Guizhou province is an very important area for epithermal type Hg,Sb and Au deposits in China.All along,there is considerable controversy about the mineralization age.In this study,Sm-Nd isotopic isochron age measurements were performed on the fluorites and calcites collected from the Dachang Sb deposit,the Zimudang Au deposit,and the Luanyantang Hg deposit.The results show that the fluorites and calcites from the Dachang Sb deposit were formed in Late Jurassic with the Sm-Nd isochron age measured as 148±13 Ma and 142.3±7.9 Ma,with neodymium initial values of 0.512256 and 0.512151 respectively.The Sm-Nd isochron age of the calcites from the Zimudang Au deposit is 250±14 Ma,a transition between Late Permian and Early Triassic,and its neodymium initial value is 0.511909.The Sm-Nd isochron age of the calcites from the Luanyantang Hg deposit is 364±24 Ma,which was formed in the Late Devonian,and the neodymium initial value is 0.511517.Combined with the previous studies,we infer that the mineralization of Hg,Sb and Au are not all formed in one period only(i.e.the Yanshanian),but experienced a complex process from Caledonian to Hercynian-Indosinian,to early Yanshanian and late Yanshanian.Thus,they formed an epithermal-type mineralization pedigree with a long history of evolution.
Rb is an important rare metal element used widely in industry.Placer Sn was explored in the Xiaojiang region in Guidong,Hunan in 1958,but no follow-up work has been reported.Samples were collected from the fine-grained two-mica granite,the biotite porphyritic granite,and the coarse grained biotite granite in the Xiaojiang ore field.The petrochemical features of the samples show that the three types of granites were likely originated from the same granitic magma.Due to fractional crystallization of the granitic magma,the latest fine-grained two-mica granite is enriched in rare metals and Y with tetrad REE pattern.For example,in the two-mica granite,Rb2O(0.10%),Nb2O5(0.005%),and Y2O3(0.01%) contents are beyond or around the cutoff grades.The EMPA analysis shows that Rb is enriched in K-feldspar and biotite,while Y is enriched in fluorite.In the end,the reserves of Rb2O is estimated to be about 320,000 tons assuming the Rb mineralization depth of the Xiaojiang granite is 50 m,and granite has a promising perspective for pegmatite type rare metal deposit and ion adsorption type REE deposit as well.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
'/%3e%3c/defs%3e%3cpath fill='%23012169' d='M0 0h10080v5040H0z'/%3e%3cpath stroke='%23fff' stroke-width='.6' d='m0 0 6 3m0-3L0 3' clip-path='url(%23b)' transform='scale(840)'/%3e%3cpath stroke='%23e4002b' stroke-width='.4' d='m0 0 6 3m0-3L0 3' clip-path='url(%23c)' transform='scale(840)'/%3e%3cpath stroke='%23fff' stroke-width='840' d='M2520 0v2520M0 1260h5040'/%3e%3cpath stroke='%23e4002b' stroke-width='504' d='M2520 0v2520M0 1260h5040'/%3e%3cg fill='%23fff'%3e%3cuse xlink:href='%23d' x='2520' y='3780'/%3e%3cuse xlink:href='%23a' x='7560' y='4200'/%3e%3cuse xlink:href='%23a' x='6300' y='2205'/%3e%3cuse xlink:href='%23a' x='7560' y='840'/%3e%3cuse xlink:href='%23a' x='8680' y='1869'/%3e%3cuse xlink:href='%23e' x='8064' y='2730'/%3e%3c/g%3e%3c/svg%3e)