摘要:Hannuoba basalts consisted of tholeiite and alkali-basalt series. The latter contain Iarge amount of type I and minor type II inclusions, and augite and anorthoclase megacryst, which in the extrusive basalts display the characteristics of gravitational and flowage differentiation. The results evaluated from different geothermometers and geobarmeters indicate that the pressures in formation of type I inclusion range from 1.4- 3.1GPa, augite megacryst-2 .i-3.1GPa, basanite 4 magma-3 .1GPa, alk-Ol-basalt magma-2.7GPa, Ol-tholeiitic magma-1.05GPa and Q.-tholeiitic magma-0.45GPa. The fo2 in formation of alk-basaltic magma series vas higher (about 1.1× 10-4-3.8×10-5 atm) than that of tholeiite magma series (about 1.8×10-6-1.6 ×10-7 atm).
摘要:Cishan Migmatitic granite occurs in the Shancaoyu liormation of the Tai- shan Group and extends from NW to SE. The pluton can be divided into three belts from north to south; 1) Porphyric migmatitic granite belt, 2) medium- grained migmatitic granite belt, 3) Moshishan migmatite belt. There are two types of migmatites in the Moshishan migmatite belt; 1) homogeneous migmatite, which had been formed before the formation of the Cishan migmatitic granite, 2) marginal migmatite, which was formed in the course of the pluton emplacement. Homogeneous migmatite inherit chemically biotite leptynite characters. Ho- mogeneous migmatite, medium-grained and porphyric migmatitic granites are chemically same. There are a lot of remnants of biotite leptynite in the homoge- neous migmatite and migmatitic granites, and there are systematically changing of zircon traits and accessory mineral associations in these rocks mentioned above. It is suggested that homogeneous migmatite is formed from biotite leptynite by migmatization, Cishan pluton is formed from homogeneous migmatite by me- ping under closed system conditions, and the microcline porphyric crystal in porphyric migmatitic granite is formed in the later of the magma evolution.
摘要:The paleomagpetic polar coordinates of Tushun basalts, infered by their paleoma}nitic data, are as follows: 1st phase of basalt; 258.1ºE, 76.8ºN(+) 2nd phase of basalt: 150ºE, 44.7ºN(一) The latter is similar to that of early Tertiary in Sibiria (152ºE, 57ºN-) and that of Early Cretaceous in Western Laioning (148.9ºE, 65ºN-).This sug- gests that the magnetic polar or Sino-Korean platy may have been only a little motion in the period of Cretaceous to Paleccene. The average isotopic age of basalt defined from 9 samples is about 64士5Ma and the K40-Ar40 isochoren age is 66.2士2Ma. Tn addition, 12 dating basalts from aialiaohe have an average K- Ar age of 71.5士8Ma. These data indicate a strong eruption of basalt and crustal tension in the period of Latest Cretaceous-Early Paleocene, which may be held as indicative of development of rift. The basalts are petrologically possessed of transitional feature between con- tinental and ocean tholeiite and belong to basalts of rift type. The basalts are saturated or lightly unsaturated with SiO2 and have FeO*/Mg0 ratio of 1.3 to 1.6, with average Ti02 content of 1.89. These rocla are increased gradually in alkalis from 1.36 in Fushun basalts to 1.63 and 1.81 in the Mesozoic basalts located in western Liaoning and Dashinganling respectively. The REE data of these rocks also demonstrated their rift nature (rich in light PEE).The crustal thickness in this area, calculated by Rb/Sr ratio (Condie 1976)，is about 30士2 kilometers which correspond completely with geophysic data. In Dashinganling, however, the thickness of crust may be up to 38-40 lcilome- ters. The fact descriptive above indicated an intensive crustal tension in this area. In summary, the eruption of basalts in Bohai-Xialiaohe-Fushun area at the time of Latest Cretaceous to Early Paleozene represented a new stage of Tancheng -L ujiang Fault developing into a rift.
摘要:The quartz grains affected by outer environments in the processes of transport and sedimentation must be left some marks on their surfaces. The different sedimentary environments may have made the quartz grains different in shapes and surface characteristics. The sample, taken from three Tertiary sedimentary facies in Kuqa Basin, Xinjiang, are possessed of their own surface characteristics. The quartz grains from the lake facies commonly have on their surfaces silica precipitation and dish-shaped concavities, which represent desert environment,and the solution pits formed by later chemical corrosion,The quartz grains in the river facies generally have charactev0istics typical for underwater -ranport-V-form pit、Because of weakening of the waterpower, we can also observe the silica precipitation and secondary quartz crystal on their surfaces. In the littoral facies the quartz grains exhibied the laminated and stepped cleavabes, or solution brooves and pits as a result of the mechanical and chemi- cal corrosion.
摘要:The metamorphic rocks of the Bainaimiao Group in Bainaimiao Copper Mining District have been metamorphosed to amphibolite facies and greenschist facies, The amphibolite facies consists mainly of leptite, gneiss, blastobandcd amphibolite and non-blastobanded amphibolite. The greenschist facies is composed largely of relict phenocryst-bearing actinolite plagioclase schist and non-phenoc- rystal actinolite plagioclase schist with intercalated chlorite-plagioclase schist. Through studies of their relict textures and REE patterns, both the amphi- bolite and greenschist can he divided into ortho- and para-types. The protoliths of the relict phenocrystal actinolite plagioclase schist and non-blastobanded amphibolite were basic lavas, while those of the non-phenoc- rystal actinolite plagioclase schist and blastobanded amphibolite were tuff or layered tuff.
摘要:(1). This paper involves some of the concepts of modulated structures and complex structures of alkali feldspars and their experimental methods. Complex structures such as density modulation, periodic twinning and cohe- rent exsolution etc. were found in alkali feldspars of Hanmuoba basalt, Zhangjia- kou, Hebei Province, and in the volcanic elastic rocks of northeastern Jiangxi Province. X-ray single crystal analysis methods such as precession method, standard orientation oscillation, Weissenberg method and transmission electron microscopy (TEM) were employed to reveal these complex structures of alkali feldspars, and the techniques are outlined in this paper. (2). the Hannuoba Basalt is located in the northwestern part of Zhangjiakou, Hebei province. The distribution of basalt is controlled mainly by the two fractures in the area. Several kinds of deep-source、inclusipns and megacrysts such as feldspars and pyroxenes were found in the basalt. For about sixty years，all the feldspar megacrysts found in this area had been regarded as anoithoclases.On the basis of anaIysis of compositions, optical properties and X-ray diffraction patterns， oligoclase-andensine megacrysts were first discovered by the author in Zhangjiawan Tholeiite Grater in the area. The structure of an andesine megacryst in it has been determined. The least-squres refinement led to a final discrepancy index R0.096.The bond lisngths of T-O tetrahedrons and A1 occupancy indicate that Al/Si distribution is disordered. (3) The paper is concerned with the anorthoclase rnegacrysts collected from Damaping Volcanic Cone, Zhangjiawan Lava Sheet and Taoyaowan Pipe in Han- nuoba Basalt, which are all alkali basalt. The study is focused on the complex structures of the anorthoclase megacrysts and was carried out mainly by means of single-crystal diffraction in addition to the powder X-ray diffraction, chemical analysis and optical study. The anorthoclase megacrysts from Damaping are cha- racterized by their simpler structures. Only albite law or pericline law twinning can be found on the ;single diffraction patterns. The same patterns of anorthoclase megacrysts from Taoyaowan Pipe are characterized by bond satellite diffractio.ns, which are . caused by density modulation structures. The direction of its wave tran- smition is nearly parallel to the normal of (10 0 1) and the length is about 100A.Several kinds of complex structure diffractions including coherent decom- position (cryptoperthite) and long-period albite twinaing (transverse modula- tion structure) were found on the patterns of, the anorthoclase megacrysts from Zhangjiawan Lava Sheet. The period of the transverse modulation is 17 to 18b. An anorthoclase crystal structure has been determined. The least-squares refinment}led to avfinal discrepancy index R=0.072. The bond lengths of T-O tetrahedron indicate that the structure is almost topochemically monoclinic sym- metre.
摘要:The author introduces a new method (five, axis-twin method) for direct me- asuring of the angle C∧Ngmx, of clinopyroxene on the universal stage. The me- asuring procedure is as follows: 1)selecting some mineral grain; with twinning plane (100) in plane-law twin and putting them in the center of the universal stage; 2) turning N-axis and making it parallel to the longitudinal line; 3) tilting H-axis and making the composition plane of twin coincide with the up- right plane of longitudinal line; 4) setting M-axis at angle 90º for K┴I, and putting plane (O10) of the principal optic axis on the S-N upright plane, so Nm(1,2) coincide with the 1-axis; 5) tilting alternately K-axis and 1-axis, and making successively Np1 Np2 (or Ng2)，Ng1Np2`, and Ng1Ng2 coincide with the K- axis, meanwhile, writing down the readings of 1-axis while the axis of each indicatrix coincides with K-axis; 6) according to the readings on the graduated wheel of 1-axis, calculating the angle of Ng1∧Ng2, then (N1∧Ng2) /2 =C∧Ng. The above-mentioned method widens the application range without the aid of stereographic projection.
摘要:Native arsenic is known as a rather rare mineral. 'The native arsenic under study, appearing in compact massive form, was found in the carbonate veinlets within tungsten-bearing quartz veins. The chemical composition obtained from electron microprobe analysis is 99.26% As, 0.02%S, 0.01%Fe, 0. 01%Ni, 0.07%Ag, 0.03%Sb, 0.03%Al, 0.04%Cd, totalling 99.45%· That the native arsenic is liable to oxidize is shown by the fact that the tin-white colour of a fresh fracture with metallic luster may gradually change to dark-grey when exposed in air.SEM observation shows the native arsenic appear in the form of tabular crystals. The reflectivities (λ, R) are, 470nm, 50.4; 480nm, 48.2;546nm, 47.8; 654 nm, 45.7，VHN20g=132. 5kg/mm2. The strongest lines in X-ray analysis are; 2.772 (10)，3.531(7)，2.053 (5) 1.881(4)，1.556(4).