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Middle to late Miocene Caribbean dinoflagellate assemblages and palynofacies (DSDP Leg 15 Site 153)
Marine Micropaleontology ( IF 1.9 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.marmicro.2020.101898
Lilian M. Leandro , Alessandra Santos , Marcelo de A. Carvalho , Gerson Fauth

Abstract Changes in oceanic circulation and productivity patterns near Central America have been explained using numerous different tools, such as tectonics, geochemistry and micropaleontology. This paper aims to contribute to this discussion through the study of dinoflagellates and palynofacies in the drill core from DSDP Site 153. Based on foraminiferal data, the studied section is divided into the middle and upper Miocene, and our dinoflagellate events also support an age model of ~15 to 8 Ma. IndVal, ecological indexes, and the (P/G) dinoflagellate ratios were used to develop paleoenvironmental inferences. The indicator species are Operculodinium centrocarpum and Tectatodinium pellitum for the MM1 interval, Spiniferites spp. and Impagidinium strialatum for MM2, and Selenopemphix armageddonensis, Lejeunecysta spp. and L. tenella for UM3. Intervals MM1 and MM2 are characterized by a dominance of gonyaulacoids, and inner to outer neritic environments. The UM3 interval is interpreted as an outer neritic environment in the base/middle portion, and inner neritic in the uppermost part, with a shift from gonyaulacoid to peridinioid dominance, suggesting an increase in productivity. During the middle Miocene, productivity is low due to intermittent marine circulation restrictions in the Caribbean Sea, and there is a slight increase during the upper Miocene following reestablishment of the global oceanic circulation. This is directly connected to the occurrence of geotectonic and paleoceanographic events in the region during the Miocene, mainly by mass movements such as the Panama gateway and the opening of the Pedro Channel to the north, changing the surface conditions in the Caribbean Sea.

中文翻译:

中新世中晚期加勒比甲藻组合和孢粉相(DSDP Leg 15 Site 153)

摘要 中美洲附近海洋环流和生产力模式的变化已经使用多种不同的工具进行了解释,例如构造学、地球化学和微古生物学。本文旨在通过研究 DSDP Site 153 钻芯中的甲藻和孢粉相来促进这一讨论。根据有孔虫数据,研究部分分为中新世和中新世,我们的甲藻事件也支持年龄模型约 15 至 8 毫安。IndVal、生态指数和 (P/G) 鞭毛藻比率用于开发古环境推断。MM1 区间的指示物种是 Operculodinium centrocarpum 和 Tectatodinium pellitum,Spiniferites spp。和用于 MM2 的 Impagidinium strialatum,和 Selenopemphix armageddonensis,Lejeunecysta spp。和 L. tenella 为 UM3。区间 MM1 和 MM2 的特点是角状藻类占优势,以及从内到外的浅海环境。UM3 区间被解释为基部/中部的外部浅海环境和最上部的内部浅海环境,从 gonyaulacoid 到 peridinioid 优势转变,表明生产力增加。在中中新世,由于加勒比海间歇性的海洋环流限制,生产力低下,随着全球海洋环流的重建,在上中新世期间产量略有增加。这与中新世期间该地区发生的大地构造和古海洋事件直接相关,主要是由于巴拿马门户和佩德罗海峡向北开放等大规模运动,
更新日期:2020-09-01
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