摘要
本研究报道了产自喜马拉雅山脉中段卓奥友峰上新统加布拉组的植物大化石组合,共鉴定出植物类群13科17属19种,包括蕨类植物1种,裸子植物2种,被子植物16种.加布拉植物群植物生活型丰富,包括乔木(云杉属、柏木属、桤木属和杨属)、灌木(小檗属、锦鸡儿属、枸子属、花楸属、金露梅属、沙棘属、杜鹃花属和忍冬属)、陆生草本(木贼属、蕨麻属和委陵菜属)、水生草本(眼子菜属和水毛茛属).研究表明,当时该地区的植被以云杉针叶林为主,同时表现出植被分布的垂直地带性,在云杉林上方生长着耐冷干的金露梅属、锦鸡儿属等高山灌丛,下方为相对喜暖湿的桤木属等阔叶乔木.加布拉植物群的面貌与现今该地区以高寒草甸为主的植被面貌截然不同,表明上新世以来该地区经历了明显的气候改变和植被演替.植物组合的特征显示,上新世喜马拉雅山脉中段的气候较现今更为温暖湿润,随着喜马拉雅山脉的持续抬升和高原干旱化进程的加剧,导致该地区的植被由以暗针叶林为主转变成现今的高寒草甸.
Abstract
This paper describes a plant macrofossil assemblage from the Pliocene strata of the Jiabula Formation,which is a lacustrine deposite,located on Mt.Cho Oyu in the central Himalaya(28° 28′ 1 2″N,86°58′64″E),enhancing our understanding of the region's paleoclimate and paleovegetation.Fieldwork conducted in 2023 collected 533 fossil specimens from two stratigraphic sections,and the measured thicknesses are 32.5 m and 35.25 m respectively within the Jiabula Formation.These specimens,encompassing various plant parts(branches,leaves,seeds,fruits,etc.),were identified using detailed morphological comparisons with extant relatives.The Jiabula flora comprises 19 species across 17 genera in 13 families,including Equisetum,Picea,Cupressus,Potamogeton,Berberis,Batrachium,Caragana,Argentina,Cotoneaster,Sorbus,Potentilla,Dasiphora,Hippophae,Alnus,Populus,Rhododendron,Lonicera.The fossil assemblage reveals a Picea-dominated landscape,with a variety of life forms,from coniferous trees and broad-leaved angiosperms to shrubs and herbaceous plants suggesting a forested landscape with distinct vertical vegetation zonation.Cold-tolerant alpine shrubs likely dominated higher altitudes,while warm-temperate taxa occupied lower elevations.The fossil evidence reveals a Pliocene landscape with vertically zoned vegetation,reflecting a warmer and wetter climate than that of the present.The rediscovery of diverse taxa within the Jiabula flora underscores the role of climate and topographic uplift in shaping the region's vegetation history.The vegetation patterns indicated by the Jiabula flora differ markedly from present-day alpine meadows in the region,highlighting significant climatic shifts since the Pliocene.Additionally,the presence of morphologically diverse,cold-and drought-resistant genera such as Caragana and Dasiphora suggests that the region was already experiencing aridification due to the uplift of the Himalayas.These findings align with other paleobotanical studies from adjacent areas,indicating a progressive shift from warm-temperate coniferous forests to the cold-adapted alpine meadows seen today,influenced by the uplift of the Himalayas and the intensification of aridification.
维普
万方数据