Hydrothermal technology for nanotechnology

This handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures emphasizes terrestrial impact structures, field geology, and particularly the recognition and petrographic study of shock-metamorphic effects in terrestrial rocks. Individual chapters include: 1) Landscapes with Craters: Meteorite Impacts, Earth, and the Solar System; 2) Target Earth: Present, Past and Future; 3) Formation of Impact Craters; 4) Shock-Metamorphic Effects in Rocks and Minerals; 5) Shock-Metamorphosed Rocks (Impactities) in Impact Structures; 6) Impact Melts; 7) How to Find Impact Structures; and 8) What Next? Current Problems and Future Investigations.

/pdf/traces-of-catastrophe-a-handbook-of-shock-metamorphic-28xgtwpf9g.pdf

Traces of Catastrophe: A Handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures

Fragments of the Earth’s mantle are frequently transported to the surface via volcanic rocks that are dominantly alkaline in nature. These fragments range up to sizes in excess of 1 m across. The term “mantle xenoliths” or “mantle nodules” is applied to all rock and mineral inclusions of presumed mantle derivation that are found within host rocks of volcanic origin. The purpose of this contribution is to review the geochemistry of mantle xenoliths.

Mantle Samples Included in Volcanic Rocks: Xenoliths and Diamonds

The origin of cratonic diamonds — Constraints from mineral inclusions

### Introduction

Earth’s carbon, derived from planetesimals in the 1 AU region during accretion of the Solar System, still retains similarities to carbon found in meteorites (Marty et al. 2013) even after 4.57 billion years of geological processing. The range in isotopic composition of carbon on Earth versus meteorites is nearly identical and, for both, diamond is a common, if volumetrically minor, carbon mineral (Haggerty 1999). Diamond is one of the three native carbon minerals on Earth (the other two being graphite and lonsdaleite). It can crystallize throughout the mantle below about 150 km and can occur metastably in the crust. Diamond is a rare mineral, occurring at the part-per-billion level even within the most diamondiferous volcanic host rock although some rare eclogites have been known to contain 10–15% diamond. As a trace mineral it is unevenly distributed and, except for occurrences in metamorphosed crustal rocks, it is a xenocrystic phase within the series of volcanic rocks (kimberlites, lamproites, ultramafic lamprohyres), which bring it to the surface and host it. The occurrence of diamond on Earth’s surface results from its unique resistance to alteration/dissolution and the sometimes accidental circumstances of its sampling by the volcanic host rock. Diamonds are usually the chief minerals left from their depth of formation, because intact diamondiferous mantle xenoliths are rare.

Diamond has been intensively studied over the last 40 years to provide extraordinary information on our planet’s interior. For example, from the study of its inclusions, diamond is recognized as the only material sampling the “very deep” mantle to depths exceeding 800 km (Harte et al. 1999; McCammon 2001; Stachel and Harris 2009; Harte 2010) although most crystals (~95%) derive from shallower depths (150 to 250 km). Diamonds are less useful in determining carbon fluxes on Earth because they provide only a small, …

Diamonds and the Geology of Mantle Carbon

Hydrous and carbonatitic mantle fluids in fibrous diamonds from Jwaneng, Botswana

High-Mg carbonatitic microinclusions in some Yakutian diamonds-a new type of diamond-forming fluid

CARBON and hydrogen are only trace constituents of the Earth's mantle, yet carbon- and hydrogen-bearing fluids have an important effect on magma genesis, mantle rheology and mantle chemistry. Many mantle-derived rocks record interactions with such fluids, but direct samples of the fluids themselves are rare. Diamonds, owing to their robust nature, constitute effective sampling devices for such deep-seated fluids1; for example, carbonates and water have been found2,3 in fluid inclusions in fibrous diamonds4. In addition, CO2, H2O, CO, CH4, H2 and N2 have been detected in gases released from diamonds by crushing5 or heating6,7, but their primary nature could not be confirmed beyond doubt1. Here we report the discovery of solid CO2 in a natural diamond. Infrared spectroscopy indicates that the CO2 is presently at a pressure of 5 GPa (50 kbar), and must therefore have been trapped at even greater pressures in the hot mantle, corresponding to depths of about 220–270 km. At these pressures, free CO2 should react with olivine and pyroxene; thus, its survival indicates the presence at depth of an environment of different mineralogy such as a fully carbonated metasomatic vein, or a block of subducted sediments.

Solid carbon dioxide in a natural diamond

Trace element analyses of fluid-bearing diamonds from Jwaneng, Botswana

Diamonds were found in impact melt rocks and breccias at the Popigai impact structure in Siberia. The diamonds preserve the crystallographic habit and twinning of graphites in the preimpact target rocks, from which they formed by shock transformation. Secondary and transmission electron microscopy indicate that the samples are polycrystalline and contain abundant very thin lamellae, which could represent stacking faults, with local hexagonal symmetry, or microtwins. Microcrystalline units are ≤1 µm. Infrared spectroscopy indicates the presence of solid CO 2 and water in microinclusions in the diamonds, CO 2 being under a pressure greater than 5 GPa (at room temperature). Trace element and isotopic compositions confirm the derivation from graphite precursors.

Marcus Schrauder

Papers

Hydrous and carbonatitic mantle fluids in fibrous diamonds from Jwaneng, Botswana

High-Mg carbonatitic microinclusions in some Yakutian diamonds-a new type of diamond-forming fluid

Solid carbon dioxide in a natural diamond

Trace element analyses of fluid-bearing diamonds from Jwaneng, Botswana

Diamonds from the Popigai impact structure, Russia