Mercury is unique among terrestrial planets because of its very high metal/silicate ratio. The NASA MESSENGER mission ended in 2015 and significantly advanced our understanding of the deep structure of the planet as well as our comprehension of Mercury’s volcanic history and crust formation. The European Space Agency (ESA) recently launched the BepiColombo mission in October 2018. The “Planet Mercury” issue summarizes the latest developments in light of MESSENGER data and perspectives for the BepiColombo mission on internal structures and surface processes, based on insights from geophysics, geochemistry, igneous and experimental petrology and volcanology.
Reactive transport modeling, or computer simulations of the transfer of mass and energy through the subsurface, has become a central tool for understanding how Earth’s unique chemical environments are formed, how they function today, and how they might behave in the future. This process-based approach has enabled us to gain a new understanding of a diverse array of Earth processes, from biogeochemical cycles in marine sediments and the factors that control soil formation, to the evolution of contaminated groundwater systems and the engineered containment of nuclear waste. The diverse contributions in this issue will highlight the unique role that reactive transport models have played in advancing our understanding of Earth’s shallow crustal environments and our human interactions with them.
The South Aegean volcanic arc lies at the intersection between Europe, Asia, and Africa, in the cradle of European civilization. Studies over the last decade have transformed our understanding of the arc: subduction architecture and back-arc geodynamics, genesis of the arc magmas, eruption chronology of the arc recorded in marine tephra archives, and hazards posed by eruptions and tsunamis. Santorini is one of the most explosive arc volcanoes in the world, and its ‘Minoan’ eruption of the Late Bronze Age is an iconic event in volcanology and archaeology. Santorini is still dangerous. The Kolumbo submarine crater, best known for its deadly eruption of 1650, today hosts a hydrothermal system and bacterial colonies. In the eastern sector of the arc lies the large submarine caldera formed by the Kos Plateau Tuff eruption. The eruptive mechanisms and petrology of this eruption have now been unraveled, as have the eruptive and magmatic histories of Nisyros and Yali volcanoes on the caldera rim.
August 2019 - Weathering Across the Earth Sciences
Weathering processes play and integral role across a range of geoscience fields. Chemical weathering – the loss of mass by mineral dissolution and export – is key to understanding how Earth’s skin functions. Weathering is the starting point for the biogeochemical cycles of most elements. It determines river and groundwater chemistry and provides nutrients to ecosystems. Weathering alters rock structure and susceptibility to erosion; soil and landscape evolution cannot be understood without considering the role of chemical weathering. Weathering of silicate rocks is a long-term sink for atmospheric CO2, and has been crucial in maintaining our planet’s habitability over billions of years … and may constitute a geoengineering strategy. This issue explores the linkages between them.
October 2019 - Catastrophic Perturbatons to Earth's Deep Carbon Cycle
Carbon is one of the most important elements on Earth. It is the basis of all life on the planet, is stored and mobilized throughout the Earth from core to crust, and is the basis of the energy sources that are so important to human civilization. This issue will explore the origins of carbon on Earth; the long-term carbon cycle; catastrophic and large-scale perturbations to Earth’s carbon cycle such as large igneous provinces and bolide impacts; carbon’s role in mass extinctions; and icehouse–greenhouse climate transitions in deep time. Deciphering the complex, and often faint, signals of distant carbon catastrophes requires a multidisciplinary effort and the most innovative analytical technology. This thematic collection comes at an important time in which carbon fluxes on Earth are changing rapidly. Society must understand the way in which the deep carbon cycle on Earth works to secure a sustainable future.
Kimberlites are the most deeply derived of all volcanic rocks, as well as the host rock for most of the world’s diamond mines. Kimberlites, therefore, provide unique snap-shots of magma genesis and mantle evolution in the deep Earth well into the diamond stability field (>150 km and, potentially, >700 km). Despite over 100 years of study, the origin of this complex rock-type remains the subject of intense debate. This thematic issue will summarize current knowledge and controversies on kimberlite formation, including key aspects of the petrology, geochemistry and volcanology of these unique rocks. It will show how kimberlites can be successfully dated, and explore links between the temporal and spatial distribution of kimberlites and known geological events. Diamond exploration and resource evaluation methods will be reviewed to demonstrate the inextricable link between an accurate understanding of the characteristics of kimberlites, their entrained mantle cargo, and diamonds.