Monday, 16 September 2013

The TW:eed core arrives in Keyworth... by Andrea Snelling

 
Professor Sarah Davies, Dr Andrea Snelling and
Dr Carys Bennett examining the Tweed Basin core
Andrea Snelling has just joined the TW:eed team. Her speciality within TW:eed is to use stable isotope composition of the rocks to help interpret palaeoenvironment around the time of tetrapod evolution. Here she tells us a little about her first glimpse of the core material through the early Carboniferous collected earlier this year.


The 501m of fluvial and coastal plain
sedimentary rocks from the Early
Carboniferous of the Tweed Basin
The TW:eed project members met last week at the BGS National Core Repository, to get the first glimpse of the 501 metre core collected from near Berwick-upon-Tweed, Northumberland. The core, which represents millions of years of rock record through the Ballagan Formation offers the chance for us to investigate environmental change through a crucial period of time when fully land-based vertebrates were evolving during the Early Carboniferous (from about 359 Ma onwards).

The core was laid out in its entirety in the BGS core store, so members of the team were able to see for the first time an almost complete record of the Early Carboniferous sedimentary succession, spanning 15 million years. The core is made up of three main lithologies: sandstones, mudstones and siltstones with occasional layers of gypsum/anhydrite and dolomite. With the whole core laid out we were able to see the intricate detail of the different rock types, the transitions between them and how they changed through time. It was easy to get lost in the fascinating sedimentary features, including evidence of ripples, fossils soils and burrowing, and not forgetting the fossil remains lurking within the sediment.

Gypsum and anhydrite formed in a
palaeo-sabkha in the Tweed Basin
Over the next month Carys Bennett (team Tw:eed sedimentologist and micropalaeonotologist) and Tim Kearsey (sedimentologist and statigrapher) have the monumental task of logging the core in fine detail, making sense of the transitions and deciphering the sedimentary structures, whilst Emma Reeves (University of Southampton) and I will follow closely behind taking samples for palynology, isotope analysis, thin sections (to examine the really fine detail of the sedimentary rocks) and recovering any fossil fragments that may be apparent. Together we hope to be able to reconstruct the environment at a crucial time in Earth’s history when tetrapods first emerged from the ocean onto land.

Andrea Snelling 

No comments: