1. BASELINE GEOCHEMISTRY
OF DEVONIAN AND
CARBONIFEROUS
METASEDIMENTARY
ROCKS IN CORNWALL
N.G. LeBoutillier, P.W. Scott,
R.K.Shail and R.C. Scrivener

2. •468 samples of metasedimentary rock were taken from a variety
of coastal, inland, quarry and temporary exposures across
Cornwall.
•Samples had to be free of any visible effects of weathering
and/or mineralisation of any kind.
•The samples were crushed and milled to a fine powder and
shipped to Vancouver where they were analysed by ICP-MS,
following a four-acid digest, for a suite of 40 elements (+ gold).
•The resulting database holds over 19,000 records and in
conjunction with its associated GIS, geographical and geological
databases, forms an important resource which has applications
across a wide variety of fields.

3. Original map courtesy of Dr Brian Leveridge (unpublished)

4. THE PROJECT DATABASE HOLDS A TOTAL OF 468 METASEDIMENT
SAMPLE RECORDS.
OF THESE:-
• 279 ARE FROM THE GRAMSCATHO BASIN
• 74 ARE FROM THE LOOE BASIN
• 67 ARE FROM THE SOUTH DEVON BASIN
• 35 ARE FROM THE TAVY BASIN
• 13 ARE FROM THE CULM BASIN
THESE METASEDIMENTS HAVE BEEN BROADLY CLASSIFIED BY
LITHOLOGY INTO MUDSTONES, SILTSTONES AND SANDSTONES.
THE DATABASE HOLDS THE RECORDS OF:-
• 285 MUDSTONES
• 48 SILTSTONES
• 135 SANDSTONES

6. Mo_ppm Cu_ppm Pb_ppm Zn_ppm Ag_ppm Ni_ppm Co_ppm Mn_ppm Fe_% As_ppm
AVER 0.51 32 19 106 0.1 53 24 871 4.74 23
MEDIAN 0.4 26.2 13.6 98 0.1 53.9 23 670.5 4.82 14
MODE 0.2 22.2 13.7 97 0.1 29.9 24 665 4.72 7
ST DEV 0.5 24 23 50 0.1 21 10 702 1.39 25
U_ppm Th_ppm Sr_ppm Cd_ppm Sb_ppm Bi_ppm V_ppm Ca_% P_% La_ppm
AVER 2 8 88 0.13 1.5 0.27 124 0.44 0.05 24
MEDIAN 2.3 8.1 73 0.1 0.9 0.2 130 0.15 0.056 23.55
MODE 2.3 7.6 52 0.1 0.5 0.1 147 0.04 0.056 20.3
ST DEV 0.64 3 57 0.12 2 0.21 40 0.86 0.03 10
Cr_ppm Mg_% Ba_ppm Ti_% Al_% Na_% K_% W_ppm Zr_ppm Ce_ppm
AVER 97 1.28 434 0.35 7.97 0.99 2.49 37 90 52
MEDIAN 98.5 1.23 438 0.32 7.92 0.64 2.65 26.1 93.6 51
MODE 124 1.32 463 0.27 6.19 0.47 2.19 0.6 113.3 48
ST DEV 33 0.52 175 0.14 2.01 0.88 1.08 37 27 20
Sn_ppm Y_ppm Nb_ppm Ta_ppm Be_ppm Sc_ppm Li_ppm S_% Rb_ppm Hf_ppm
AVER 4 12 8 0.59 2 13 109 0.09 111 3
MEDIAN 2.8 10.6 7.1 0.5 2 13 99.9 0.05 102.5 3.1
MODE 2.9 9.5 5.7 0.5 3 11 53.2 0.05 61 3.5
ST DEV 6 6 4 0.24 1 4 59 0.08 55 0.85

33. •Analysis of the data to date has yielded important information on
the background chemistry of the metasediments in Cornwall.
•It has direct application to the study of metasediment mineralogy
and provenance.
•It can be used to characterise particular formations as an aid to
‘geochemical mapping’.
•It is an important resource for those studying metal transport
within the soil and into the biosphere.
•It is an important resource for those bodies dealing with
hydrological modelling and the definition of what constitutes
pollution.

34. Acknowledgements:
•Funding from the European Social Fund (Project No:
011019SW1).
•Dr Brian Leveridge.
•BGS Keyworth
•Mr Steve Pendray (Camborne School of Mines).