Pb 210 dating sediments
This is overlain by the Mines Subgroup dolostones and shales, including a number of reduced units near the base.
The uppermost of the three Roan Group units in the DRC is the Dipeta Subgroup, comprising a lower regressive suite, including oxidised, evaporitic rocks, followed by transgressive carbonate rocks with some reduced intervals.
A period of extension commenced after ~900 Ma, and in Zambia, the sedimentary sequence began after 880 Ma, with the Lower Roan Subgroup oxidised rift facies clastic rocks, deposited in a series of restricted sub-basins controlled by extensional normal faults, including the thin reduced argillites of the Copperbelt Orebody Member near the middle of the unit.
The succeeding sag phase Upper Roan Subgroup, is dominantly made up platformal mixed carbonate and clastic rocks, but also included a 500 m) evaporite/salt bed deposited in a restricted sub-basin, separated from the open sea by a stromatolitic reef.
The most important for the purposes of radiation protection are the radionuclides in the U-238 and Th-232 decay series.
For most human activities involving minerals and raw materials, the levels of exposure to these radionuclides are not significantly greater than normal background levels and are not of concern for radiation protection.
It closely coincides with the southern half of a complex, arcuate structural zone, the late Neoproterozoic to early Cambrian Lufilian Arc.
Although part of the same curvilinear trend, the Zambian Copperbelt deposits, are hosted by non-evaporitic, rift facies siliciclastic rocks that are not temporally or lithologically equivalent to the mainly carbonate hosts of the Congolese Copperbelt.
digitizing tablet, and a 54-inch wide-format plotter.
During deposition of the late Upper Roan and Dipeta subgroups, a period of 'renewed extension' commenced, reflected by a ~30 to 100 km wide by ~500 km long corridor of gabbroic and lesser felsic intrusions, and an associated volcanic belt of thin mafic lavas and tuffs emplaced from ~765 to 735 Ma.
All minerals and raw materials contain radionuclides of natural origin.
In conjunction with the Geosciences Advisory Unit at the National Oceanography Centre in Southampton we are able to offer this relatively new technique for precisely dating very recent sediments.
This is particularly applicable in dating sediment accumulation rates for geohazard analysis in subsea engineering projects.
In addition, the structural architecture in Zambia is characterised by thrusted Palaeo- to Mesoproterozoic metamorphic basement inliers and folded Neoproterozoic sedimentary host rocks, in contrast to the thin skinned deformation of the hosts in the DRC, without involvement of basement.