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浙江江郎山丹霞地貌发育的年代与成因
Age and Genesis of the Danxia Landform on Jianglang Mountain, Zhejiang Province
【摘要】 江郎山位于华南褶皱系、江山—绍兴深断裂和保安—峡口—张村断裂带之间。白垩纪早期这两大断裂的拉张断陷导致峡口盆地的形成,随之主要有下白垩统永康群馆头组(K1g)、朝川组(K1c)和方岩组(K1f)在盆地中的沉积。白垩纪晚期上述两大断裂发生强烈挤压活动,峡口盆地逐渐隆升。新生代以来,峡口盆地在构造抬升中,产生大量张断裂和节理,加速了对岩体的切割,以及岩体被切割后的崩塌,导致了丹霞地貌的发育。江郎山丹霞地貌申报世界自然遗产的主要依据是其特有的壮观而独特的老年期孤峰—巷谷以及生动而逼真的象形石丹霞地貌特征、独特的地台活化现象与重要的岩石学科学研究意义以及该区特有的重要事件地层学和古生物学研究的科学意义。本文根据对江郎山亚峰垂直贯穿于丹霞地貌岩层永康群中辉绿岩脉标本K-Ar法的测年,揭示了当地峡口红层盆地抬升的时代为晚白垩世77.89±2.6MaBP(K2),这也是我国目前丹霞地貌研究中所测得的可靠年代学数据。
【Abstract】 The Jianglang Mountain is situated at the transitional zone of South China fold-system, Jiangshan-Shaoxing deep rip belt and Baoan-Xiakou-Zhangcun rip belt. The formation of the Xiakou basin was a result of the tensioning of the above mentioned two rips in early Cretaceous, afterward, series deposits such as Guantou formation (K1g), Chaochuan formation (K1c) and Fangyan formation (K1f) which belong to Yongkang group, lower Cretaceous phase, were gradually built, whilst the rips occurred to extrude and the basin began to rise in late Cretaceous. Meanwhile, amounts of tension fissures and joints have been produced since Cenozoic, accelerating down-cutting velocity in base rock. Consequently, landform-building activities such as weathering, eroding and collapsing etc. were prevalent as finally to develop the Danxia landform. The main sceneries to apply for world natural relics are relying on unique and unparalleled peak, split valley with vivid stones and reviving of platform. What is more, it is significant to study lithology, stratigraphy and paleo-biology. According to dating for specimen of dolerite vein through the Yongkang group of Mt. Yafeng by K-Ar method, this article revealed the uplift age of red-bed basin to be 77.89±2.6 Ma BP (K2), i.e., late Cretaceous, the first chronological datum of Danxia landform research in China.
【Key words】 Zhejiang; Jianglang Mountain; Danxia landform; landform development; landform genesis;
- 【文献出处】 地理学报 ,Acta Geographica Sinica , 编辑部邮箱 ,2009年01期
- 【分类号】P931
- 【被引频次】61
- 【下载频次】1748