【摘要】 <正> 中国东部新生代火山岩分布甚广,大部隐伏于地下(图1),在环太平洋火山岩带中占有重要位置;对研究岩石圈的组成、结构、发展、演化和板块构造均起着重要作用。虽早在50年代就有专文对其进行探讨,但长期以来在这方面的工作进展不大;只近些年来,对中国东部新生代火山岩及有关超镁岩包体的研究有了较大的发展,已积累了较多资料,现以作者更多还原

【Abstract】 Eastern China is a composite petrological area of Cenozoic volcanic rocks. Here the volcanic rocks of the tholeiite series, calc-alkali series,Hy-norm bearing olivine basalt series, Na-alkali series and K-alkali series coexist. Eastern China can be divided into the northern and southern petrological regions by Changzhou-Yueyang old deep fault.The magma generation and magmatic activities in the northern region were controlled by the mantle uplift and the old deep faults (such as the Lujiang-Tancheng-Shenyang-Mishan, Nenjiang-Taihang Mt., Chicheng-Jianping, Zhangjiakou-Tianjin,Lower Yangtze deep faults.) These old deep faults were revived and some of them were changed into rifts and fault basins due to back-arc expansion caused by sustained mantle uplifting. The Bohai Sea Basin is situated at the intersection of the Lujiang-Tancheng-Shenyang-Mishan and Zhangjiakou-Tianjin uplifting belts of upper mantle, making use of these li- thospherie weakness since Paleocene or early Eocene time. Here the thinnest crustal thickness is less than 30 km, the depth of the top of asthenosphere is about 50 km and the high value of heat flow reaches to 2.36 HFU.The asthenosphere surface has an asymmetric conical form, taking the Bohai Sea Basin as its apex and with steep slope to the south, east, west and gentle slope to the north. The Northern Jiangsu Basin is situated above another smaller mantle uplift. Some Eogene (71.5—28.5Ma)tholeiites are mainly located at the central part of the mantle’s upwarping; well developed Neogene (23.8—2.6Ma)alkali olivine basalts are distributed at the outer lane of the former and the Quaternary (1.48 Marecent) peralkali volcanic rocks are far away from them. These features are especially clearly seen along Lujiang-Tancheng-Shenyang-Mishan, Nenjiang-Taihang Mt., Zhangjiakou-Tianjin deep faults. The Quaternary volcanic rocks are more complicated and can be subdivided into three rock series: 1.Na-alkali rock series: alkali olivine basalt, phonolitic basanite, olivine nephelinite; 2.K-alkali rock series: leucite-bearing alkali trachyte, leucite phonolite, tephritic phonolite, tephritic leucitite, olivine leucitite. 3. Hy-norm bearing olivine basalt series: oli vine basalt, quartz latite, quartz alkali trachyte, pantellerite。The studies of incompatible elements and REE show that the Eogene tholeiitic rocks were derived by 5.0—8.0%melting of a garnet lherzolite; the Neogene alkali basalts—4.0—5.0%; and the Quaternary peralkali volcanic rocks (phonolitic basanite,nephelinite)—0.7—1.0%.The volcanic rocks of the K-alkali series were derived by 0.7—1.5% melting of a phlogopite lherzolite.At the same time, these studies also show that the degree of enrichment of incompatible elements and LREE increases with decreasing age, increasing source depth and decreasing degree of melting of the upper mantle. This presumably is an indication of a waning magmatic hearth with gradually decreasing temperature, accompanied with the down-cutting of the lithospheric faults. We call such features as "a reverse process of magma generation". And the opposite features of magmatic evolution of the East African Rift in Kenya can be called as "a positive process of magma generation"。The situation in the southern region is comparatively simple. The generation and distribution of basalts are mainly controlled by the plate subduction and by a group of deep faults (such as Ninghai-Wenzhou-Changle-Zhaoan-Shantou, Shangyu-Lishui-Minqing-Haifeng and Shaoxing-Mingxi-Changding-Heyuan old deep faults).The east, intermediate, west volcanic rock belts consist mainly of thoIeiite, alkali olivine basalt and phonolitie basanite respectively. These original basaltic magmas were resulted at the subduction zone of the Pacific Plate by partial melting of the mantle at different depth。更多还原