Epithermal Fluorite Deposits in Transbaikalia (Geochemical Features, Sources of Matter and Fluids, and Genesis)

2021 ◽  
Vol 62 (4) ◽  
pp. 415-426
Author(s):  
E.I. Lastochkin ◽  
G.S. Ripp ◽  
D.S. Tsydenova ◽  
V.F. Posokhov ◽  
A.E. Murzintseva
Keyword(s):  
Meteoric Water ◽  
Isotope Composition ◽  
Spatial Proximity ◽  
Thermal Waters ◽  
Sr Isotope ◽  
Light Isotope ◽  
Geochemical Parameters ◽  
Nd Systems ◽  
Deep Source ◽  
The Impact

Abstract —We consider the isotope-geochemical features of epithermal fluorite deposits in Transbaikalia, including the REE compositions, Sr isotope ratios, Sm–Nd systems, and isotope compositions of oxygen, carbon, hydrogen, and sulfur. The 87Sr/86Sr ratios in fluorites are within 0.706–0.708, and the εNd values are negative. Oxygen in quartz, the main mineral of the deposits, has a light isotope composition (δ18O = –3.4 to +2.6‰), and the calculated isotope composition of oxygen in the fluid in equilibrium with quartz (δ18O = –9 to –16‰) indicates the presence of meteoric water. The latter is confirmed by analysis of the isotope compositions of oxygen and hydrogen in gas–liquid inclusions in fluorites from three deposits. These isotope compositions are due to recycling caused by the impact of shallow basic plutons. The isotope composition of sulfur indicates its deep source. During ascent, sulfur became enriched in its light isotope (δ34S = –1.8 to –7.7‰). We assess the association of fluorite ores with basaltoids widespread in the study area. The isotope and geochemical parameters suggest their spatial proximity. Probably, the basaltoids were responsible for the recycling of meteoric water. It is shown that the epithermal fluorite deposits formed by the same mechanism as fissure–vein thermal waters in western Transbaikalia.

New data on microelement and isotope composition of thermal springs in Tajikistan

2018 ◽  
pp. 109-116
Author(s):  
T. A. Kireeva ◽  
F. S. Salikhov ◽  
A. Y. Bychkov ◽  
N. A. Kharitonova ◽  
A. V. Romashkina
Keyword(s):  
Isotope Fractionation ◽  
Meteoric Water ◽  
Isotope Composition ◽  
Tien Shan ◽  
Thermal Springs ◽  
Thermal Waters ◽  
Water Line ◽  
Icp Ms ◽  
Mountain Systems ◽  
Subsurface Temperatures

This article provides detailed information about the geological setting and the chemical composition of some thermal springs (Garm-Chashma, Firuza-MGU, Tandykul, Obigarm, Khojaоbigarm) located within the Pamirs and the Tien Shan mountain systems. This is the first report describing the micro components data for investigated springs obtained by the ICP-MS method. The calculated ratios of B:Cl, B:Br and Li:Rb:Cs allow to define the genesis of the studied thermal springs. New data on the contents of 18O and D indicate that the studied thermal waters are most likely meteoric, while a slight drift from the meteoric water line is the result of isotope fractionation in water-rock-gas processes. The estimated subsurface temperatures for these thermal waters vary from 136 °C to 240 °C based on the K:Na geothermometer.

Nd, Pb, and Sr isotope composition of juvenile magmatism in the Mesozoic large magmatic province of northern Chile (18–27°S): indications for a uniform subarc mantle

2006 ◽  
Vol 152 (5) ◽  
pp. 571-589 ◽  
Author(s):  
Friedrich Lucassen ◽  
Wolfgang Kramer ◽  
Viola Bartsch ◽  
Hans-Gerhard Wilke ◽  
Gerhard Franz ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Northern Chile ◽  
Sr Isotope

The impact of temperature on the degree of structurization of water of different isotope composition

2017 ◽  
Vol 39 (4) ◽  
pp. 185-190
Author(s):  
V. V. Goncharuk ◽  
I. Yu. Romanyukina ◽  
M. D. Skil’skaya ◽  
A. I. Marynin ◽  
A. V. Syroeshkin ◽  
...  
Keyword(s):  
Isotope Composition ◽  
The Impact

scholarly journals Comment on “Origin of water in the Badain Jaran Desert, China: new insight from isotopes” by Wu et al. (2017)

2018 ◽  
Vol 22 (8) ◽  
pp. 4449-4454 ◽  
Author(s):  
Lucheng Zhan ◽  
Jiansheng Chen ◽  
Ling Li ◽  
David A. Barry
Keyword(s):  
Lake Water ◽  
Meteoric Water ◽  
Isotope Composition ◽  
Qilian Mountains ◽  
Precipitation Rate ◽  
Badain Jaran Desert ◽  
Isotopic Evidence ◽  
Isotope Data ◽  
Local Areas ◽  
The Qilian Mountains

Abstract. Precipitation isotope data were used to determine the origin of groundwater in the Badain Jaran Desert (BJD) in the study of Wu et al. (2017). Both precipitation and its isotope composition vary seasonally, so arithmetic averages of precipitation isotope values poorly represent the isotope composition of meteoric water. Their finding that the BJD groundwater is recharged by modern meteoric water from local areas including the southeastern adjacent mountains was based on arithmetic averaging. However, this conclusion is not supported by the corrected mean precipitation isotope values, which are weighted by the precipitation rate. Indeed, the available isotopic evidence shows that modern precipitation on the Qilian Mountains is more likely to be the main source of the groundwater and lake water in the BJD, as found by Chen et al. (2004).

Out of sight, out of mind? Supplier spatial proximity in French public procurement

2014 ◽  
Vol 27 (6) ◽  
pp. 486-500 ◽  
Author(s):  
Olivier Mamavi ◽  
Haithem Nagati ◽  
Frederick T. Wehrle ◽  
Gilles Pache
Keyword(s):  
Public Procurement ◽  
Spatial Proximity ◽  
Management Competencies ◽  
Content Type ◽  
The Public ◽  
Feature Evaluation ◽  
Negative Effect ◽  
New Type ◽  
The Difference ◽  
The Impact

Purpose – The purpose of this paper is to study the impact of spatial proximity on supplier selection in the French public sector. While French public procurement legislation forbids consideration of supplier location in the procurement process, public contractors may still rely on spatial proximity for complex transactions necessitating mutual adjustments with suppliers. Design/methodology/approach – Using French Official Journals (BOAMP), the authors compiled 565,557 transactions completed on three public procurement markets between 6,182 contractors and 26,570 suppliers, over a period of six years (between 2006 and 2011). The authors conducted a two-level hierarchical linear auto-regression analysis and a feature evaluation analysis for all transactions. Findings – The paper finds significant variation between the transactions on different markets: a negative effect of spatial proximity on the number of contract notices in the public market and a positive effect of spatial proximity on the number of notices in the services and supplies markets. The difference lies in the levels of mutual adjustment required to optimally manage the relationship between public contractor and supplier. Research limitations/implications – The research is based on an econometric analysis conducted uniquely in the French context, which calls into question the external validity of the results obtained. The study also rests on segmentation into three aggregate markets, which might be considered too general. Originality/value – Rather than analyze public contractors’ perceptions of the importance of the criterion of spatial proximity, the paper examines 565,557 actual transactions. The results point to the emergence of a new type of relationship with certain suppliers, which should lead public contractors to integrate relationship management competencies, in addition to legal and economic competencies, in the organization of calls for tenders.

scholarly journals Absence of Saharan dust influence on the strontium isotope ratios on modern trees from the Bahamas and Turks and Caicos Islands

2018 ◽  
Vol 89 (2) ◽  
pp. 394-412 ◽  
Author(s):  
Rick Schulting ◽  
Mike Richards ◽  
John Pouncett ◽  
Bryan Naqqi Manco ◽  
Ethan Freid ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Saharan Dust ◽  
Soil Types ◽  
Sr Isotope ◽  
The Bahamas ◽  
Turks And Caicos Islands ◽  
Order Of Magnitude ◽  
The Caribbean ◽  
The Impact ◽  
Bahamian Archipelago

AbstractWe report on strontium (87Sr/86Sr) isotope results from 91 modern trees growing on the Bahamas and Turks and Caicos Islands. The average87Sr/86Sr ratio of 0.709169±0.000010 is consistent with the late Quaternary limestone of the islands and with the modern ocean value. The absence of any detectable influence of87Sr-enriched Saharan dust is notable, given the known contribution of this material to both past and recent soils of the Caribbean. Our results indicate that the impact of Saharan dust to the modern biosphere of the Bahamian archipelago is at least an order of magnitude less than modeled in currently available strontium isoscapes for the circum-Caribbean. We suggest that the bioavailability of Sr in Saharan dust may be considerably less than previously thought. Nevertheless, further work could usefully be carried out in the Bahamian archipelago on plants with different rooting depths, growing on different soil types and on limestone of different ages. Our results have particular relevance for the refinement of existing strontium isoscapes and the archaeological provenience of artifacts, animals, and people in the circum-Caribbean.

Sign in / Sign up

Export Citation Format

Share Document