Search for: All records

Iron oxide-apatite (IOA) deposits, also known as magnetite-apatite or Kiruna-type deposits, are a major source of iron and potentially of rare earth elements and phosphorus. To date, the youngest representative of this group is the Pleistocene (~2 Ma) El Laco deposit, located in the Andean Cordillera of northern Chile. El Laco is considered a unique type of IOA deposit because of its young age and its volcanic-like features. Here we report the occurrence of similarly young IOA-type mineralization hosted within the Laguna del Maule Volcanic Complex, an unusually large and recent silicic volcanic system in the south-central Andes. We combined field observations and aerial drone images with detailed petrographic observations, electron microprobe analysis (EMPA), and 40Ar/39Ar dating to characterize the magnetite mineralization—named here “Vetas del Maule”—hosted within andesites of the now extinct La Zorra volcano (40Ar/39Ar plateau age of 1.013 ± 0.028 Ma). Five different styles of magnetite mineralization were identified: (1) massive magnetite, (2) pyroxene-actinolite-magnetite veins, (3) magnetite hydrothermal breccias, (4) disseminated magnetite, and (5) pyroxene-actinolite veins with minor magnetite. Field observations and aerial drone imaging, coupled with microtextural and microanalytical data, suggest a predominantly hydrothermal origin for the different types of mineralization. 40Ar/39Ar incremental heating of phlogopite associated with the magnetite mineralization yielded a plateau age of 873.6 ± 30.3 ka, confirming that the emplacement of Vetas del Maule postdated that of the host andesite rocks. Our data support the hypothesis that the magnetite mineralization formed in a volcanic setting from Fe-rich fluids exsolved from a magma at depth. Ultimately, Vetas del Maule provides evidence that volcanic-related IOA mineralization may be more common than previously thought, opening new opportunities of research and exploration for this ore deposit type in active volcanic arcs. 

Abstract. Robust projections and predictions of climate variability and change, particularly at regional scales, rely on the driving processes being represented with fidelity in model simulations. Consequently, the role of enhanced horizontal resolution in improved process representation in all components of the climate system continues to be of great interest. Recent simulations suggest the possibility of significant changes in both large-scale aspects of the ocean and atmospheric circulations and in the regional responses to climate change, as well as improvements in representations of small-scale processes and extremes, when resolution is enhanced. The first phase of the High-Resolution Model Intercomparison Project (HighResMIP1) was successful at producing a baseline multi-model assessment of global simulations with model grid spacings of 25–50 km in the atmosphere and 10–25 km in the ocean, a significant increase when compared to models with standard resolutions on the order of 1° that are typically used as part of the Coupled Model Intercomparison Project (CMIP) experiments. In addition to over 250 peer-reviewed manuscripts using the published HighResMIP1 datasets, the results were widely cited in the Intergovernmental Panel on Climate Change report and were the basis of a variety of derived datasets, including tracked cyclones (both tropical and extratropical), river discharge, storm surge, and impact studies. There were also suggestions from the few ocean eddy-rich coupled simulations that aspects of climate variability and change might be significantly influenced by improved process representation in such models. The compromises that HighResMIP1 made should now be revisited, given the recent major advances in modelling and computing resources. Aspects that will be reconsidered include experimental design and simulation length, complexity, and resolution. In addition, larger ensemble sizes and a wider range of future scenarios would enhance the applicability of HighResMIP. Therefore, we propose the High-Resolution Model Intercomparison Project phase 2 (HighResMIP2) to improve and extend the previous work, to address new science questions, and to further advance our understanding of the role of horizontal resolution (and hence process representation) in state-of-the-art climate simulations. With further increases in high-performance computing resources and modelling advances, along with the ability to take full advantage of these computational resources, an enhanced investigation of the drivers and consequences of variability and change in both large- and synoptic-scale weather and climate is now possible. With the arrival of global cloud-resolving models (currently run for relatively short timescales), there is also an opportunity to improve links between such models and more traditional CMIP models, with HighResMIP providing a bridge to link understanding between these domains. HighResMIP also aims to link to other CMIP projects and international efforts such as the World Climate Research Program lighthouse activities and various digital twin initiatives. It also has the potential to be used as training and validation data for the fast-evolving machine learning climate models. 

Abstract Purpose of Review Assessment of the impact of ocean resolution in Earth System models on the mean state, variability, and future projections and discussion of prospects for improved parameterisations to represent the ocean mesoscale. Recent Findings The majority of centres participating in CMIP6 employ ocean components with resolutions of about 1 degree in their full Earth System models (eddy-parameterising models). In contrast, there are also models submitted to CMIP6 (both DECK and HighResMIP) that employ ocean components of approximately 1/4 degree and 1/10 degree (eddy-present and eddy-rich models). Evidence to date suggests that whether the ocean mesoscale is explicitly represented or parameterised affects not only the mean state of the ocean but also the climate variability and the future climate response, particularly in terms of the Atlantic meridional overturning circulation (AMOC) and the Southern Ocean. Recent developments in scale-aware parameterisations of the mesoscale are being developed and will be included in future Earth System models. Summary Although the choice of ocean resolution in Earth System models will always be limited by computational considerations, for the foreseeable future, this choice is likely to affect projections of climate variability and change as well as other aspects of the Earth System. Future Earth System models will be able to choose increased ocean resolution and/or improved parameterisation of processes to capture physical processes with greater fidelity.