Palynology and weathering proxies reveal climatic fluctuations during the Carnian Pluvial Episode (CPE) (Late Triassic) from marine successions in the Transdanubian Range (western Hungary)
Palynology and weathering proxies reveal climatic fluctuations during the Carnian Pluvial Episode (CPE) (Late Triassic) from marine successions in the Transdanubian Range (western Hungary)
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DOI：
10.1016/j.gloplacha.2019.01.018
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发表时间：
2019-06-01
影响因子：
3.9
通讯作者：
Kurschner, Wolfram Michael
中科院分区：
文献类型：
--
作者：
Baranyi, Viktoria;Rostasi, Agnes;Kurschner, Wolfram Michael
晚三叠世早期，卡尼期洪涝事件(CPE)是西特提斯以海相碳酸盐为主的沉积环境中硅质碎屑侵入增多的阶段，其原因可能是气候条件变得更加湿润，大陆径流增加所致。在这里，从孢粉组合和风化指标(α(Al)(1))推断的植被变化研究了匈牙利西部外达努比亚山脉(Tr)的植被变化，以揭示气候变化，并探测湿生植被和加强的大陆水解期。孢粉地层学已被应用于对比西特提斯其他地方已知的碎屑脉冲。定量的孢粉学分析表明，朱利安2期向湿生成分转变，图瓦尔期恢复旱生成分。湿生植被元素的增加与高岭石的抬升相一致，部分与指示朱利安2早期Veszprem组下部陆地径流强烈、大陆水解加剧和气候更加湿润的α值增加相一致。朱利安2组的湿润条件被周期性地中断，表现为碳酸盐台地的进积和泥灰岩单元之间夹层的碳酸盐系列和角砾岩的沉积。在Julian 2末期，湿生植物数量的增加预示着另一次湿润事件，但粘土矿物剖面中高岭石含量的减少和风化指数可能预示着较强的季节性。尽管西特提斯的多重碎屑脉动主要与CPE期间较潮湿的气候有关，但与粘土矿物学和风化指标的比较表明，TRR的情况更为复杂。仅在朱利安2世CPE早期的Veszprem组下部存在与气候湿润相关的大陆风化增强作用。
In the early Late Triassic, the Carnian Pluvial Episode (CPE) is a phase with increased siliciclastic influx into the marine-carbonate dominated depositional setting of the Western Tethys assumingly caused by a shift to more humid climatic conditions and increased continental runoff. Here, vegetation changes inferred from the palynological assemblages and weathering proxies (alpha(Al)(1)) have been studied from the Transdanubian Range (TR), western Hungary to reveal climate variations and detect episodes with hygrophytic vegetation and enhanced continental hydrolysis. Palynostratigraphy has been applied to correlate the clastic pulses known from elsewhere in the Western Tethys. The quantitative palynological analysis indicates a shift towards hygrophytic elements in the Julian 2, and return to xerophytic associations in the Tuvalian. The increase in the hygrophytic vegetation elements is coincident with elevated kaolinite and partially with the increase of alpha-values indicating strong terrestrial runoff, enhanced continental hydrolysis and more humid climate in the lower part of the Veszprem Formation in the early Julian 2. The wetter conditions in the Julian 2 were periodically interrupted by shorter periods of drier climate manifested in the progradation of carbonate platforms and the deposition of carbonate series and breccias interbedded between the marl units. In the late Julian 2 the high amount of hygrophytes points to another humid episode, but the decrease of kaolinite in the clay mineral profile and the weathering indices might suggest stronger seasonality. Although, the multiple clastic pulses in the western Tethys were related primarily to more humid climate during the CPE, the comparison to clay mineralogy and weathering proxies suggest a more complicated scenario in the TR. The enhanced continental weathering related to a more humid climate is only suggested for the lower part of the Veszprem Formation in the early stages of the CPE in the Julian 2.