黑龙江省东部鸡西盆地早白垩世穆棱组植物化石新材料

系统描述了最近采集的穆棱组植物化石22属23种，其中的两种被子植物叶化石均为具原始被子植物叶特征的小型叶，在该植物群中尚属首次发现。运用扫描电镜(SEM)等方法对其中的Tyrmia sp．，Nilssoniopteris sp．，Ginkgoites cf．．sibirica，．Sphenobaiern sp．，Elatocladus manchurica等化石的叶角质层进行了研究。据已有的资料统计，穆棱组迄今已知有化石植物31属38种。该植物群以真蕨类占据绝对优势，裸子植物也相当丰富，其中的大多数种类主要见于早白垩世，穆棱组的地质时代应属早白垩世巴列姆期或巴列姆-阿普梯早期。植物组合中以丰富的热带及亚热带型植物为主要特点，未发现针叶类型的植物，说明早白垩世穆棱组沉积时，该地区的气候温暖湿润；另一方面，落叶的银杏类和松柏类，以及裸子植物木化石中具有清楚的生长轮，又说明该地区的古气候存在着季节变化。该植物群属于早白垩世西伯利亚植物区或加拿大-西伯利亚植物区。

NEW MATERIAL OF FOSSIL PLANTS FROM THE EARLY CRETACEOUS MULING FORMATION OF THE JIXI BASIN, EASTERN HEILONGJIANG PROVINCE, CHINA

The Early Cretaceous flora from the Muling Formation of the Jixi Basin, Heilongjiang Province, Northeast China comprises 38 species, so far as known, belonging to 31 genera of high plants, of which 23 species of 22 genera are described here. The angiospermous leaves Asiatefolium elegans and Dicotylophyllum sp. are found in the Muling Formation for the first time. Cuticles of Tyrmia sp., Nilssoniopteris sp., Ginkgoites cf. sibirica, Sphenobaiera sp., Elatocladus manchurica are studied with scanning electron microscope (SEM). The flora is mainly composed of leptosporangiate ferns and gymnosperms. Most of them occurred in the Lower Cretaceous. The geological age of the Muling Formation and its flora may be Barremian and probably middle Barremian-early Aptian. No representatives of gymnosperms with needle-like leaves have been found in this flora. The occurrence of abundant tropical- or subtropical-type ferns implies a warm and humid climate dominating over the area. On the other hand, some deciduous gymnosperms including Ginkgoales, and the presence of growth rings in the fossil secondary wood, indicate seasonal changes. Paleophytogeographically, the flora belongs to the Early Cretaceous Siberian or Canada-Siberian province.