deep seated fluids
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2019 ◽  
Vol 98 ◽  
pp. 12012
Author(s):  
Gabriella Magro ◽  
Enrica Droghieri ◽  
Fabrizio Gherardi

In the frame of EU-funded DESCRAMBLE project, the Venelle 2 well was deepened down to 2900 m b.g.l. to test novel drilling techniques, and to improve the knowledge of physical-chemical conditions of super-hot horizons in the Larderello geothermal field, Central Italy. The major seismic reflectors present in the area were the target of the drilling, to verify their potential as geothermal reservoirs of supercritical fluids. No significant fluid entries were observed during the operations. Noble gases were analysed in the emerging drilling fluids to determine whether deep-seated fluids with a different signature than those currently discharged by productive wells entered the borehole. Despite the predominant atmospheric signature of the noble gas suite, 3He/4He values up to 1.59 Ra were measured, and the contribution of a deep component with ~4 Ra was hypothesised by extrapolation of binary mixing trends.


Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-22 ◽  
Author(s):  
Yan Zhang ◽  
Runsheng Han ◽  
Pingtang Wei ◽  
Lei Wang

This work investigates the ultra-large Huize Pb–Zn deposit, based on the results of preceding studies and detailed field geological surveys. The existing findings were reorganized and reinterpreted and supplemented with C–H–O isotopic measurements, which resulted in the identification of two different metallogenic fluids: a high temperature, low salinity, and acidic Fluid A, which originates from deep-seated fluids and is enriched in lighter C and O isotopes (−3‰ < δ13C‰ < −4‰; 10‰ < δ18O‰ < 17‰; −92‰ < δD‰ < −50‰), and a low temperature, high salinity Fluid B, which is a subsurface brine formed by atmospheric precipitation. Fluid B is characterized by heavier C–O–H isotopic compositions (−2‰ < δ13C‰ < 1‰; 2‰ < δ18O‰ < 24‰; −66‰ < δD‰ < −43‰) than Fluid A and cycles continuously within the strata. We hypothesize that the Huize Pb–Zn deposit is the result of large-scale fluid migration from deep regions of the crust. These upward-moving fluids extracted metallic elements from carbonate strata of various ages, forming a metal-rich metallogenic fluid (Fluid A). After higher-grade ores were precipitated from the fluid following decompression boiling, it then mixed with Fluid B and continued to precipitate sulfides.


2013 ◽  
Vol 32 (2) ◽  
pp. 195-202 ◽  
Author(s):  
Baode Wang ◽  
Shuyin Niu ◽  
Aiqun Sun ◽  
Jianzhen Zhang ◽  
Xiang Wang ◽  
...  

2012 ◽  
Vol 55 (4) ◽  
Author(s):  
Francesco Italiano ◽  
Marcello Liotta ◽  
Mauro Martelli ◽  
Giovanni Martinelli ◽  
Riccardo Petrini ◽  
...  

<p>A periodic sampling of the groundwaters and dissolved and free gases in selected deep wells located in the area affected by the May-June 2012 southern Po Valley seismic sequence has provided insight into seismogenic-induced changes of the local aquifer systems. The results obtained show progressive changes in the fluid geochemistry, allowing it to be established that deep-seated fluids were mobilized during the seismic sequence and reached surface layers along faults and fractures, which generated significant geochemical anomalies. The May-June 2012 seismic swarm (mainshock on May 29, 2012, M 5.8; 7 shocks M &gt;5, about 200 events 3 &gt; M &gt; 5) induced several modifications in the circulating fluids. This study reports the preliminary results obtained for the geochemical features of the waters and gases collected over the epicentral area from boreholes drilled at different depths, thus intercepting water and gases with different origins and circulation. The aim of the investigations was to improve our knowledge of the fluids circulating over the seismic area (e.g. origin, provenance, interactions, mixing of different components, temporal changes). This was achieved by collecting samples from both shallow and deep-drilled boreholes, and then, after the selection of the relevant sites, we looked for temporal changes with mid-to-long-term monitoring activity following a constant sampling rate. This allowed us to gain better insight into the relationships between the fluid circulation and the faulting activity. The sampling sites are listed in Table 1, along with the analytical results of the gas phase. […]</p>


2010 ◽  
Vol 297 (3-4) ◽  
pp. 567-576 ◽  
Author(s):  
Yoshiro Nishio ◽  
Kei Okamura ◽  
Masaharu Tanimizu ◽  
Tsuyoshi Ishikawa ◽  
Yuji Sano

2000 ◽  
Vol 27 (14) ◽  
pp. 2029-2032 ◽  
Author(s):  
David A. Wark ◽  
E. Bruce Watson

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