地层学杂志

义县地区广义的义县组可解体为王家屯组 (暂命名 )和义县组 ;分属王家屯和义县火山旋回 ,前者为偏酸、偏碱性 ,后者主体为中基性、末期为中酸性火山岩系 ,并广泛发育潜火山岩相的玄武玢岩、安山玢岩和火山集块角砾熔岩筒。该区有七个主要沉积层 ,自下而上分别为王家屯组马神庙层、义县组老公沟层、业南沟层、砖城子层、大康堡层、朱家沟层和金刚山层 ;产有较丰富的无脊椎动物、脊椎动物和植物化石。以砖城子层、大康堡层和金刚山层为界 ,义县火山旋回可划分为 4个亚旋回 ,分别代表火山活动的初始期、主期、晚期和末期。北票四合屯地区的义县组相当义县地区义县组的第一和第二亚旋回 ,含鸟类化石的主沉积层 (尖山沟层和上园层 )可与砖城子层对比

The Yixian Formation (s.l.) can be subdivided into the Wangjiatun (temporary name) and Yixian Formations in Yixian region, Liaoning. All of them belong to the Wangjiatun and Yixian volcanic cycles respectively. The former is the acidic and alkalescent volcanic rocks. The main part of the latter is intermediate basic volcanic rocks. The rocks of the final phase turned into intermediate acidity with widespread subvolcanic facies, including besaltic porphyrite, andesitic porphyrite and agglomeratic brecciated lava pipe. There are seven major sedimentary layers in the Yixian region. They ( from bottom to top) are the Mashenmiao Bed of Wangjiatun Formation, Laogonggou, Yenangou, Zhuanchengzi, Dakangpu, Zhujiagou and Jingangshan Beds of Yixian Formation. It is confirmed that the abundant fossil vertebrates, invertebrates and plants occur just in these strata. The Yixian volcanic cycle can be subdivided into four sub cycles, bounded by Zhuanchengzi, Dakangpu and Jingangshan Beds, representing the initial, principal, late and end volcanic active stages. The Yixian Formation in Sihetun area of Beipiao may be corresponded to the first and second sub cycles of Yixian Formation in the Yixian region. The main depositional layers (Jianshangou and Shangyuan Beds) containing primitive birds in the Sihetun area of Beipiao may be correlated with the Zhuanchengzi Bed in the Yixian region.