Record details

    Low-hafnium zircon from alluvial and colluvial placers in northern Bohemia: composition and possible sources
Statement of responsibility
    Jaromír Ulrych, Pavel Uher
    Uher, Pavel
    Ulrych, Jaromír
Source title - serial
    Geologia sudetica
    Vol. 32, no. 2
    p. 139-146
    1 obr., 1 fot., 2 tab., 27 bibl.
    Zkr. název ser.: Geol. sudetica.
Subject group
    alkalický bazalt
    brekcie vulkanická
    kenozoické vulkanity Českého masivu
    kvartér Českého masivu
    nefelinický syenit
    oblast snosová
Geographical name
    Jiřetín pod Jedlovou (Děčín)
    Jizerské hory-Jizerská louka
    Košťálov (Litoměřice)
    Linhorka (Litoměřice)
    Třebenice (Litoměřice)
Abstract (in english)
   Low-hafnium zircon is, together with pyrope, sapphire and magnesian ferri-ilmenite, a widespread heavy mineral in three historical placers of precious stones in N Bohemia. The chemical compositions of zircon from all three localities (Třebenice area, Jizerská louka Meadow, Sýkoří důl Valley) are appreciably similar. Zircon forms large, 1 to 7 mm long homogenous or oscillatory zoned crystals, generally low in Hf (0.45-1.27; aver. 0.77 wt.% HfO2), Y, REE, U, Th and Ca. The genetic association of this zircon with nepheline syenite or pegmatite is doubtful as zircon from this rock found in xenoliths in a nearby alkali basalt pipe breccia from Košťálov Hill represents the Hf-rich type (1.57-1.97; aver. 1.73 wt.% HfO2). Consequently, low-hafnium zircon most probably originated from unknown coarse-grained products of early magmatic crystallisation of an alkali basalt magma forming explosive pipe breccias
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
Entered date
    13. 2. 2008
Import date
    8. 8. 2012