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961.
Two examples are given for comparing applications and limitations of four methods which can be used to deal with error propagation in geochemical calculations.The examples indicate that the Monte Carlo method can also be employed to evaluate the effect of covariance.A special function of the method for covariance matrix shown here can reveal the correlations of middle variables relative to the independent primary variables. 相似文献
962.
The Shexian gneissic granodiorite in southern Anhui trends NE 55° from Shexian in the west to Guitoujian in the east with
a length of 22 km and an outcrop area of 32 km. It was considered formerly to be Caledonian on the basis of a biotite K-Ar
age of 474 Ma (1982). However, new evidence indicates that it may be Early Jinning in age as shown by: (1) it is found intruding
into the Mid-Proterozoic Shangxi Group and is unconformably overlain by the Sinian Xiuning Formation, and (2) a zircon U-Th-Pb
age of 928 Ma is obtained for the pluton.
The pluton is composed of plagioclase (An=27.37%), K-feldspar(14%), biotite(16%) and quartz(32%). Accessory minerals are ilmenite
(150g/T), xenotime (15g/T). garnet(25g/T), monazite(10g/T), zircon (20g/T) and apatite (104g/T). Petrochemical characteristics
of the intrusion are:(l) Al-enrichment (A/NKC=1.30); (2) H2O enrichment (H2O= 1.74%); and (3) low oxidation index (f ’=0.10). It belongs to the continental crust transformation type as evidenced by: (1) MF and Mg/Y values of biotite are 0.41
and 0.31 respectively; (2) (87Sr/86Sr)=0.71119; (3) δ Eu=0.52; and (4) A/NKC=130. The Shexian pluton is therefore considered as a product of melting of phyllite
at depth in the light of similarities in trace element and REE contents with the phyllite of the Banxi Group. Calculations
of REE batch partial melting indicate that it may have resulted from 75% melting of the Banxi phyllite. 相似文献
967.
本文通过都庞岭北部地区沟系土壤测量找金实例,表明在通行不便的特殊景观区采用沿河、沟谷西侧采集地球化学土壤样,可以取得较好的找矿效果。探讨了沟系土壤测量的应用条件、布样方法等,供进一步研究和探讨。 相似文献
968.
The Baishitouquan amazonite and topaz-bearing granite is one of the typical high-rubidium and high-fluorine granites in the
eastern part of the Mid-Tianshan belt. This intrusion is in sharp contact with Mid-Proterozoic schists, gneisses and marbles,
and is composed of four zones transitional from the bottom upwards: leucogranite, amazonite granite, topaz-bearing amazonite
granite and topaz quartz albitite.
The Baishitouquan granite contains highly ordered K-feldspar, Li-rich mica, Mn-rich garnet, α-quartz and low temperature zircon
and is chemically high in Si, K, Na, Al, Li, Rb, Cs and F, and low in Ti, Fe, Ca, Mg, P, Co, Ni, Cr, V, Sr and Ba, with Na2O<K2O. Amazonite from the amazonite granite zone contains 1867 ppm Rb. The F contents of bulk rocks are 3040 and 4597 for the
amazonite granite and topaz-bearing amazonite granite zones, respectively. These two zones have δ18O values of 8.97–9.85‰ (SMOW) and show flat REE distribution patterns with strong Eu depletion. K-Ar and Rb-Sr ages of this
intrusion are 226. 6 Ma and 209. 6 Ma respectively, with an initial87Sr/86Sr ratio of 0.987±0.213.
The Baishitouquan granite is the product of crystallization of a low temperature, and water, rubidium and fluorine-rich magma,
which may have been derived from partial melting of muscovite-rich crustal rocks. Consolidation of this granite involved two
contrasting and successive stages: melt crystallization and hydrothermal metasomatism and precipitation. Various geological
features of this granite were formed during the transition from the magmatic to the hydrothermal stage. 相似文献
969.
矾山磷铁矿床属磁铁磷灰石型岩浆晚期堆积矿床。可分为四种主要矿石类型,即磁铁磷灰石岩型、磷灰石岩型、磷灰石黑云母辉石岩型和正长黑云母辉石岩型。它们不但在矿石结构、构造、矿石化学成分和P2O5品位等方面各有其特征,而且P2O5和TFe含量的相关性也不同.其中在磁铁磷灰石岩型矿石和正长黑云辉石岩型矿石中二者呈显著正相关关系,而在其余两类矿石中则呈负相关关系。 相似文献
970.
阿舍勒铜锌矿床原生晕和次生晕均受矿体、中泥盆统阿舍勒组第二岩性段地层、近SN向一断裂控制。阿舍勒铜锌矿床的成矿、成晕作用是多期次的,其成矿、成晕直接(矿体)指示元素为Cu,Pb,Zn,Au,Ag,Ba等。前晕指示元素为As,Sb,Hg等;尾晕指示元素为Sn,Mo等。利用这些异常元素的地球化学特征,不仅可确定该矿床的矿化类型和矿体剥蚀深度(或埋深),而且也可确定与该矿床相似的成矿靶区(即异常区),并对成矿靶区进行预测评价。 相似文献