DU An-dao

China Geological Survey

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Shaozhen Chen

Sun Yat-sen University

Zhang Ke-yao

China Earthquake Administration

Wenjun Qü

Ocean University of China

Xiaoqiu Zou

Guangzhou Liwan District Traditional Chinese Medicine Hospital

Yin Ningwan

Chinese Academy of Geological Sciences

Dezhong Sun

Yantai University

He Hongliao

Guangzhou Marine Geological Survey

Sun Yali

China Coal Technology and Engineering Group Corp (China)

Cooperative Institutions

Chinese Academy of Geological Sciences

Sun Yat-sen University

PLA Information Engineering University

The First Affiliated Hospital, Sun Yat-sen University

Tongji University

Guangdong Academy of Agricultural Sciences

Ministry of Agriculture and Rural Affairs

Key Laboratory of Guangdong Province

Guangdong University of Technology

Union Hospital

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Re-Os isotopic age dating of molybdenite separates from Elegen porphyry Mo (Cu) mineralized area, northwestern Alxa, western Inner Mongolia

Mineralium Deposita (2005)

DU An-dao

Molybdenite

Isochron dating

Radiometric dating

Porphyritic

Mineral Prospectivity

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Citations (11)

Preliminary results of Os isotopic ratios of osmium minerals from the Gaositai ultramafic complex

JUSTC (2007)

DU An-dao

Os isotopic compositions of an iso-osmiridium and a hex-osmiridium in the Gaositai ultramafic complex,Hebei province,were reported.The 187Os/188Os ratios for the two minerals are 0.123 582±7 and 0.123 731±7,respectively.The explanation of the data depends on other geological and geochemical constraints,such as the ages of the minerals and the characteristics of the source regions.Suppose the osmium was derived from a primitive upper mantle,the model ages of the two minerals could be 500±10 Ma;if the osmium was from an old depleted lithospheric mantle,the model ages could be as young as 60±15 Ma;while if the osmium was from fertile plume source,the model ages could be as old as 1 600±10 Ma.The model age of the minerals depends on the degrees of depletion or of enrichment of the mantle source.In contrast,if the minerals were formed in Yindo-sinian orogeny,Os could be likely derived from an old depleted lithosphric mantle and if the minerals were formed in the Mid-Proterozoic,Os were probably derived from a fertile plume source.Based on regional geology,we prefer that the Os was derived from a fertile source and the Gaositai intrusion was formed during the Mid-Proterozoic.However,the issue merits further investigation.Nevertheless,the data provided by this work will help with understanding the age of Gaositai platinum-bearing intrusion and the mantle characteristics beneath the northern margin of the North China Block in the future.

Osmium

Ultramafic rock

Mantle plume

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Research and Preliminary Application of Re-Os Isotope System for Limestone Samples

Rock and Mineral Analysis (2011)

DU An-dao

Sampling and digestion methods for Re-Os isotope analysis are improved for limestone samples.Hydrochloric acid was added to Carius tube to react with limestone in order to release CO2.Then the Carius tube was sealed after adding oxidant reagent and spikes.Re-Os isotope system of the limestone,hosted on the bottom of Jiushidao formation of the Permian stratum at Yushu,Qinghai Province,was firstly analyzed worldwide by using this method.The obtained accurate age of(283.1±7.1) Ma(MSWD=0.61,Model 1,n=7) is consistent with the geological setting of the Schwagerina bearing stratum and especially the age U-Pb zircon dates for magmatic rocks.187Os/188Os initial ratio obtained is 0.56±0.12,in agreement with the 187Os/188Os value of Permian seawater.Reasonable Re-Os isotopic age and initial Os value are obtained showing the closure of Re-Os isotope system in Limestone is perfect.Concentrations of Re and Os are positively correlated with organic carbon,which indicates Re and Os occur in the organic matter of limestone.This application provides a new tool for the stratigraphic classification and correlation.

Stratum

Isotope Geochemistry

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Sources of Ore-forming Metals in Kuroko-type Deposits: Evidence from the Re-Os and He Isotopes for the Uwamuki Kuroko Deposit of Japan

DU An-dao

Uwamuki Kuroko is the most typical kuroko-type deposit in Japan. It is located in the aborted island-arc rift zone formed in the Miocene epoch and is hosted in the felsic volcanic package within a bimodal (basalt-rhy-olite) sequence. The Uwamuki deposit consists of underlying pipe-like siliceous ore and layered massive black ore, showing vertical metal zoning from yellow ore upwards to black ore. In order to study the sources of ore-forming metals, which is a long debated and unsolved issue, Re-Os isotope and He isotope compositions of the ore and host rock were systematically analyzed. The rhyolites hosting the siliceous ore yield R/Ra ratios ranging from 0. 93 to 1. 14, suggesting that the felsic magma should be mainly formed by remelting of the continental crust. The massive black ores have relatively high 187Os/188Os ratios (2. 246 - 7. 608), showing the Os came from either crust-derived sediments or underlying basement rocks in the ore district. The stringer or stockwork siliceous ore and massive yellow ore as well as occasional black ore yield relatively low 187Os/188Os ratios (0. 432 -0. 793), indicating that the ore Os has two possible sources, i. e. mantle and continental crust, which contributed about 57%-89% of mantle Os and 11%-43% of crust Os to the Uwamuki deposit, respectively. A clear vertical rhythmic variation of 187Os/188Os ratios in the layered massive black ore has been observed, which suggests the periodically mixing among ore-forming fluids (metals) in various stages. Based on the fluid mixing and metal sources, a new two-stage model is proposed to illustrate ore-forming processes of the Uwamuki kuroko deposit.

Felsic

Stockwork

Ore genesis

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Citations (2)

Re-Os isotopic dating of molybdenite from the Chilu molybdenum deposit in Fu'an,Fujian Province

Zhongguo dizhi (2009)

Zhang Ke-yao DU An-dao

At present,Re-Os isotopic dating of molybdenite is one of the direct ways to acquire the ore-forming age.Using TJA X-series ICP-MS,the authors dated five molybdenite samples collected from the Chilu molybdenum deposit and obtained model ages.The results show that the ore-forming age is about 105-106 Ma, quite close to the emplacement age of porphyritoid granite,adamellite and feldspar graphic granite(115±4 Ma, Rb-Sr isochron age),which are intimately related to the ore-forming processes in this area.This indicates that they are all products of late Yanshanian magmatism.The above outcome provides direct evidence not only for the research of late Yanshanian magmatism and mineralization in the Pucheng-Ningde NW-trending ore belt but also for the comparative study between the Pucheng-Ningde ore-forming belt and the Shanhang-Yuenxiao ore-forming belt,thus contributing to mineral exploration in these two belts.

Molybdenite

Radiometric dating

Sericite

Mineral resource classification

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Citations (8)

Re-Os isotopic dating of molybdenite from Datongchang copper-lead-zinc deposit in Tengchong area, western Yunnan

Mineralium Deposita (2005)

DU An-dao

Molybdenite

Radiometric dating

Stockwork

Polymetallic replacement deposit

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Citations (12)

A Study of the Rhenium‐Osmium Geochronometry of Molybdenites¹

Acta Geologica Sinica - English Edition (1995)

DU An-dao He Hongliao Yin Ningwan Xiaoqiu Zou Sun Yali

Abstract This study deals with the first application of the isotope dilution‐inductively coupled plasma mass spectrometry in the rhenium‐osmium geochronometry in China. The chemical separation procedure included decomposition of samples by means of alkali fusion, extraction of rhenium by acetone and extraction of osmium by distillation. The recovery of both elements in the entire process was more than 90% . The blanks of analyses were 0.07 ng for rhenium and 0.01 ng for <sup>187</sup>Os. The mineralization ages of molybdenites from four molybdenum deposits in China were determined by using this method, with a precision (2σ) of about ±3% . These results agree satisfactorily with their geological backgrounds. The Re‐Os method can directly determine ages of metal deposits and reflect the true ages more reliably than other dating methods that only determine the ages of country rocks from which mineralization ages are inferred. As many hydrothermal sulphide deposits usually contain molybdenites, this method has bright prospects of wide application.

Osmium

Molybdenite

Isotope dilution

10.1111/j.1755-6724.1995.mp8002004.x

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Citations (76)