Spectroscopy Charateristic Of Channel Water And Origin Tracing Of Dayakou Emerald From Yunan Province

Emerald samples from Dayakou occurrence?Malipo,Yunan,China?were investigated by gemological methods,polarized microscope,X-ray fluorescence spectroscopy,electron microprobe,LA-ICP-MS,infrared micro-spectroscopy and laser Raman spectroscopy in this dissertation.Main and trace elements analysis was used to determine the origin characteristics,analyze the origin of the color zonation,and trace the source of the parent fluid.Spectroscopy characteristics of the channel water were conducted to determine the coordination of type II water and its infrared absorption.The results show that the Dayakou emerald is a typical vanadium-dominant emerald which characterized by high Li and Cs content and the enrichment of W,Sn,As,Bi.The Cs content?avg.1754 ppm?is currently the highest among the world's emeralds.The contents of Rb and Cs show a clear linear relationship:Cs=389.2+59.34×Rb.For the first time,the Jos?Nigeria?,Panjshir Valley?Afghanistan?,and Poona?Australia?deposits are defined as partially V-dominant emerald deposits.A series of plots,such as Rb vs.Cs,V vs.V/Cr,LILE vs.CTE,and Li vs.Sc,are constructed to discriminate the provenance of V-dominant emeralds.The composition analysis shows that the origin of the color zonation in Dayakou emerald is related to the multi-stage mineralization of the deposit:1)The light green and white emerald core crystallized at the end of the pegmatite differentiation stage.2)The green emerald rim crystallized in the greisen stage.The increase of F and Cl ions in the higher salinity mineralization fluids in the late greisen stage led to an increase of V.Geochemical data indicate that the granite related to the Dayakou emerald metallization may be a hidden granite intrusion,which was formed in the same magmatic event as the Laojunshan granite,but was earlier and less evolved.Spectroscopic analysis shows that there are three types of coordination of type II water in Dayakou emerald:1)Type IId water molecule?H₂O-Na⁺-H₂O?,2)Type IIs water molecule?Na⁺-H₂O?,3)Li⁺-H₂O,their infrared absorptions of?₂ and?₃vibrations are located at 1637 cm^-1 and 3675 cm^-1,1645 cm^-1 and 3660 cm^-1,1653cm^-1 and 3650 cm^-1,respectively.The absorption at 5273 cm^-1 is attributed to the combined frequency vibration of?₂+?₃ of type IIs water molecules.The infrared absorption of HDO and D₂O is located at 2600²800 cm^-1,and the peaks at²651cm^-1 belong to the?₁ vibration of Type I and Type II D₂O,and the peaks at 2717 cm^-1and 2696 cm^-1 belong to the-OD vibration of Type I and Type II HDO,peaks at 2765cm^-1 and 2749 cm^-1 are attributed to Type I and Type II D₂O,respectively.And the peak at 2876 cm^-1 belongs to combination of the?₃ vibration and libration of Type I D₂O.There are three Raman patterns of channel water of the Dayakou emerald:high-alkali,medium-alkali and low-alkali types,and the high-alkali type is dominant.