Geochemical patterns of the Akdagmadeni (Yozgat, Central Turkey) fluorite deposits and implications

Abstract

Fluorite and fluorite-bearing Pb-Zn-Ag (Cu) deposits are quite common in granitoids and associated skarn formations that are products of Late Cretaceous -Early Paleocene magmatic intrusions into Paleozoic metamorphic rocks of the so called Central Anatolian massif. This study investigates the geochemical features, mainly REE distributions, of fluorites from the Akdagmadeni fluorite and fluorite bearing PbZn -Ag (Cu) deposits. These include the vein type Tad Dere, epidote-skarn hosted Büyükçal Tepe and the skarn and granite hosted Akçakisla deposits. The REE contents of these deposits are 20.6 -48.5 ðx ¼ 36:0Þ, 61.3 -149.3 ðx ¼ 113:0Þ and 279.2-4222.4 ðx ¼ 1280:0Þ ppm for the Tad D., Büyükçal T. and Akçakisla, respectively.In general, the REE contents are intermediate to high and decrease in abundance with increasing distance from the granitic bodies. The LREE contents are dominantly higher than HREE contents and REE normalized patterns indicate decreasing abundances with increasing atomic number. These indicate that all the fluorites are early stage mineralizations. However, Tb/Ca -Tb/La ratios show distinct differences in the nature of the mineralizing fluids. The high ratios of Akçakisla fluorites are evidence of mineralizing fluids rich in late-stage differentiates from a felsic magma, while intermediate to high ratios of the Büyükçal T. fluorites are products of late-stage differentiates from hydrothermal fluids. Tad D. fluorites were mineralized under hydrothermal conditions. Decreasing SREE contents in the order of Akçakisla, Büyükçal T., and Tad D., and Sc/Eu vs Sr distribution (Sr increases with increasing distance from the magmatic rocks) also supports this order of formation. Each of the three types of fluorite deposits plot in well-defined areas in the Sc/Eu vs Sr diagram. Eu and Ce anomalies give a mixed pattern; the Tad D. fluorites have strong negative Eu anomalies indicating low T and low f o 2 mineralizing fluids. Strong positive Eu anomalies for the Akçakisla fluorites are probably due to high f o 2 : The Ce anomalies are strongly negative for the Akçakisla, negative for the Büyükçal T. and weakly negative for the Tad D. fluorites. These indicate high f o 2 conditions for the Akçakisla, intermediate for the Büyükçal T. and low for the Tad D. fluorites. Because of distinguishable differences in REE patterns, the fluorite deposits plot in well-defined areas in Sc/Eu vs Sr, (La/Yb) n -(Eu/Eu p ) n , Sr -(Eu/Eu p ) n , Sc-SREE, (Tb/Yb) n -(La/Yb) n , Tb/Ca -Tb/La diagrams, and indicate different origins and depositional histories.The homogenization temperatures ðT H Þ range from 156 to 185 8C with the corresponding salinities between 12 and 23 wt% NaCl for the Tad Dere ores, 390 to 430 8C with the corresponding salinities 8 and 12 wt% NaCl for the Akçakisla and Büyükçal Tere ores.Consequently, the field, fluid inclusion data and REE geochemistry indicate that the composition of mineralizing fluids, the locations of ore formations relative to the plutons, the mineralizing mechanisms and the prevailing...

Variation of mineralizing fluids and fractionation of REE during the emplacement of the vein-type fluorite deposit at Bozijan, Markazi Province, Iran

“…11), two samples of studied fluorites overlap with the barren fluorite deposits (i.e., lacking precious metals mineralization), and some samples do not overlap with any deposit type. Some fluorite samples fall in the field occupied by granitoid, skarn, and metamorphic-hosted Akdagmadeni fluorites in Turkey (Sasmaz et al, 2005b). That the studied fluorite veins lack potential for exploring Ag-Au mineralization is suggested in Fig.…”

“…11, again confirming that the geochemistry of REE is a creditable approach in the exploration of precious metals mineralization in fluorite deposits. Although the positive Eu anomaly is considered an indicator for precious metals mineralization in fluorite deposits (Constantopoulos, 1988;Sasmaz et al, 2005b), the fact that Bozijan fluorites are devoid of precious metals suggests that this interpretation cannot be true in all cases.…”

“…All samples are normalized to chondrite (Boynton, 1984). Data range for fluorite-bearing hydrothermal deposits in New Mexico (Eppinger and Closs, 1990), and Akdagmadeni fluorites in Turkey (Sasmaz et al, 2005b) are shown.…”

“…Moreover, many researchers (Constantopoulos, 1988;Hein et al, 1990;ƠConnor et al, 1993;Palmer and Williams-Jones, 1996;Sasmaz and Yavuz, 2007;Strong et al, 1984;Williams-Jones et al, 2000) combined geochemical data with fluid inclusion studies to unravel fluorite genesis. On the other hand, some workers applied the geochemistry of REE as an exploration tool to differentiate between precious-metal-bearing fluorite deposits and barren deposits (Constantopoulos, 1988;Eppinger and Closs, 1990;Hill et al, 2000;Sasmaz et al, 2005b). The aim of the current study is to present the geological setting, petrographic and fluid inclusion findings, and geochemistry of REEs to constrain a genetic model for the Bozijan fluorite deposit.…”

Geochemistry and Nd, Sr isotopes of the Pohrenk fluorites (Kırsehir-Turkey)

“…The presence of high value cations of the fluorites (HFS) and rare earth element values being low compared to the wall rocks show that these elements were affected by mineralising fluids (Yaman, 1985). In the (Tb/Yb) n -(La/Yb) n diagram by (Hill et al, 2000) the Pohrenk fluorite samples that were studied plot in the Akdagmadeni fluorites (Sasmaz et al, 2005) Buyukkizilcik fluorites (Uras and Calıskan, 2014) and Lordsburg Steeple Rock area (Fig. 14a).…”