Impact of mining on sedimentation: The Camel and Gannet estuaries, Cornwall

D Pirrie*, M. R. Power, A Payne, G. S. Camm, PD Wheeler

*Awdur cyfatebol y gwaith hwn

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddCyfraniad i gynhadleddadolygiad gan gymheiriaid

    Crynodeb

    The mineralogy and geochemistry of the inter-tidal sediments in the Camel and Gannet estuaries on the north Cornwall coast has been examined to test the importance of mining on sediment supply. In the Camel Estuary there is a clear stratigraphical geochemical anomaly for Sri, Wand Zr which corresponds with abundant cassiterite, wolframite and zircon. This sediment was supplied to the estuary as a result of the release of mine waste tailings from hard rock mining of main stage mineralisation, probably from mines such as Mulberry and Wheal Prosper in the area around Lanivet. In contrast the sediments in the Gannet Estuary contain very high concentrations of Pb and Zn. In one core, maximum Pb concentrations are in excess of 8500 ppm, along with over 1600 ppm Zn. This same stratigraphical interval also has very significant enrichment in Zr, Ce, La and Y along with high values for Ag. The geochemistry of the Gannet Estuary sediments is reflected by the mineralogy with abundant galena, sphalerite and plumbogummite (Pb-P-Al phase). In addition to these detrital grains there are abundant diagenetic phases precipitated within the sediments, including authigenic Pb, Zn and Cu-Fe minerals, Early diagenetic calcite-siderite-Fe monosulphide concretions are also present. The likely source for this Pb-Zn-Ag mine waste is from the area around Newlyn Downs. In both cases, the release of particulate mine waste, possibly following mine closure in the latter part of the 19th century or early 20th century, had a significant impact on down stream estuarine, sedimentation. However, in the Camel Estuary the presence of abundant cassiterite is unlikely to have had a significant impact on the biosphere. whilst in the Gannet Estuary the presence of significant Ph and Zn and the mineralogical evidence that there is diagenetic mobility of Ph, Zn and Cu, is indicative that these elements were, and may still be, bioavailable.

    Iaith wreiddiolSaesneg
    TeitlGEOSCIENCE IN SOUTH-WEST ENGLAND
    GolygyddionCL Williams
    CyhoeddwrUSSHER SOC
    Tudalennau21-28
    Nifer y tudalennau8
    CyfrolVOL 10, PT 1
    StatwsCyhoeddwyd - 2000
    Digwyddiad38th Ussher-Society Conference - Torquay, Y Deyrnas Unedig
    Hyd: 5 Jan 20008 Jan 2000

    Cyfres gyhoeddiadau

    EnwProceedings of the Ussher Society
    CyhoeddwrUSSHER SOC
    Cyfrol10
    ISSN (Argraffiad)0566-3954

    Cynhadledd

    Cynhadledd38th Ussher-Society Conference
    Gwlad/TiriogaethY Deyrnas Unedig
    DinasTorquay
    Cyfnod5/01/008/01/00

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