辽西义县组中淬碎熔岩的发现及其意义
DISCOVERY AND SIGNIFICANCE OF THE QUENCH FRAGMENT LAVA IN YIXIAN FORMATION IN WESTERN LIAONING PROVINCE
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摘要: 通过近年在辽西北票-义县地区的研究,在该区首次发现了多处湖盆环境水下急速冷却机制形成的淬碎熔岩(不同于一般的枕状熔岩),这些淬碎熔岩分别与义县组中不同层位的沉积夹层伴生,其就位年龄应分别代表着相应沉积夹层的年龄.淬碎熔岩分布的主要层位是在北票义县组四合屯(尖山沟)沉积层的上部,义县地区义县组砖城子沉积层的中部、大康堡沉积层上部.即出露于北票四合屯观察哨南侧,义县金家沟、腰马山沟、二道河子、上下崔家沟、陶西沟北部、大康堡地区.本淬碎熔岩的发现及其进一步深入研究,将为解决一直争论中的北票地区义县组和义县地区义县组的对比问题提供依据,还将为进一步正确厘定义县组的范畴、火山活动规模和火山岩层的厚度,探讨义县地区义县火山旋回主喷发期跨越的时限,进而为探讨辽西地区主体引张作用的时限提供重要证据.Abstract: During recent years' geologic study in Western Liaoning, the authors found broadly outcropping quenching pillow lavas formed in lake basin environment for the first time. The quenching fragment lavas are distributed in the upper part of Sihetun layer, the middle of Zhuanchengzi layer and the upper of Dakangpu layer of Yixian formation. They commonly occur associating with the sediment interbeds of different levels in the Yixian formation, thus their emplacing ages would represent those of the corresponding sediment interbeds. The discovery of the quenching pillow lava is significant in the study of evolution and volcanic-sedimentary activities of Yixian-Fuxin basin and Jinyang basin.
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