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Weathering and paleoprecipitation indices in a Late Pleistocene–Holocene loess–paleosol sequence in central Argentina
Environmental Earth Sciences ( IF 2.8 ) Pub Date : 2021-01-06 , DOI: 10.1007/s12665-020-09324-5
Sabrina Rouzaut , Verena Agustina Campodonico , Andrea Inés Pasquini

A Late Pleistocene–Holocene loess–paleosol sequence in central Argentina was studied to obtain a weathering insight and to probe geochemical tools as paleoclimatic proxies. Three paleosols and a buried soil interlayered with loess mantles compose Corralito I sequence (32°00′7″ S, 64°11′08″ W, 469 m a.s.l). Several weathering indices (CIA, CIA-K, and LWI) and elemental ratios (∑Bases/Al2O3, Rb/Sr, CaO/TiO2, Na2O/TiO2) were calculated. An incipient weathering degree throughout the sequence was detected, denoting that the parent material (i.e., loess mantles) has not been substantially modified by pedogenesis. Although a statistically significant correlation between magnetic susceptibility and several weathering indices was identified, the weathering intensity was not strong enough to produce a decrease in the magnetic signal of the paleosols, which is, in part, inherited from the detrital fraction. Paleoprecipitation indices, calculated using geochemical data, suggest slightly wetter conditions during paleosol formation when compared to loess. Paleosols were formed during humid conditions (paleosols II and II during MIS 5e, and paleosol I during MIS 3) with sedimentation pause and soil development, whereas loess layers were deposited during more arid conditions.



中文翻译:

阿根廷中部晚更新世-全新世黄土-古土壤序列的风化和古降水指数

研究了阿根廷中部的晚更新世-全新世黄土-古土壤序列,以获取风化洞察力并探查作为古气候代理的地球化学工具。三个古土壤和一个由黄土幔夹层的埋藏土壤组成了Corralito I序列(32°00′7″ S,64°11′08″ W,469m asl)。几种风化指数(CIA,CIA-K和LWI)和元素比(∑Bases / Al 2 O 3, Rb / Sr,CaO / TiO 2,Na 2 O / TiO 2)进行了计算。在整个序列中都检测到初期的风化程度,表明母体材料(即黄土幔)没有被成岩作用实质性地改变。尽管确定了磁化率和几个耐候指数之间的统计学显着相关性,但耐候强度不足以使古土壤的磁信号降低,而这种减弱部分地源自碎屑组分。与黄土相比,使用地球化学数据计算得出的古降水指数表明古土壤形成过程中的条件略湿。古土壤是在潮湿的条件下形成的(MIS 5e中的古土壤II和II,MIS 3中的古土壤I),并伴有沉积暂停和土壤发育,

更新日期:2021-01-06
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