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钾霞橄黄长岩是一种产于大洋和 /或大陆环境 ,尤以大陆裂谷最为多见的超钾质火山岩 ,也是世界上出露最少的火成岩之一 ,目前世界只有少数几个国家和地区有这类岩石的报道。甘肃西秦岭新生代火山岩是我国目前唯一有报道的钾霞橄黄长岩产区。本文详细介绍了西秦岭新生代钾霞橄黄长岩及深源包体的岩石学特征 ,提供了该区 13个岩体 30个具代表性的全岩化学和主要矿物的化学成分分析结果 ,6个具代表性的Sr,Nd,Pb同位素分析结果 ,以及 2个火山岩全岩 Ar/ Ar同位素定年结果。研究表明西秦岭新生代钾霞橄黄长岩主要是中新世火山作用的产物。火山岩的化学成分贫 Si O2 和 Al2 O3,富 Mg O,Ca O,Ti O2 和 (K2 O+Na2 O) ,以及具有高的 [Mg O]值 (平均大于 6 8)和 Ni O含量 (平均在 0 .3%以上 )。火山岩中含有丰富的深源包体 ,岩石的结晶程度很差。所有这些表明西秦岭存在原生钾霞橄黄长岩浆。而且本区钾霞橄黄长岩与碳酸岩密切共生 ,显示了典型的大陆区钾霞橄黄长岩的特征。火山岩的Σ REE在 36 5× 10 - 6 ～ 6 4 9× 10 - 6 之间 ,其中轻稀土总量 (Σ L REE)达 319× 10 - 6 ～ 5 6 9× 10 - 6 ,尤以强烈富集大离子轻石元素 (K、 Rb、 Sr、 Ba)和相对亏损高场强元素 (Nb、 Ta等 )为特征。火山岩具有相对高的 1 43N
Potassium Xiagulin is a type of ultra-potassic volcanic rock that is most commonly found in oceanic and / or continental environments, especially in the continental rift. It is also one of the least exposed igneous rocks in the world. At present, there are only a few countries and regions in the world There are reports of such rocks. The Cenozoic volcanic rocks of West Qinling in Gansu Province are the only reported Kashu Paleo-Huangchang rock producing areas in China. In this paper, the petrological characteristics of the Neozoic kaxilian palaeobitite and deep-sourced inclusions in the West Qinling Mountains are introduced in detail. The chemical composition analysis of 30 representative whole-rock chemistry and major minerals of 13 intrusion bodies is provided. Six The results of isotopic analysis of Sr, Nd and Pb, and the Ar / Ar isotopic dating of the two volcanic rocks. The research shows that the Neozoic kaxilian palygorskite in the West Qinling is mainly the result of the Miocene volcanism. Volcanic rocks are chemically depleted in Si02 and Al203, rich in MgO, CaO, Ti02 and (K2O + Na2O) and have high [MgO] values (on average greater than 68) and NiO content Above 0.3%). Volcanic rocks are rich in deep-sourced inclusions, the degree of crystallization of the rock is poor. All of these indicate that there are primary karst kyanites in West Qinling. In addition, the karst palygorskites coexist closely with carbonate rocks in this area, showing the typical characteristics of the karst kyphotic pluton in the continental area. The Σ REEs of volcanic rocks range from 36 5 × 10-6 to 6 4 9 × 10-6, with the total amount of light rare earths (Σ L REE) reaching 319 × 10-6 ~ 5 6 9 × 10-6, The enrichment of large ion light rock elements (K, Rb, Sr, Ba) and relatively depleted high field strength elements (Nb, Ta, etc.) are characterized. Volcanic rocks have a relatively high 1 43N