Inclusions in anhydrite crystals from blue halite veins in the Kłodawa Salt Dome (Zechstein, Poland)

Abstract

The oc cur rence of both the blue and vi o let halites is one of the most in ter est ing phe nom ena in na ture. De spite nu mer ous labo ra tory and field works, their or i gin in nat u ral evaporitic en vi ron ments has not been sat is fac to rily ex plained. In the K³odawa Salt Dome (Zechstein, Cen tral Po land), blue or vi o let halites oc cur rel a tively fre quently. Their ac cu mu la tions dif fer in size and in ten sity of colours. In this pa per, pet ro log i cal fea tures of anhydrite crys tals de rived from one of the larg est out crops of the blue ha lite at the K³odawa Salt Mine are pre sented. Anhydrite is one of solid in clu sions en coun tered in blue-col oured halite crys tals. Spe cial at ten tion was paid to fluid in clu sions pres ent in this anhydrite. The microthermometric mea sure ments showed two di rec tions of ho mog e nisation, i.e., to wards the liq uid phase (LG®L, LL®L) or to wards the gas phase (LG®G). In the for mer case, the tem per a tures ranged from 174 to 513°C, whereas in the lat ter one, the val ues from 224 to 385°C were mea sured. The com po si tion of in clu sions is rel a tively vari able. We can ob serve trans par ent and opaque daugh ter min er als as well as CO 2 in the liq uid phase ac com pa nied by a vari able amount of meth ane or hy dro gen sul phide. These fea tures of inclu sions in di cate that anhydrite crys tals and, thus, blue ha lite were formed un der the in flu ence of hy dro ther mal con di tions. Ob ser va tions in the mine work ings com bined with pet ro log i cal stud ies en able to con clude that blue colouration of ha lite crystals is con trolled by three fac tors: a high tem per a ture, re duc ing con di tions and de fects in ha lite lat tice re lated to tec tonic stress.Key words: blue ha lite, hy dro ther mal en vi ron ment, salt domes, anhydrite, epigenetic salt.

Microhardness analysis of halite from different salt-bearing formations

“…The third sam ple rep re sents a "blue ha lite" (Natkaniec-Nowak and Tobo³a, 2003;Tobo³a et al, 2007;Tobo³a and Natkaniec-Nowak, 2008;Wese³ucha-Birczyñska et al, 2008;Zelek et al, 2008Zelek et al, , 2014Tobo³a, 2016) while the fourth sam ple was taken from bi tu mi nous salts (Tobo³a, 2010;Wese³ucha-Birczyñska and Tobo³a, 2016). Both types of salt oc cur in the K³odawa Salt Dome (cen tral Po land) in the form of veins or nests within al most all the Zechstein de pos its (Fig.…”

Evidence of high-temperature rock salt transformations in areas of occurrence of borate minerals (Zechstein, Kłodawa salt dome, Poland)

“…Lab o ra tory stud ies on phase tran si tions in ar ti ficially formed and nat u ral bo rate min er als clearly de ter mine the tem per a tures above which those min er als crys tal lise in a reg ular sys tem (for congolite: 339°C and for boracite: 270°C - Car pen ter, 1996, 1997;Wachowiak and Tobo³a, 2014). "Blue ha lite" veins rep re sent an other type of salt rock al tered at high tem per a tures (Tobo³a, 2016). Based on micro thermometric de ter mi na tions of fluid in clu sions in anhydrite that oc cur in the coloured ha lite, tem per a tures of up to 513°C were es timated (Tobo³a, 2016).…”

“…"Blue ha lite" veins rep re sent an other type of salt rock al tered at high tem per a tures (Tobo³a, 2016). Based on micro thermometric de ter mi na tions of fluid in clu sions in anhydrite that oc cur in the coloured ha lite, tem per a tures of up to 513°C were es timated (Tobo³a, 2016). In both cases the ranges of those tem -per a tures con sid er ably ex ceed the val ues re lated to the geother mal gra di ent, i.e.…”

Long Term Analysis of Deformations in Salt Mines: Kłodawa Salt Mine Case Study, Central Poland

“…The salt layers are covered by the gypsum-anhydritic-clay cap from the dissolution of the rock salt (residuum) and its thickness is from few to max. 250 m (Werner et al, 1960;Burliga 2006Burliga , 2014Burliga & Misiek, 1997;Toboła, 2016). Upward movement of salt and the structural evolution of the dome started in Triassic and continued till Tertiary (Krzywiec, 2004).…”

“…The region is characterised by the most complete lithostratigraphic profile (Fig. 1A) and maximum thickness of Zechstein salt-bearing formation (Dadlez et al, 1995;Dadlez, 2003;Krzywiec, 2004Krzywiec, , 2006Toboła, 2016).…”