Abstract:Fuchuan ophiolites in Southern Anhui Province are distribut- ed along the Qimen-Shexian一Sanyangkeng fault belt stretching in nearly E一W direction.They extend discontinuously for about 90 Km and structurally emplaced into the Proterozoic phyllite (Shangxi group).The sequence of the ophiolites is consisted, from bottom to upper, of:(1)metamorphic peridotite(serpenti- nzation harzburgite),(2)cumulus gabbro,(3)spi lite,(4)ke- ratophyre, which is covered with phyllite of Shangxi group. According to the geological and geochemical characteristics the au比or suggest;that the Fuchuan ophiolites may be formed in island arc environment, as:(1)The geological environment in formation of the Fuchuan ophiolites is Midproterozoic ancient island arc;(2)Some macroelement contents in the ophiolitic vo- lcanics are similar to those in the island arc volcanics and show more defferent from the deep一sea tholeiite(Table 2).On the diagram for classification of basalts, most of the Fuchuan ophiolite volcanics are plotted to the high-alumina basalt field, which are similar to that of New Britain volcanic arc. On the Na2O/K2O一(Na20+K20)orrelation diagram, most of the Fuchuan ophiolite volcanics are confined to the island arc volcanic field; (3)The trace element contents of volcanics in this area are also similar to that of island arc volcanics, and on the Ti一Zr and Ti一Cr discrimination diagrams(Fig. 2)they are all plotted to the is- landarc volcanics field;(4)The REE distribution pattern of the Fuchuan ophiolitie volcanics is in the same range with the island arc volcanics(Fig.3). Having study of REE and trace elements in the rocks we con- sider that the Fuchuan ophiolites may be partial melting pro- duct of upper mantle.(1)The plus-correlation between La/sm and La in gabbro, spilite and keratophyre(Fig.4)indicated that they are products of partial melting from upper mantle.The mutual supplement correlation in REE and transition metal elements be- tween metamorphic peridotite and spilite indicate that the form- er is residual solid phase and the latter is melting liquidus.(2) The gabbro and tiie spilite are obviously enriched in incornpati- ble element Ti and V, but extremely depleted in compatible ele- ment Cr and Ni, while the metamorphic peridotite is quite the contrary, which also indicate that the gabbro and the spilite are products of liquidus and the metamorphic peridotite is product of residual solid phase from upper mantle.(3)According to the model calculated from REE contents the Fuchuan ophiolites may be 5% melting product from the upper mantle(Table 6).As the residual solid phase(metamorphic peridotite)is rich in LREE,it may be considered that the Fuchuan upper mantle is the one enriched REE

Abstract:This is the first time when garnet was discovered in calcalkaline volcanic rocks of Mesozoic era in western Qinling, the composition of which is almost in coincidence with that in data reported from abroad, that is, the garnet is an almandine characterized by abundant Fe, less Mg and rare Mn, but of higherproportion of Ca. Almost all of the garnet in the rocks are the corroded ones and surrounded by euhedral-subhedral plagioclases(some are with zonary structure), which makes us believe that theseplagio clases are not the reaction rims between garnet and magma, but the products of magmatic crystallization. The crystallizing mechanism is that while the uprising magma was corroding early crystallized garnet, Ca and At contents increased around it so that it helped to form the plagioclases around the residual garnet. In the volcanic rocks there are no xenolithes of metamorphic, plutonic rocks and other minerals with the same crystallizing conditions as garnet; and in the garnet crystal there are some silicate glass inclusions, etc; and considering the data which have been published and the geologic background of the Mesozoic volcanic rocks, we think that the garnet is not the xenolith crystal of the magma, but the eary-crystallized mineral of the same magma as the mother rock. And based on that we infer that the magma which formed the rock originated from the bottom of the lower crust at a depth of more than 50 km.

Abstract:The Guanzishan intrusion located in the boundary between Suizhou city and Zaoyang county, Hubei Province, consists of jadeite-cancrinite syenite, jadeite syenite and biotite hornblende syenite from centre of the intrusion to margin. This paper stresses the study on the petrology, mineralogy,petrochemistry, REE geochemistry, age and petrogenesis of the jadeite-cancrinite syenite. Its age determined by Rb-Sr isochron is 306 Ma, suggesting that it was formed at Hercynian. On the basis of the occurrence, FeO/MgO, (87)Sr/(86)Sr(i), REE distribution pattern and P. T. conditions of jadeite-forming it is provable enough that the jadeite-cancrinite syenite is genetically related to the upper mantle materials.

Abstract:Tiantangzhai gneissis granite massif which is considered a Pre-Cambrian migmatitic granite by most references, in the authors' opinion, is product of crystallization of magma and belongs to I'u-type granite. Its emplacement age was Early Cretaceous.The concordant ages of 124.7 Ma for the zircons have been obtained. Since the emplacing of the granite, theuplifted speed of Dabieshan region is not very quick. An average, there is 0.1mm per year.

Abstract:Geochronology of Cenozoic basalts from Inner Mongolia have been systematically studied by means of K一Ar dating,where there were 14 samples from Chifeng district, 15 from Jining and 21 from Abaga. MM1200B static vacuum mass spectrometer was used for K一AI dating,The measuring errors 0f both 40Ar and 36Ar Were all 0.1-0.05% and 36Ar 1-5%and age error 5－10％（1σ). The results show the evolution of Cenozoic basalts in the area. At first,the basalt eruption started from both Chifeng and Jin- ing districts in 33一28 Ma of Oligocene, and then from southeast to northwest it gradually extended to the southern basalt plateau and the northern basalt plateau in Abaga in turn.It reached cli- max in 11一10 Ma of Middle Miocene, Both Chifeng and Jining districts became dormant in 9-7 Ma of Upper Miocene, and the n， about 4 Ma of Pliocene, the eruption of the northern basalt p1- ateau in Abaga ended up,while the southern basalt plateau did not end-off until 0,33 Ma of Pleistocene. In addition, we have found out about the ages ranging f rom Pliocene to Pleistocene in southern basalt plateau in Abaga, whi- ch may be useful for study of the age of the Quaternary-Ter- tiary boundary.

Abstract:The Yangchuling large一sized porphyry tungsten-molybdenum orefield in the copper-sulfur-iron metallogenic belt of middle and lower reaches of the Yangtze River is genetically and spatially related to the granitic rock body in this orefield, This intrusive body，lying at the connection between the Jiuling upwarping zone of northern Jiangxi and the Lower Yangtze downwarping zone; is a complex rock body formed at the same stage by repeated activities of consanguineous magma and seems to be the product of 3rd stage of early Yanshanian(γ5^2-3).The rocks are intermediate-acid-acid and belong to 4th-5th family of 2nd class in Zavaritskii's classification. Researches show that the principal rock一forming mineral biotite in the ore-forming rock body of the orefield belongs to typical biotite of ferromagnesian series whose Mg-coefficient is close to Fe-coefficient, and is characterized by low F, Cl, Li and high Ti as compared with biotite in the Xihuashan rock body; plagioclase is of transitional-ordered texture whose deg- ree of order is 0.55-O.9,and has well-developed girdle band structure with An being 35-42; the degree of order(δ)of potash feldspar varies in the range of 0.19-0.5, belonging to transitional texture, and Or content is 50-80%。 Studies on typomorphic characteri stics of ore-forming mine rals indicate that the ore-forming rock body in the orefield was formed in a hypabyssal-supergene environment with the material sources characterized by anatexis, and this conclusion is supported by stable isotope and REE data of the ore-forming rock body in the orefield, In genetic type, this rock nody corresponds basically to the synte tic type granite proposed by professor Xu Keqin.

Abstract:The Bailing gold deposit is located in the middle part of the Changjiang fault-fold upwarping zone within the Lower Yangtze syneclise. The gold orebodies, in the irregular veinlike form, occurs in Middle Triassic Tongtoujian Formation. There are two major ore types, namely, oxidized ore dominated by gold -bearing limonite and primary ore dominated by gold-bearing pyrite. The average gold grade of the oxidized ore is 7.8 g/t, whereas that of the primary ore is 7.98 g/t, The gold-bearing minerals are mainly pyrite, limonite, quartz, illite, chalcopyrite etc. By means of ore microscopy, gold analysis of individual minerals, phase analysis, poly-spot analysis and electron microprobe analysis, we have identified the mode of occurrence of gold. Gold minerals are mainly native gold and, less commonly, electrum. Gold is rather fine in granulity and comprises mainly medium-or fine-grained micro-gold. The mosaic types of gold include inclusion gold, gold in intercbystalline pore and fissure gold. Gold has quite high fineness (906.5 on the average) and exists chiefly as minerals.

Abstract:The strontianiferous aragonite reported in the present paper is an aragonitic variety found in Bayan Obo iron ore deposit,Inner Mongolia. It occurs in veined Nb-，REE-bearing dolomitecarbonatite and is mainly associated with dolomite, ankerite,monazite, carbocernaite, pyrochlore, norsethite,calcite, calcios- trontianite, benstonite, zircon, apatite, phlogopite and albite. Strontianiferous aragonite is similar in chemical composition and crystal texture to aragonite, It acquires this name simply on account of its chemical composition and crystal texture. The mineral occurs as a fine-grained aggregate with individual crystal 0.Ol-0.03mm in diameter, transparent, white in color,luster vitreous,streak white, D=3.34, H(vicies)=180-190kg/mm2 (=3 .8Mohe), K=0.32× 10-6C.G.S.M.cm 3/gram. In transmitted light the mineral is transparent and colorless, cleavage no or very imperfect.It is biaxial negative with 2V=9º， Ng=1.6620, Nm=1.6561, Np=1. 5168. X-ray investigation sho;vs that the mineral is orthorhombic，with unit cell values being a=4.91, b=7.89 and c=5.78,The strongest X-ray spacings are 5.39(5)，3.456(10)，3.354( 8)，3.773(7)，2.398( 7).2.016(9)。1.864( 9). Chemical analysis yields the formula of(Ca0.4964 Sr0.4445 Mg0.0114 Ba0.0170 Al0.0007 Fe0.0038 K0.0009 Na0.0063 Mn0.0016 REE0.0066) 0.9892 [(CO3)0.9973 (OH)0.0308]1.0281 with the brief form being (Ca, Sr)CO3.Its DTA curve and infra-red spectrum are similar to those of aragonite.

Abstract:The detrital section method for measuring structural state of potash feldspar on the un iversal stage is developed on the basis of thickening the thin section and selecting the section perpendicular to a-axis and also according to the fact that this mineral has well-developed(100)，(110) and (201) planes. The stability and repeatability of the measurements are quite good. Potash feldspar detrituses in the size of 0.2-0.3mm are chosen as samples to be measureds from them the detrital section fit for universal stage is made up,For the potash feldspar crystals approximately perpendicular to a-axis section, conoscopy or four axis method is used to measure the included angle of 2Y and Ng∧⊥(010) or Ng∧⊥(001) and calculate the optical ordering and triclinity. Practice shows that，as the measurement with detrital section method is simple to operate and has reliable precision, it d.eserves widespread utilization.