Fluid compositions reveal fluid nature, metal deposition mechanisms, and mineralization potential: An example at the Haobugao Zn-Pb skarn, China

Geology ◽  
2020 ◽  
Author(s):  
Qihai Shu ◽  
Zhaoshan Chang ◽  
John Mavrogenes
Keyword(s):  
Inductively Coupled Plasma ◽  
Isotope Composition ◽  
Northeastern China ◽  
Metal Deposition ◽  
Mass Balance Calculation ◽  
Inductively Coupled ◽  
Mineralization Potential ◽  
Plasma Mass Spectrometry ◽  
Absolute Concentrations ◽  
Potential Tool

Fluid inclusion compositions obtained from laser ablation–inductively coupled plasma–mass spectrometry at the Haobugao Zn-Pb skarn in northeastern China provide constraints on fluid origin, evolution, and metal deposition mechanisms and an example of evaluating mineralization potential. Metal concentrations in the prograde fluids were high (up to 1.4 wt% Zn and 1.8 wt% Pb) but remained in solution, likely due to the high temperatures (440–575 °C) and salinities (35.4–45.3 wt% NaCl equivalent). Absolute concentrations of elements (e.g., Rb and Na) and mass ratios (e.g., Zn/Na and K/Na) reveal that the early, prograde fluids were magmatic, consistent with the oxygen isotope composition of fluids (δ18OH2O = 5.5‰–8.5‰). Later mixing with a meteoric fluid caused dilution and Zn-Pb deposition, as revealed by lowered element concentrations and Pb/(Na + K) and Zn/(Na + K) ratios in the sulfide-stage fluid inclusions. Elevated Ca/K ratios in sphalerite-hosted inclusions indicate fluid-carbonate reactions that buffered fluid pH, also facilitating Zn-Pb precipitation. Although cassiterite and molybdenite occur locally at Haobugao, mass balance calculation shows low metal endowment (maximum 2900 t Sn and 2200 t Mo) of the system. Furthermore, the generally unchanged Sn/(Na + K) and Mo/(Na + K) ratios from pre- to late-mineralization fluids suggest that the fluids were never saturated in Sn and Mo. Therefore, finding much Sn or Mo at Haobugao is unlikely. This demonstrates a potential tool for evaluating the metal endowment of a mineral prospect, which may guide exploration.

Single nanoparticle analysis by ICPMS: a potential tool for bioassay

2018 ◽  
Vol 33 (1) ◽  
pp. 57-67 ◽  
Author(s):  
Jianyu Hu ◽  
Dongyan Deng ◽  
Rui Liu ◽  
Yi Lv
Keyword(s):  
Inductively Coupled Plasma ◽  
High Sensitivity ◽  
Absolute Quantification ◽  
Metallic Nanoparticle ◽  
Promising Technique ◽  
Inductively Coupled ◽  
Single Nanoparticle ◽  
Plasma Mass Spectrometry ◽  
Dynamic Linear Range ◽  
Potential Tool

Inductively coupled plasma mass spectrometry (ICPMS) has already been demonstrated as a promising technique for metallic nanoparticle tagged bioassays due to its high sensitivity, wide dynamic linear range, and more importantly multiplex and absolute quantification ability.

Precise isotope analysis of tellurium by inductively coupled plasma mass spectrometry using a double spike method

2018 ◽  
Vol 33 (7) ◽  
pp. 1233-1242 ◽  
Author(s):  
Yusuke Fukami ◽  
Jun-Ichi Kimura ◽  
Katsuhiko Suzuki
Keyword(s):  
Mass Spectrometry ◽  
Stable Isotope ◽  
Inductively Coupled Plasma ◽  
Isotope Composition ◽  
Isotope Analysis ◽  
Stable Isotope Composition ◽  
Inductively Coupled ◽  
Analytical Protocol ◽  
Plasma Mass Spectrometry ◽  
Sample Aliquot

We present an analytical protocol to determine the Te/Se ratio and stable isotope composition of Te from a single sample aliquot.

Geochemistry and Crystallization Conditions of Magmas Related to Porphyry Mo Mineralization in Northeastern China

2020 ◽  
Vol 115 (1) ◽  
pp. 79-100 ◽  
Author(s):  
Hegen Ouyang ◽  
Jingwen Mao ◽  
Ruizhong Hu
Keyword(s):  
Inductively Coupled Plasma ◽  
Melt Inclusions ◽  
Northeastern China ◽  
Silicate Melts ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry ◽  
Crystallization Conditions ◽  
Porphyry Mo Deposit ◽  
The One ◽  
Porphyry Mo Deposits

Abstract To better understand processes leading to porphyry Mo deposit formation, the metal content, volatile content, and crystallization conditions of melt inclusions from pre- and synmineralization intrusions in six porphyry(-skarn) Mo deposits of northeastern China (Aolunhua, Hashitu, Lanjiagou, Songbei, Wanbaoyuan, and Yangjiazhangzi) were investigated by means of laser ablation-inductively coupled plasma-mass spectrometry and electron microprobe analysis. The ore-forming silicate melts were one to four times more evolved than average granite with 1 to 7 ppm Mo. The ore-related intrusions crystallized predominantly at 760° to 690°C and 3.7 to 1.0 kbar, except for the one at Hashitu, which crystallized at 770° to 740°C and lower pressures (2.0–1.0 kbar). Fertile silicate melts at Hashitu contain up to 0.4 wt % F, 0.03 to 0.09 wt % Cl, 5.0 to 7.0 wt % H2O, 10 to 24 ppm Cs, and 200 to 500 ppm Rb, whereas those at Yangjiazhangzi and Wanbaoyuan contain less Cs (3–6 ppm and 5–7 ppm, respectively), less Rb (180–220 ppm and 200–240 ppm, respectively), and negligible F (<0.15 wt %) but have similar Cl (0.03–0.05 wt %) and H2O (5.3–6.5 wt % and 4.0–5.2 wt %, respectively) contents. Calculated melt viscosities in fertile magmas (log η = 4.3–6.1 Pa s) are at the lower end of the values reported for felsic melts at the same temperature. Comparison between syn- and premineralization intrusions in individual deposits reveals that the ore-related intrusions were similarly evolved and had similar Mo contents and crystallization conditions as the nonmineralizing intrusions. The only difference is that the premineralization intrusions tend to occur as batholiths. The key to porphyry Mo mineralization lies in the focusing of fluid into and through a small rock volume on the top of the intrusion. For the studied porphyry Mo deposits, the mineralizing magmas are all Mo poor, indicating Mo enrichment is not required to form porphyry Mo deposits. Metal endowments in porphyry Mo deposits have no direct relationship with the composition and crystallization condition of mineralizing melts but are linked with the fluid flux released from the underlying magma chamber through a cupola.

Magmatic Origin for Sediment-Hosted Au Deposits, Guizhou Province, China: In Situ Chemistry and Sulfur Isotope Composition of Pyrites, Shuiyindong and Jinfeng Deposits

2018 ◽  
Vol 113 (7) ◽  
pp. 1627-1652 ◽  
Author(s):  
Zhuojun Xie ◽  
Yong Xia ◽  
Jean S. Cline ◽  
Michael J. Pribil ◽  
Alan Koenig ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Inductively Coupled Plasma ◽  
Isotope Composition ◽  
Sulfide Minerals ◽  
Guizhou Province ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
S Isotope

Abstract The southwest Guizhou Province, China, contains numerous sediment-hosted Au deposits with Au reserves greater than 700 tonnes. To date, the source of ore fluids that formed the Guizhou sediment-hosted Au deposits is controversial, hampering the formulation of genetic models. In this study, we selected the Shuiyindong and Jinfeng Au deposits, the largest strata-bound and fault-controlled deposits in Guizhou, respectively, for detailed research on pyrite chemistry and S isotope composition using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and laser ablation-multicollector-inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS), respectively. Petrography and pyrite chemistry studies distinguished five generations of pyrite. Among these, pre-ore pyrite 2 and ore pyrite are the most abundant types in the deposits. Pre-ore pyrite 2 is anhedral to euhedral and with ~2,639 ppm As and wider ranges of Cu, Sb, and Pb (<~22–4,837 ppm, <~6 to 532 ppm, and <~4 to 1,344 ppm, respectively). Gold in pre-ore pyrite 2 is below the detection limit of LA-ICP-MS (~2 ppm). Pre-ore pyrite 2 is interpreted to have a sedimentary (syngenetic or diagenetic) origin. Ore pyrite commonly rims the four identified pre-ore pyrites or occurs as individual, anhedral to euhedral crystals. Ore pyrite is enriched in Au (~641 ppm), As (~9,147 ppm), Cu (~1,043 ppm), Sb (~188 ppm), Hg (~43 ppm), and Tl (~22 ppm) in both deposits. Ore pyrite formed mainly by sulfidation of Fe in Fe-bearing host rocks, mainly Fe dolomite, and As, Cu, Sb, Hg, and Tl, also in ore fluids, were incorporated into ore pyrite. In situ δ34S isotope ratios for pre-ore pyrite 2 and ore pyrite were measured by LA-MC-ICP-MS. Pre-ore pyrite 2 from Shuiyindong and Jinfeng deposits resulted in δ34S values ranging from −0.8 to +3.4‰ and from 5.1 to 10.5‰, respectively. Analyses of ore pyrite from the Shuiyindong have δ34S values that vary from −3.3 to +2.5‰, with a median of 0.7‰; analyses of ore pyrite from the Jinfeng range from 8.9 to 11.2‰, with a median at 10.3‰. Available bulk and in situ δ34S data in the literature for pre-ore pyrites 1 and 2 and ore-related sulfide minerals including ore pyrite, arsenopyrite, and late ore-stage stibnite, realgar, orpiment, and cinnabar from several Guizhou sediment-hosted Au deposits were compiled for comparison. Pre-ore-stage pyrites from Guizhou sediment-hosted Au deposits have a broad range of δ34S values, from −33.8 to + 17.9‰ (including in situ and available bulk δ34S data). Ore-related sulfide minerals in all Guizhou sediment-hosted Au deposits, except Jinfeng, have very similar δ34S values, and most data plot between ~−5 and +5‰. In the Jinfeng deposit, the ore-related sulfide minerals exhibit δ34S values ranging from 1.9 to 18.1‰, with most data plotting between 6 and 12‰. The broad range of S isotope compositions for the sedimentary pyrites (pre-ore pyrites 1 and 2) indicate that S in these pre-ore pyrites was most likely generated by bacterial reduction from marine sulfate. The narrow range of δ34S values (~−5–+5‰) for ore-related sulfide minerals in all Guizhou sediment-hosted Au deposits, excepting the Jinfeng deposit, suggests that the deposits may have formed in response to a single widespread metallogenic event. As the S isotope fractionation between hydrothermal fluids and sulfide minerals in a sulfide-dominated system is small (<2‰) at ~250°C, the initial ore fluids that formed the Guizhou sediment-hosted Au deposits would have had δ34S values similar to the ore-related sulfide minerals, between ~−5 and +5‰. At Jinfeng, initial ore fluids may have mixed with local fluids with heavier δ34S, possibly basin brine (δ34Sbasin brine >18‰), resulting in elevated δ34S values of ore-related sulfide minerals and especially late ore-stage sulfide minerals. Although few igneous rocks are exposed in the mining area around these deposits, there is evidence of magmatic activity ~20 km away. Furthermore, gravity and magnetic geophysical investigations indicate the presence of a pluton ~5 km below the surface of the Shuiyindong district. Based on in situ S isotope results and recent data indicating proximal intrusions, we interpret a deep magmatic S source for the ore fluids that formed the Guizhou sediment-hosted Au deposits. However, as the age for Au mineralization of Guizhou sediment-hosted Au deposits is still debated, the mineralization-magma connection remains hypothetical. Identifying an ore fluid source and time frame for Guizhou Au mineralization continues to be a critically important research goal for this district.

Sign in / Sign up

Export Citation Format

Share Document