small oceanic island environments with presence of large seabird communities.Fundacion Alium PacificInstituto Andaluz de Ciencias de la Tierra (CSIC-UGR) National Geographic Society CP-059ER-1

Tracing Mobility Patterns of Buried Species of the Late Iron Age Funerary Staggered Turriform of Son Ferrer (Calvià, Spain)

This work was supported by the project “Comunitats indígenes i contacte cultural al sud-oest de Mallorca a l’edat del ferro. Puig de Sa Morica” financed by Consell Insular de Mallorca; and the R&D Project “Movilidad y conectividad de las comunidades prehistóricas en el Mediterráneo Occidental durante la prehistoria reciente: El caso de las Islas Baleares” (PID2019-108692GB) of the ArchaeoUIB Research Group (Universitat de les Illes Balears) financed by the Spanish Ministry of Science and Innovation. The work of Lua Valenzuela-Suau has been supported by the postdoctoral contract financed by the Ministerio de Universidades, under the Pla de Recuperació, Transformació i Resiliència, and financed by the European Union (NextGenerationEU), with the participation of the Universitat de les Illes Balears. The work of Paloma Salvador has been supported by the predoctoral fellowship (FPI-CAIB) FPI/2245/2019 financed by the Conselleria d’Educació, Cultura i Universitats of the Govern de les Illes Balears and the European Social Fund.This is the first mobility 87Sr/86Sr analysis in human remains made on the Balearic Islands. Eight human individuals buried at the same Late Iron Age funerary chamber of Son Ferrer site (Calvià, Mallorca) have been sampled for strontium and oxygen isotopic analysis (87Sr/86Sr and δ18O). The study includes strontium and oxygen isotopic analysis of domestic mammals buried in the same Funerary Area (FA1) together with present-day vegetation and archaeological bone to assess the strontium isotopic ratios (87Sr/86Sr) around the site. All the results are compatible with the 87Sr/86Sr documented in Mallorca and, more specifically, with the surrounding bedrocks from the site. Humans, caprines, and dogs provided similar results and no significant differences are found between the species. The only exception is a caprine which shows seasonal movement through the period of enamel mineralisation. The isotopic information agrees with the previous studies, which proposed that Son Ferrer site was a symbolic place for the surrounding territory where people from the nearby villages were buried.Consell Insular de MallorcaSpanish Ministry of Science and Innovation PID2019-108692GBMinisterio de Universidades, Pla de Recuperació, Transformació i ResiliènciaEuropean Union (NextGenerationEU)Universitat de les Illes BalearsGovern de les Illes Balears FPI/2245/2019European Social Fun

Tiger sharks support the characterization of the world’s largest seagrass ecosystem

Seagrass conservation is critical formitigating climate change due to the large stocks of carbon they sequester in the seafloor. However, effective conservation and its potential to provide nature-based solutions to climate change is hindered by major uncertainties regarding seagrass extent and distribution. Here, we describe the characterization of the world’s largest seagrass ecosystem, located in The Bahamas. We integrate existing spatial estimates with an updated empirical remote sensing product and perform extensive groundtruthing of seafloor with 2,542 diver surveys across remote sensing tiles. We also leverage seafloor assessments and movement data obtained from instrument-equipped tiger sharks, which have strong fidelity to seagrass ecosystems, to augment and further validate predictions. We report a consensus area of at least 66,000 km2 and up to 92,000km2 of seagrass habitat across The Bahamas Banks. Sediment core analysis of stored organic carbon further confirmed the global relevance of the blue carbon stock in this ecosystem. Data from tiger sharks proved important in supporting mapping and groundtruthing remote sensing estimates. This work provides evidence of major knowledge gaps in the ocean ecosystem, the benefits in partnering with marine animals to address these gaps, and underscores support for rapid protection of oceanic carbon sinks.Beneath The WavesDisney Conservation FundBarry and Mimi Sternlicht FoundationSant FamilyPictet FoundationPacific Treasure FoundationKing FamilyD. and J. Harris, B. Coughlin and FamilyP. Nicholson and WCPD FoundationSouthern TideHillsdaleThayer AcademyDiscovery CommunicationsMary O'Malley and Lupo Dion TrustNational Geographic SocietyJ. Lake and JDL, Inc.Towle Family Ocean FoundationKaro Family TrustScience Foundation Ireland 18/SIRG/5549King Abdullah University of Science & Technology36Pi

Trophic Ecology during the Ontogenetic Development of the Pelagic Thresher Shark Alopias pelagicus in Baja California Sur, Mexico

The trophic ecology of the Pelagic Thresher shark (Alopias pelagicus) was evaluated based on chemical ecology using stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) in the vertebrae and muscles. Individuals were caught between August 2013 and October 2019 on both the coasts of Baja California Sur, Mexico. In Bahía Tortugas, the mean vertebrae (n = 35) values were 12.72 ± 1.06‰ (δ15N) and −14.79 ± 0.61‰ (δ13C), while in muscles (n = 32) these values were 16.63 ± 0.76‰ (δ15N) and −17.18 ± 0.39‰ (δ13C). In Santa Rosalía, the mean vertebrae (n = 125) isotopic values were 14.4 ± 1.59‰ (δ15N) and −14.18 ± 0.51‰ (δ13C), while in muscles (n = 43), these values were 18.08 ± 0.96‰ (δ15N) and −16.43 ± 0.34‰ (δ13C). These results show higher δ15N values in Santa Rosalía as an effect of baseline isotopic differences between the two regions, whereas the δ13C values were lower in Bahía Tortugas, suggesting offshore ecological behavior (p 0.05), suggesting a high overlap between their isotopic niches. Therefore, Alopias pelagicus uses the same ecological niche throughout its life, and there is consistency between sexes. The mean trophic position for both tissues and regions was 4.5, which corresponds to a tertiary predator, without any differences between stages or sex. Due to their higher energetic needs, juveniles and females showed the greatest isotopic niche amplitude; thus, their ecological niche is the widest.Instituto Politécnico Nacional, Project SIP-IPN 2022057

Análisis mineralógicos, petrográficos y geoquímicos confirman el origen hidrotermal de sedimentos metalíferos sobreyaciendo las peridotitas de Cerro Matoso, Colombia

This paper shows part of the Doctoral dissertation of the first author (A. Castrillón), who gratefully acknowledges a fellowship from Colciencias (National Doctorate, scholarship 647) and Universidad Nacional de Colombia. Isotope analyses were done in the Instituto Andaluz de Ciencias de la Tierra, Granada, Spain. The authors express their gratitude to Dr. Dario Barrero, for his comments, and to Dr. Brian Fry for his selfless collaboration and valuable contributions to isotope modeling, and thanks to Cerro Matoso. This work also was possible thanks to the support of Dr. Augusto Rodriguez and the Instituto de Geología and Instituto de Geofísica Ambiental from the Universidad Nacional Autónoma de México. Datasets for this research are included in this paper and supplementary information files can be found in. Castrillón, Andres (2020), “Open systems fractionation factor CM”, Mendeley Data, v1. https://doi.org/10.17632/8fr82mx34x.1#file- 51080efe-3098-4796-a5ae-384707ae2ddbThe Cerro Matoso deposit, one of the largest open-pit ferronickel mines in the world is formed by a sedimentary succession on top of an abducted ultramafic body that makes part of the Cauca ophiolite complex. The set of rocks was accreted in northwestern Colombia during the Cretaceous and exposed to weathering processes during the last Andean Orogeny. Sediment samples were collected and studied using petrographic microscopy, SEM, EPMA, ICP-MS, XRF, and oxygen as well as carbon isotopes analyses. Oxygen isotope results reflect pore-water temperatures reaching up to 130 degrees C during mineral precipitation, which are consistent with serpentinization-derived fluids of mantle rocks that may be related to deep-sea hydrothermal activity. Negative delta 13C values (-27.1 to -1 parts per thousand V-PDB) in bulk samples of the tabular succession correlate with the delta 13C range of methane from modern serpentinite-derived fluids. The REE/Fe data (ratio <0.4) suggest that sediments differenced in black mudstone and fossiliferous green claystone correspond to metalliferous and hydrothermal sediments respectively, formed in the ancient mid-ocean Pacific ridge, far west of its present position. Positive Eu and negative Ce anomalies registered in the black mudstone succession correlate with a hydrothermal plume scenario.El yacimiento Cerro Matoso, una de las minas de ferroníquel a cielo abierto más grandes del mundo, está formado por una sucesión sedimentaria que reposa sobre un cuerpo ultramáfico adosado al continente, que forma parte del Complejo Ofiolítico del Cauca. El conjunto de rocas fue adosado en el noroeste de Colombia durante el Cretácico, y fue expuesto a procesos de meteorización durante la última orogenia andina. Las muestras de sedimentos fueron recolectadas y estudiadas mediante microscopía petrográfica, SEM, EPMA, ICP-MS, FRX y análisis de isótopos de oxígeno y carbono. Los resultados de los isótopos de oxígeno reflejan temperaturas del agua intersticial que alcanzan los 130°C durante la precipitación mineral, lo que es coherente con fluidos derivados de la serpentinización de las rocas ultramáficas que pueden estar relacionados con actividad hidrotermal en el fondo del mar. Los valores negativos de δ13C (−27,1 a −1‰ V-PDB) en muestras (roca total) de la sucesión sedimentaria, se correlacionan con el rango de δ13C del metano de fluidos modernos derivados de serpentinita. Los datos REE/Fe (relación <0.4) sugieren que los sedimentos denominados lodolitas negras y arcillolitas verdes fosilíferas corresponden a sedimentos metalíferos e hidrotermales respectivamente, formados en la antigua dorsal meso-oceánica del océano Pacífico, muy al oeste de su posición actual. Las anomalías positivas de Eu y negativas de Ce registradas en la sucesión de lodolitas negras se correlacionan con un escenario de plumas hidrotermalesDepartamento Administrativo de Ciencia, Tecnologia e Innovacion Colciencias 64

Water use efficiency and climate legacies dominate beech growth at its rear edge

Rear-edge tree populations are experiencing a combination of higher temperatures and more intense droughts that might push individuals beyond their tolerance limits. This trend towards rising atmospheric [CO2] is concurrent with an increase in intrinsic water use efficiency (iWUE), which theoretically enhances photosynthesis and decrease evapotranspiration rates, consequently improving tree resistance to drought. However, it remains unclear whether iWUE is favouring tree growth under current climate conditions, particularly when climate and iWUE legacy effects are simultaneously considered. 2. We evaluated this question with an extensive sampling along Iberian rear-edge (dry) populations comprising four mountain ranges and two distinct altitudes. We simultaneously examined the effects of climate and iWUE on secondary growth using annually resolved basal area increments (BAIs) for the period 1901–2017. We used linear mixed models including second-order autocorrelation and 1-year legacy effects of iWUE and summer drought. 3. BAI and iWUE increased across the studied period. iWUE increase was driven by changes in atmospheric CO2 concentration and water availability during the growing season. Climate and iWUE exerted direct and lagged effects on beech growth. Water availability during growing season was the main driver of tree growth, combining direct and indirect effects through its impact on iWUE. Legacy effects of water availability and iWUE were more important than growing season conditions. The net effect of iWUE shifted when lagged effects were considered, resulting in a net negative impact on tree growth. 4. Synthesis: Our results reveal that climate and iWUE legacy effects must be considered to assess the net iWUE effect on secondary growth. Considering lagged effects, the current increase in iWUE is constraining tree growth. Modelling efforts of tree growth response to climate warming should include climate and iWUE legacy effects to adequately assess terrestrial ecosystem carbon balanceEU Feder Funds; EU LIFE, Grant/Award NumberLIFE Soria Forest Adapt [LIFE19 CCA/ES/001181Junta de Castilla y León-Consejería de Educación, Grant/ Award Number: IR2020-1- UVA08; VA171P20Spanish Ministry for Science and Innovation, Grant/Award Number: LAUREL PID2019-109906RA- I00 MCIN/AEI/10.13039/5011PROWARM PID2020-118444GA- 100 MCIN/ AEI/10.13039/50Postdoctoral grant IJC2019-040571- I MCIN/ AEI/10.13Predoctoral grant PRE2018-084106 funded by MCIN/AEspRING CGL2017-87309- P MCIN/ AEI/10.13039/50110001

Determining Seasonal Natural Effects over Isotopic Baselines for CO2 Storage Monitoring

AbstractDissolved carbon stable isotopes in surface waters can be utilized as a monitoring tool of CO2 geological storage and as a good indicator of potential CO2 leakages, since each source of carbon has a specific isotopic signature. The isotopic carbon baseline value and its range will determine whether the situation responds to a leak or a natural modification as part of the system's annual cycle and its seasonal effects. We measured water temperature, pH, dissolved inorganic carbon (DIC) concentration and other geochemical variables, during the different annual stages, in order to characterize the contribution of different sources of carbon to the natural isotopic evolution of DIC in the area of Hontomin. This area is the selected site for the Spanish research facility for CO2 geological storage operated by CIUDEN. The average value for δ13C-DIC at the study site is -10.7 ‰ (V-PDB), which is very different of the CO2 generated during the oxycombustion process (about -28 ‰ vs V-PDB). After statistical analysis of the sampling efforts, we observed light differences on their average isotopic values which imply certain seasonal effects, although we could not find effects over the DIC concentration

Improvement Options of a Social Housing Prototype in Different Climate Zones in Ecuador

Ecuador is a country with several climate zones. The zones’ characteristics are very different; however, there are social housing prototypes used in all the territories. This study constitutes the second part of the analysis of a social housing prototype in four zones (Cfb, Af, Aw, and BSh) in both the current climate situation (2020) and its projection to 2050. Improvement measures from the original dwelling block have been proposed according to the initial diagnosis, considering seven passive performance variants. A total of 56 dynamic simulations have been performed for both the current and 2050 climate scenario. The results have shown that, depending on the climate zone, improvement measures differently influence comfort ranges. In addition, the behaviour of the dwellings on the upper floor is different from those on the ground floor. This study is a starting point to show that prototype solutions of social housing should be adapted with various improvement measures and should be based on specific requirements according to their location to achieve acceptable comfort levels

High-resolution variability of dissolved and suspended organic matter in the Cape Verde Frontal Zone

Distributions of dissolved (DOM) and suspended (POM) organic matter, and their chromophoric (CDOM) and fluorescent (FDOM) fractions, are investigated at high resolution (< 10 km) in the Cape Verde Frontal Zone (CVFZ) during fall 2017. In the epipelagic layer (< 200 m), meso- and submesoscale structures (meanders, eddies) captured by the high resolution sampling dictate the tight coupling between physical and biogeochemical parameters at the front. Remarkably, fluorescent humic-like substances show relatively high fluorescence intensities between 50 and 150 m, apparently not related to local mineralization processes. We hypothesize that it is due to the input of Sahara dust, which transports highly re-worked DOM with distinctive optical properties. In the mesopelagic layer (200-1500 m), our results suggest that DOM and POM mineralization occurs mainly during the transit of the water masses from the formation sites to the CVFZ. Therefore, most of the local mineralization seems to be due to fast-sinking POM produced in situ or imported from the Mauritanian upwelling. These local mineralization processes lead to the production of refractory CDOM, an empirical evidence of the microbial carbon pump mechanism. DOM released from these fastsinking POM is the likely reason behind the observed columns of relatively high DOC surrounded by areas of lower concentration. DOM and POM dynamics in the CVFZ has turned out to be very complex, in parallel to the complexity of meso- and submesoscale structures present in the area. On top of this high resolution variability, the input of Sahara dust or the release of DOM from sinking particles have been hypothesized to explain the observed distributions.Spanish National Science Plan research grant FERMIO CTM2014-57334-JINSpanish National Science Plan research grant FLUXES CTM2015-69392-C3European Commission eIMPACT PID2019-109084RB-C21 PID2019-109084RB-C22Ministry of Science and Innovation, Spain (MICINN)Spanish Government BES-2016-076462 BES2016-079216 BES-2016-077949Juan de la Cierva Formacion fellowship FJCI-641-2015-25712European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant 834330project SUMMER from the European Union's Horizon 2020 research and innovation program AMD-817806-