The high mass resolution of SHRIMP IIe is achieved by the use of double-focussing mass spectrometer (simultaneous energy and mass refocussing) with a very large turning radius of Magnet and Electrostatic Analyser.SHRIMP has many applications: zircon dating in copper-uranium-gold-silver deposits, uranium-lead dating of sulphur in the sulphide minerals that form metal ores, the isotopic composition of sulphur in the giant base metal ore bodies.In contrast, destructive techniques such as LA-ICP-MS consume a large volume, leave a deep crater in the target grain, and often sample heterogeneous domains that are not visible and thus often yield discordant results which are difficult to interpret.
Compared with the gneissic granodiorite, the gneissic quartz diorite has higher ΣREE contents and lower Eu/Eu* and (La/Yb) (2.5 Ga) values and Hf crustal model ages ranging from 0 to 5 and 2.7 to 2.9 Ga, respectively.
Therefore, ∼2.5 Ga magmatic and Paleoproterozoic metasedimentary rocks and late Neoarchean to early Paleoproterozoic and late Paleoproterozoic tectono-thermal events have been identified in the basement beneath the CHB.
The SHRIMP is primarily used for geological and geochemical applications.
It can measure the isotopic and elemental abundances in minerals at a 30 micrometre-scale and is therefore well-suited for the analysis of complex minerals, as often found in metamorphic terrains, some igneous rocks, and for relatively rapid analysis of statistical valid sets of detrital minerals from sedimentary rocks.
This technique has proved reliable in dating relatively simple magmatic rocks with homogeneous zircon populations and has proved most effective in the dating of detrital zircon grains where high precision is not required.