Blaven Mountain

Impact Ejecta Layer At The Base Of Lavas On Skye Contains Unmelted Impactor Fragments.

In a collaboration between five institutions led by the UCL-Birkbeck Institute of Earth and Planetary Sciences*, geologists have discovered a 0.9-metre thick ejecta layer at the base of the Mid-Paleocene lava series, overlying Mesozoic sedimentary rocks at two localities on the Isle of Skye. The layer contains shocked minerals, metals, glasses and a variety of shocked rocks including basement gneiss, with lapilli and glass shards sharing several textural similarities with volcanic ignimbrites.
Metallic iron forms spherules with ferro-silicate glass, and irregular native iron grains with oxidized rims and barringerite (Fe,Ni2P). Rare carbo-nitrides and nitride minerals like osbornite with vanadium (TiVN) are interpreted as unmelted impactor remnants.

2017-12-Research Highlight

Research Highlights

In November this year Andrew Thomson and John Brodholt visited the European Synchrotron facility in Grenoble (ESRF) to measure the seismic properties of CaSiO3 perovskite at high pressures and temperatures. Although CaSiO3 perovskite only makes up about 5% of the lower mantle as a whole, it makes up as much as 30% of subducting oceanic crust.
We hope, therefore, to be able to use our measured velocities to trace subducted crust into the lower mantle and understand what happens to old ocean crust in the deep Earth. For instance, does oceanic crust just get smeared out and mixed back into the rest of the mantle, or could it separate out and form distinct reservoirs in the mantle? More...

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Precambrian Research Group

The Precambrian is the informal name for the first 90% of Earth history during which life began its incredibly long journey towards biological complexity. 

This journey culminated in the appearance and diversification of animals between about 750 and 540 million years ago. Sedimentary rocks become increasingly scarce the further back in time one looks. For this reason, Precambrian studies are multidisciplinary by necessity, piecing together clues from a range of fields: geochemistry, palaeobiology, biochemistry, sedimentology, genetics and a range of earth system models (atmospheric, ocean circulation, climate and biogeochemical).

Our research group primarily uses the chemical, mineral and isotopic composition of sedimentary rocks to reconstruct earth system evolution during the two billion year interval from the end of the Archaean Eon (about 2500 million years ago) to the beginning of the Phanerozoic Eon (about 540 million years ago). During this Proterozoic Eon, extraordinary perturbations occurred to our planet’s surface environment. Some disturbances were extreme but transient, such as the ‘Snowball Earth’ intervals of global glaciation. Others caused irreversible changes that shaped the modern earth system, such as the ‘Great Oxidation Event’ and the ‘Neoproterozoic Oxygenation Event’ without which we would not be here today.