新疆乌恰早白垩世孢粉植物群及其环境意义

Palynofloras and their environmental significance of the Early Cretaceous in Wuqia,Xinjiang Autonomous Region

基于新疆乌恰地区下白垩统克孜勒苏群51属77种孢子花粉化石的研究,建立了研究区早白垩世早期和晚期两个孢粉植物群。早期孢粉植物群以裸子植物松柏纲松杉目为主,包括掌鳞杉科、松科、罗汉松科、南美杉科和杉科;晚期孢粉植物群的主要成员与早期孢粉植物群基本一致,不同的是掌鳞杉科植物含量大幅度下降。根据孢粉植物群的特征,探讨了该区早白垩世古生态、古气候、沉积环境及古地理意义。研究结果表明乌恰地区早白垩世气候属于亚热带干燥或半干燥型,早期气候温暖干燥,晚期气候暖热半干燥。孢粉学资料显示乌恰地区早白垩世孢粉植物群成员多样,既有来自山地的松杉目植物,又有生长于沼泽湿地的苔藓植物,反映了当时古地理景观复杂多样、植物群落地理分布有明显的垂直分带现象。

Based on the investigations of 77 species of fossil spores and pollen belonging to 51 genera found in the Lower Cretaceous Kizilsu Group in the Wuqia region of Xinjiang Autonomous Region, the early and late Early Cretaceous palynofloras in the region have been established. The early Early Cretaceous palynoflora is dominated by gymnospermous Coniferales, including the Cheirolepidiaceae, Pinaceae, Podocarpaceae, Araucariaceae and Taxodiaceae. The late Early Cretaceous palynoflora is basically similar to that of the early Early Cretaceous, but content of Cheirolepidiaceae decreases sharply. According to the characters of the palynofloras, the Early Cretaceous palaeoecologic, palaeoclimatic, sedimentary environment as well as palaeogeographic significance have been discussed. The results indicate that the Early Cre-taceous palaeoclimate in the Wuqia region should belong to the arid or semi-arid type of subtropic zone, temperate-warm and arid in the early Early Cretaceous and warm-hot and semi-arid in the late Early Cretaceous. The palynological data show that the Early Cretaceous floras are of various origins, including the Coniferales plants from mountain terrene and the moss plants from marsh wetland. The palaeogeography of the Early Cretaceous is characterized by complex and various outlook and the obvious vertical zoning of the plant geographic distribution.