کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8910399 | 1637495 | 2018 | 52 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Origin of methane and light hydrocarbons in natural fluid emissions: A key study from Greece
ترجمه فارسی عنوان
منشاء متان و هیدروکربن های سبک در انتشار سیال طبیعی: یک مطالعه کلیدی از یونان
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
چکیده انگلیسی
Greece, a country characterised by intense seismic and volcanic activity, has a complex geodynamic and geological setting that favours the occurrence of many gas manifestations. In this study, we address the origin of CH4 and light hydrocarbons in cold and thermal emissions discharging along the Hellenic territory. Also, we investigate their possible relationship with the main geochemical composition of the gases and the different geological settings of the sampling sites. For this purpose we collected 101 new samples that were analysed for their chemical (O2, N2, CH4, CO2, He, Ne, Ar, H2, H2S and C2-C6 hydrocarbons) and isotopic (R/RA, δ13C-CO2, δ13C-CH4 and δ2H-CH4) composition. Results show that CH4 presents a wide range of concentrations (from <0.5 to 925,200â¯Î¼mol/mol) and isotopic values (δ13C-CH4 from â79.8 to +45.0â° vs. V-PDB; δ2H-CH4 from â311 to +301â° vs. V-SMOW). Greece was subdivided in four geologic units (External [EH] and Internal [IH] Hellenides, Hellenic Hinterland [HH] and active Volcanic Arc [VA]) and a decreasing CH4 concentration from EH to HH was recognized, whereas CH4 showed intermediate concentrations in VA. The CH4/(C2H6â¯+â¯C3H8) ratios (from 1.5 to 93,200), coupled with CH4 isotopic features, suggest that the light alkanes derive from different primary sources and are affected by secondary processes. An almost exclusive biotic, mainly microbial, origin of CH4 can be attributed to EH gases. Cold gases at IH have mainly a thermogenic origin, although some gases connected to continental serpentinization may have an abiogenic origin. Methane in gases bubbling in thermal waters of IH, HH and VA and fumarolic gases of the VA seem to have an abiogenic origin, although their chemical and isotopic characteristics may have been produced by secondary oxidation of thermogenic CH4, a process that in some of the sampled gases causes extremely positive isotopic values (δ13C-CH4 up to +45.0â° vs. V-PDB and δ2H-CH4 up to +301â° vs. V-SMOW).
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemical Geology - Volume 479, 20 February 2018, Pages 286-301
Journal: Chemical Geology - Volume 479, 20 February 2018, Pages 286-301
نویسندگان
Kyriaki Daskalopoulou, Sergio Calabrese, Fausto Grassa, Konstantinos Kyriakopoulos, Francesco Parello, Franco Tassi, Walter D'Alessandro,