The Mars Science Laboratory (MSL) rover Curiosity was designed and built to explore the surface of Mars and characterize its modern environment. Its primary objective was to search for ancient habitable environments. During its nominal one-Mars-year mission (23 Earth months), Curiosity drilled and scooped samples, made mineralogical, isotopic, and compositional measurements, took hundreds of thousands of images that provided geologic context for samples, and acquired millions of observations of the modern environment.Curiosity is the most advanced mobile geochemistry laboratory to have ever roved another planet, and it has been very productive. Within 8 months of landing, scientists were able to confirm mission success with evidence of an ancient habitable environment on Mars. This issue presents the range of discoveries related to the investigations of the solid materials at Gale Crater and elsewhere on Mars. [Grotzinger et al. (2015) Elements 11:19-26]
The differentiation of our planet and formation of the continental crust, and its underlying mantle lithosphere, are in large part the result of magmatic processes at convergent margins. These magmatic processes are important to issues of societal interest such as the evolution of life, mineral and energy deposits, volcanic and fault hazards, and long-term climate change. Magmatism in oceanic and continental convergent arcs is not temporally or spatially steady-state, rather it occurs in pulses and lulls. The articles in this issue explore the tempo of magmatism as recorded in the rock record, investigate the causes of high-volume events in subduction-related magmas, and provide an overview of recently developed models to explain episodic behavior in subduction magmatism.
Apatite, number 5 on the Mohs scale of hardness, is one of the first minerals that students of geology learn. Because it was commonly confused with other minerals, apatite was not recognized as a distinct mineral species until the late 18th century. The name apatite is derived from the Greek wordά which means "to deceive." Despite what early mineralogists may have thought of its "deceptive" nature, over the next two centuries apatite was gradually recognized to be the most common phosphate mineral in the Earth’s crust and lithospheric mantle where it subsequently acts as a major reservoir for P, F, Cl, OH, CO2, and many trace elements including the rare earths. This issue introduces apatite as a ubiquitous accessory mineral, which is also related to a supergroup family of over 40 other minerals, and then explores its multi-varied roles as a recorder of both terrestrial and extraterrestrial metasomatic and igneous processes, as a thermochronometer over a wide pressure-temperature range, and as a mineral with numerous technological and biological applications.
August 2015 - Societal and Economic Impacts of Geochemistry
Geochemistry can be applied to a variety of societally and economically important areas, including: mineral exploration; environmental mineralogy; environmental problems in cities, using London (England) as a case study; food industry authenticity; law enforcement; and medical advancements. A significant driver for the research described in all of these articles is analytical achievement and translating this to a societal application.
Supergene metal deposits form when deeply buried ore bodies are exposed at the Earth's surface and undergo oxidation, dissolution, and significant reconcentration of metals. This issue highlights some of the most recent advances in the field, including cutting-edge research in economic geology, paleoclimate and geoarcheology studies, environmental geochemistry, geobiology, and corrosion science.
December 2015 - Geomicrobiology and Microbial Geochemistry
Microbes exert significant geochemical and mineralogical control on local environments through their metabolic and growth needs. In turn, local geochemical conditions dictate what metabolic processes are possible. This thematic issue is focused on the interface between the Earth, environmental systems, and microbial life. The latest discoveries, theories, “omic” methods, and emerging frontiers in the area of geomicrobiology and microbial geochemistry are discussed.