Tim Tomkinson

University of Glasgow | UofG · Scottish Universities Environmental Research Centre (SUERC)

Northwest Africa (NWA) 5790 is the most recently discovered member of the nakhlite group. Its mineralogy differs from the other nakhlites with a high abundance mesostasis (38.1 ± 3.6 vol%) and scarcity of olivine (4.0 ± 2.2 vol%). Furthermore, zoning of augite phenocrysts, and other petrographic and chemical characteristics suggest that NWA 5790 sa...

The Lafayette meteorite is an olivine clinopyroxenite that crystallized on Mars ∼1300 million years ago within a lava flow or shallow sill. Liquid water entered this igneous rock ∼700 million years later to produce a suite of secondary minerals, collectively called ‘iddingsite’, that occur as veins within grains of augite and olivine. The deuterium...

The three dimensional structure of the Nakhla meteorite has been investigated in order to provide a detailed picture of the fluid pathways in the volcanic subsurface of Mars. A combination of computed tomography and electron microscopy have been used to identify, characterise and interpret the distribution, size, interconnectivity and secondary min...

Veins containing carbonates, hydrous silicates, and sulfates that occur within and between grains of augite and olivine in the Nakhla meteorite are good evidence for the former presence of liquid water in the Martian crust. Aqueous solutions gained access to grain interiors via narrow fractures, and those fractures within olivine whose walls were o...

Carbonation is the water-mediated replacement of silicate minerals, such as olivine, by carbonate, and is commonplace in the Earth's crust. This reaction can remove significant quantities of CO2 from the atmosphere and store it over geological timescales. Here we present the first direct evidence for CO2 sequestration and storage on Mars by mineral...

The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentini...

The nakhlite meteorites are clinopyroxenites that are derived from a ~1300 million year old sill or lava flow on Mars. Most members of the group contain veins of iddingsite whose main component is a fine-grained and hydrous Fe- and Mg-rich silicate. Siderite is present in the majority of veins, where it straddles or cross-cuts the Fe-Mg silicate. T...

Introduction: The pyroxene dominated matrix of the ALH84001 meteorite contains both plagioclase glass and various carbonates [1]. The carbonates can be divided into three types: Mg-Fe-Ca zoned discs, carbonate globules within plagioclase glass and irregular carbonates in crush zones [2]. Here we have sought to understand better the mode of carbonat...

Introduction: The pyroxene dominated matrix of the ALH84001 meteorite contains both plagioclase glass and various carbonates [1]. The carbonates can be divided into three types: Mg-Fe-Ca zoned discs, carbonate globules within plagioclase glass and irregular carbonates in crush zones [2]. Here we have sought to understand better the mode of carbonat...

Petrographic analysis of eight CM carbonaceous chondrites (EET 96029, LAP 031166, LON 94101, MET 01072, Murchison, Murray, SCO 06043, QUE 93005) by electron imaging and diffraction, and X-ray computed tomography, reveals that six of them have a petrofabric defined by shock flattened chondrules. With the exception of Murchison, those CMs that have a...

The three dimensional structure of the Nakhla meteorite has been investigated in order to provide a detailed picture of the fluid pathways in the volcanic subsurface of Mars. A combination of computed tomography and electron microscopy have been used to identify, characterise and interpret the distribution, size, interconnectivity and secondary min...

NanoSIMS measurements record δD values up to +4725‰ in Lafayette which reveal martian waters of crustal origin are incorporated into the smectite and adjacent olivine.

Veins of clay and carbonate in the nakhlite meteorite Lafayette formed by dissolution and replacement of olivine.

A petrographic and δD investigation of the Yamato nakhlites (000593, 000749) confirm a martian origin of the secondary mineral veins and multiple fluid generations.

We have designed and built a compact breadboard prototype instrument called WatSen: a combined ATR mid-IR spectrometer, fixed-focus microscope, and humidity sensor. The instrument package is enclosed in a rugged cylindrical casing only 26 mm in diameter. The functionality, reliability and performance of the instrument was tested in an environment c...

Etch pits within olivine grains from the nakhlite meteorites reveal the magnitude and timescale of water-mediated alteration of the martian crust.

Evidence from the Lafayette meteorite shows that carbon dioxide could have been sequestered very effectively from the martian atmosphere by mineral carbonation.

Veins containing carbonates, hydrous silicates, and sulfates that occur within and between grains of augite and olivine in the Nakhla meteorite are good evidence for the former presence of liquid water in the Martian crust. Aqueous solutions gained access to grain interiors via narrow fractures, and those fractures within olivine whose walls were o...

Secondary minerals in the Nakhla meteorite crystallized in pores formed by etching of olivine, and dissolution was enhanced by shock-formed fractures and dislocations.

The hot desert nakhlite find NWA 5790 is encrusted by terrestrial carbonates and microbial filaments.

We have sought to understand the mechanisms of deformation in the Murchison parent body by combining two techniques: calcite e-twin stress analysis and high resolution X-ray computed tomography.

Introduction: There is now a wealth of data ac-quired from spacecraft in orbit around Mars, comple-mented by results from in situ instrumentation carried by the Spirit and Opportunity rovers, as well as the Phoenix lander. Results from these missions have built up a picture of the distribution of different mineral phases across Mars' surface, and h...

The nakhlite meteorites contain minerals including clays, salts and carbonates that crystallized from water within an impact-induced hydrothermal system or subsurface aquifer [1,2]. These minerals can be used to explore the longevity, scale and evolution of the aqueous system. However, such work has proven to be challenging owing to their very fine...

The CM carbonaceous chondrites contain abundant evidence for low temperature aqueous alteration in the form of minerals including calcium, magnesium, iron and manganese bearing carbonates and magnesium-iron phyllosilicates. The chronology of carbonate mineralization can be determined using the Mn-Cr system and results reveal crystallization ages ra...

The Thermo Scientific HELIX-platform Split Flight Tube (HELIX-SFT) noble gas mass spectrometer is specifically designed for simultaneous collection of helium isotopes. The high mass spur houses a switchable 1011 - 1012 Ω resistor Faraday cup and the low mass spur a digital pulse-counting secondary electron multiplier (SEM). We have acquired the HEL...

A combined 3D computed tomography and high resolution electron microscopy study of secondary minerals in the Nakhla meteorite, focusing on the formtation of halite.

The nakhlite meteorites contain mineral phases formed by aqueous processes. This study aims to combine isotopic analyses with three dimensional characterisation of the complex network of alteration veins.

Determining the carbon isotopic composition of ALH 84001 rosettes with NanoSIMS.

Detection of water and magnesite with WATSEN: the next generation of instrumentation for Mars.

Introduction: Prior to material being brought back directly from Mars by a sample return mission, Martian meteorites provide the best source for analysis of the fine-scale mineralogy of the Martian surface. The origins of ALH 84001 carbonates are of great importance for understanding the ancient Martian environment. Thought to have formed ~3.9 Ga [...

Clay minerals, known to be present both in martian meteorites and on the surface of Mars, contain unique information about the planet's climate history. Analyses of terrestrial analogues and clay minerals in nakhlite meteorites are underway.

Introduction: Martian meteorites provide an insight into the lithosphere, atmosphere and, potentially, the hydrosphere of Mars. It is hence important that these samples are studied to help us determine the environment in which they were produced. Water reacts with soluble salts on Mars; temperature changes then allow precipitation of evaporites suc...

Introduction: Over the past few decades Mars has been investigated directly by means of numerous surface and orbital instruments. Despite various indications of its presence on the surface, no direct detection of water has been made. Satellite imagery from orbit show many features such as valleys and channels that indicate mass outflows of liquid a...

Clays, salts, carbonates and Fe-rich silicates fill fractures within the martian nakhlite meteorites [1-3]. They have been interpreted to be the products of an ancient aqueous alteration related to an impact-induced hydrothermal system or sustainable subsurface brine [3, 4]. The poor crystallinity of the silicates suggests a short formation timesca...