A NEW MINERAL——FLUORBRITHOLITE-(CE)

: The new mineral fluorbritho!ite-(Ce)occurs in nepheline syenite-marble xenoliths, sodalite syenite xenoliths and pegmatite dikes at Mont St. Hilaire, Quebec. It is associated mainly with analcine ,microclme , aegirine , zircon , biotite, pyro-phanite. astrophyllite ?ancylite, natrolite,monaziie etc.The mineral is hexagonal ,P63/m -with a 9. 517(5) A , c 6. 983(4) A,c/a 0. 7337,? 547. 7(8) A3,Z=2. The strongest X-ray pmvder diffraction lines and their relative intensities (visual)are:2. 851(100),2. 821(30),2. 753(30),1. 970(20),1. 969(30)(for MSH-3).Fluorbritholite-(Ce) crystal is shown prismatic. Its colour is pale yellow, tan, reddish-brown. Streak colourless to pale brown ; Lustre adamantine ; Opaque to translucent; Hardness 5 ; Brittle; Cleavage { 0001 } distinct; Fracture even to conchoidal; Density 4. 66(1) (meas} or 4. Q6g/cm3(calc. ) ; Non-fluorscent. Optically umaxial (-). w 1. 792(5),? 1. 786(5) in Na light; Nonpleochroic.Electron microprobe analyses correspond to (CeL 69 La1.02Na0.82 Nd0.44 Sr0.30 Ca0.17 Mn0.17 Y0.09 Pr0.06 Th0.03 Fe0.01) ?4.32(Si232 P0.61 ) ?2.93 O11.81 F1.19,the ideal structural formula is(PEE,Ca)5(Si,P)3012F.Britholite-(Cc) and britholite-(Y) should be renamed re-spectively ,hydroxylbritholite-(Ce) and hydroxylbrithblite(Y) to be suggested in discussion section.

Petrogenesis and Tectonic Implications of Peralkaline A-Type Granites and Syenites from the Suizhou-Zaoyang Region,Central China

In this study, we present systematic petrological, geochemical, LA-ICP-MS zircon U-Pb ages and Nd isotopic data for the A-type granites and syenites from Suizhou-Zaoyang region. The results show that the peralkaline A-type granites and syenites were episodically emplaced in Suizhou-Zaoyang region between 450±3 and 441±7 Ma which corresponds to Late Ordovician and Early Silurian periods, respectively. Petrologically, the syenite-peralkaline granite association comprises of nephefine normative-syenite and alkaline granite in Guanzishan and quartz normative syenite and alkafine granite in Huangyangshan. The syenite-granite associations are ferroan to alkali in composition. They depict characteristics of typical OIB （oceanic island basalts） derived A-type granites in multi-elements primitive normalized diagram and Ybffa vs. Y/Nb as well as Ce/Nb vs. Y/Nb binary plots. Significant depletion in Ba, Sr, P, Ti and Eu indicates fractionation of feldspars, biotite, amphiboles and Ti-rich augite. The values of eNd（t） in Guanzishan nepheline syenite and alkaline granite are ＋1.81 and ＋2.26, respectively and the calculated two-stage model age for these rocks are 1 040 and 1 003 Ma, respectively. On the other hand, the Huangyangshan alkaline granite has eNd（t） values ranging from ＋2.61 to ＋3.46 and a relatively younger two-stage Nd model age values ranging from 906 to 975 Ma, respectively. Based on these data, we inferred that the Guanzishan nepheline syenites and granites were formed from fractional crystallization of OIB-like basic magmas derived from upweliing of metasomatized lithospheric mantle. The Huangyangshan quartz syenite and granite on the other hand, were formed from similar magmas through fractional crystallization with low input from the ancient crustal rocks. Typically, the rocks exhibit Al-type granite affinity and classified as within plate granites associated with the Ordovician crustal extension and the Silurian rifting.