【摘要】 辽西建昌-凌源地区早侏罗世水泉沟组底部英安岩中斜长石和角闪安山岩中的角闪石具有环带结构。对斜长石用电子探针分析方法研究,发现较完整的斜长石晶体是由具反环带特征的核部和5个具正环带特征的振荡环带组成,核部与振荡环带之间存在熔蚀面。采用相图和晶体环带样式理论分析得出,核部的反环带指示岩浆中无水矿物结晶使岩浆房中的P_H2O增大,熔蚀面代表了 P_H2O增大到某一临界值导致岩浆房上覆围岩破裂,5个振荡环带反映岩浆房上覆围岩破裂后在岩浆房中心和边缘之间岩浆发生过强对流并最终喷出地表。具环带结构的角闪石的结晶压力（核部（5.8±0.5）×10⁸Pa,边部（4.8±0.5）×10⁸ Pa）说明,岩浆房的深度为17.5±1.8km,岩浆房开放前流体超压达到过1×10⁸ Pa 左右。推断,辽西建昌-凌源地区早侏罗世早期地壳岩石圈上部处于压应力状态,下部处于张应力状态。更多还原

【Abstract】 Zoning textures are well developed in plagioclase phenocrysts of dacite and amphibole phenocrysts of amphibole andesite at the bottom of Shuiquangou Group,which had erupted in Earlier Jurrasic in Jianchang-Lingyuan Area of Liaoning Province.Using electron probe analyses methods （BSE image,element scan in line,quantitative point analyses）,it is recognized that zonings of the plagioclase are separated into a core with reversed zoning and five normal oscillatory zonings by a resorption surface.Magma chamber process is got by studying in phase graph and with theory of zoning patterns.Crystallization of the no-water-containing minerals brought P_H2O going up,which made the country rocks above magma chamber broken when P_H2O reached a critical value.Resorption surface represents the break of the country rocks;and the five oscillatory zonings represent the intense convection of magma in magma chamber subsequently.The pressure conditions where amphibole phenocrysts crystallized （（5.8±0.5）10⁸ Pa in core,（4.8±0.5）10⁸ Pa at the rim） indicate that depth of magma chamber was 17.5±1.8km and the exceeding pressure of fluid was about 1×10⁸Pa.It is concluded that the upper part of crust-lithosphere was under compressive stress but the lower part was under tensile stress,and the state of the crust-lithosphere may be a syncline in lithosphere scale.更多还原