Naslov
Analysis of tufa from Guangxi (China)

Autori
Frančišković-Bilinski, Stanislav ; Bilinski, Halka ; Barišić, Delko ; Horvatinčić, Nada ; Yuan, Daoxian

Izvornik
Acta Geologica Sinica (English Edition) (1000-9515) 77 (2003), 2; 267-275

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
tufa in Guangxi; mineral composition; elements; radionuclides; chronological data; climatic optimum

Sažetak
The paper presents analysis of characteristic karst tufa from Guangxi (China), which have not been studied before. A comparison with tufa from Dinaric Karst of Croatia is discussed in view of C-type climate. The major mineral was calcite. Minor minerals were quartz and dolomite, depending on location. The content of calcium carbonate varied from 65-92 %, and of magnesium carbonate from 0.03-1.77 %. Among other elements, the most abundant was Fe from 0.02 - 1.50 % and Ti from 0.15-0.27 %. Many other trace elements (V, Cr, Mn, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Y, Zr, Hg and Pb) were also present. Specific activity of radionuclides 40K, 232Th, 137Cs, 226Ra and 238U was different in all samples. Concentration of U in tufa was close to that reported for sedimentary carbonate. Low concentration of 137Cs indicated that this part of the world was not exposed to nuclear explosions. The concentration of 226Ra was highest in Mashan County. The ratio 238U/226Ra (0.21-0.71) in tufa from Mashan County was significantly lower than the theoretical value of 1. In 5 of 11 studied samples stable isotopes ?13C and ?18O were analyzed. They were dated by 14C method. One tufa originated from Pleistocene and others from Holocene. Because all of the tufa samples contained traces of Na and K, and K < Na, according to classification of Liu and He (1994), tufa from Guangxi belong to the CO2-outgassing "N" type.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Geologija, Kemija

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