首页|A bulk annealing and dissolution-based zircon concentration method for mafic rocks
A bulk annealing and dissolution-based zircon concentration method for mafic rocks
扫码查看
点击上方二维码区域，可以放大扫码查看
原文链接
NSTL
Elsevier
Zircon geochronology is applied to a variety of geological problems to precisely and accurately date rocks via U-Pb decay. Zircon is most abundant and easily recovered in intermediate to felsic rocks, including the silicic eruptives of bimodal large igneous provinces, or fractionated granophyres in mafic-ultramafic complexes. However, the concentration of zircon crystals by conventional density and magnetic separation methods is inefficient and/or ineffective for medium- to fine-grained mafic rocks, due to their rarity, small grain size, common association with ferromagnetic minerals, and/or occlusion by paramagnetic modal minerals. To address these shortcomings, we have developed and tested a zircon concentration method that is based on a combination of physical separation and chemical dissolution. The sample is initially ground to sand-size particles and heavy minerals concentrated via density on a water table. The heavy mineral-rich fraction is annealed by heating at 900 degrees C for 60 h, and then put through a series of acid digestions: aqua-regia, hydrofluoric acid, aqua-regia and finally hydrochloric acid. This new method allows the concentration of an almost pure zircon aliquot, since zircon is one of just a few minerals that can survive this bulk rock acid attack. The result is an efficient extraction of analytically viable amounts of zircon for U-Pb geochronology using tens of grams of rock sample, representing an increase up to a hundred times the recovery rates of conventional separation techniques for zircon concentration.
NSTL
Elsevier
