中文摘要：

唐藏石英闪长岩体出露于北秦岭造山带西段，侵入于丹凤群火山-沉积岩系之中，主要矿物组成为斜长石、角闪石、石英、钾长石、黑云母等，形成时代为454Ma。该岩体SiO2=62．02％～64．26％；Al2O3=16．55％～17．45％，MgO=1．71％～2．09％，Sr=（1069-1296）×10^-6（〉400×10^-6），Y=（11．6～13．81）×10^-6（〈18×10^-6），Yb=（0.96～1．14）×10^-6（〈1．9×10^-6），Sr／Y=80．98～108．19（〉40），稀土总量（∑REE=217．88×10^-6～355．07×10^-6）较高，LREE强烈富集，重稀土亏损，Eu负异常不明显（LREE／HREE=17．72～25．82；LaN／Yb74=44．56～53．85；δEu=0．82～1．0），显示出典型埃达克岩的岩石地球化学特点。在以原始地幔标准化的微量元素分布图中，大离子亲石元素（LILE）K、Th、Rb、Ba、Sr等富集，高场强元素（HFSE）Ta、Nb、Y、Yb等较相邻元素相对亏损，微量元素曲线分布形式及稀土元素配分模式与典型地区埃达克岩分布形式一致。研究表明，该岩体Na2O=4．99％～6．91％，Na2O-2〉K2O，Mg#=0．59～0．63，A／CNK=0．82～1．01，σ=4．24～2．24，为富钠偏铝质高镁埃达克岩。唐藏埃达克岩体岩浆源于早古生代秦岭商丹洋向北俯冲消减洋壳板片的部分熔融，岩浆在上升过程中与地幔楔发生反应。北秦岭早古生代埃达克岩的确定为探讨秦岭早古生代构造演化提供了新的证据。

英文摘要：

The Tangzang quartz diorite pluton, distributed in the western part of North Qinling and intruding into the voleano sedimentary roeks of Paleozoie Danfeng Group, is eonsist mainly of plagioelase, amphibole, quartz, alkali feldspar and biotite with the form age of 454Ma. Major and traee elements studies show that the pluton is eharaeterized by typieal adakite features with SiO2=62.02%～64.26%;Al2O3=16.55%～17.45%,MgO=1.71%～2.09%,Sr=（1069-1296）×10^-6（〉400×10^-6）,Y=（11.6～13.81）×10^-6（〈18×10^-6）,Yb=（0.96～1.14）×10^-6（〈1.9×10^-6）,Sr/Y=80.98～108.19（〉40）, enriehed LREE and depleted HREE, laek negative Eu anomalies（LREE/HREE17.72～25.82;LaN/Yb74=44.56～53.85;δEu=0.82～1.0）. Primitive manlte normalized traee elements patterns reveal that LILE （K,Th, Rb, Ba, Sr） is enriehed, but HFSE （Ta, Nb, Y, Yb） are depleted eompared with adjaeent elements, whieh is similar to that of typieal adakite. The researeh also showed that the pluton is eharaeterized with f Na20 （4.99%-6.91%）, Na2O〉K2O, Mg# （0.59-0.63）, A/CNK（0.82-1.01） and σ（4. 24-2.24）, suggesting that the Tangzang quartz diorite pluton belongs to Na-rieh, magnesium adakitie roeks. Parent magma of the adakitie roeks originated from partial melting of the subdueted oeean slab of the Qinglin Shangdan oeeanie plate toward north, and reaeted with the mantle when twhen the magma was aseending. The diseovery of the Tangznag adakitie roeks in the west segment of North Qinling provides new evidenee for studying Paleozoie teetonie evolution in Qinling Mts.