The response of calcareous nannoplankton to sea surface variability at Ceara Rise during the early Pleistocene glacial-interglacial cycles

IF 1 4区地球科学 Q4 GEOSCIENCES, MULTIDISCIPLINARY

Italian Journal of Geosciences Pub Date : 2019-02-01 DOI:10.3301/IJG.2018.22

A. Incarbona, E. Stefano, P. Maiorano, M. Marino, N. Pelosi

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Abstract

The Ceara Rise lies just beyond the edge of the Amazon River Fan and sediments from this site may record the complex interplay of different climatic systems and processes, including past changes in southern America monsoon activity, Intertropical Convergence Zone setting, different Atlantic Meridional Overturning Circulation (AMOC) strength and phytoplankton blooming triggered by AmazonRiver plumes. Here we investigate early Pleistocene calcareous nannoplankton at Ceara Rise, between about 1150 and 850 kiloyears ago. Our investigation shows abrupt variations in water column dynamics across glacial/interglacial cycles or, even better, linked with different AMOC modes. Dominant placoliths indicate a shallow nutricline that alternate with dominant Florisphaera profunda, pointing to a deep nutricline, respectively during a vigorous flow and slowdown/shutdown of AMOC. The southward displacement of the ITCZ, higher zonal trade wind intensity, more intense and prolonged North Brazilian Current retroflection and the arrival of the nutrientdepleted Glacial North Atlantic Intermediate Water possibly explain thermocline deepening and increased water column stratification during cold phases, with an Antarctic deep water signature on the Ceara Rise seafloor.

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早更新世冰期-间冰期旋回期间，钙质纳米浮游生物对北冰洋海平面变化的响应

Ceara海隆位于亚马逊河扇边缘之外，该地点的沉积物可能记录了不同气候系统和过程的复杂相互作用，包括过去南美洲季风活动的变化、热带辐合带的设置、，不同的大西洋经向翻转环流（AMOC）强度和亚马逊河羽状物引发的浮游植物开花。在这里，我们调查了大约1150至850千年前Ceara隆起的早更新世钙质超微浮游生物。我们的研究表明，在冰川/间冰川周期中，水柱动力学的突然变化，或者更好的是，与不同的AMOC模式有关。优势平台表示浅营养层，与优势Florisphaera deprenda交替，分别在AMOC的剧烈流动和减速/关闭期间指向深营养层。ITCZ向南移动、更高的纬向信风强度、更强烈和更长时间的北巴西洋流反向反射以及营养耗尽的冰川北大西洋中间水的到来，可能解释了冷期温跃层加深和水柱分层增加的原因，Ceara海隆海底有南极深水特征。

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来源期刊

Italian Journal of Geosciences GEOSCIENCES, MULTIDISCIPLINARY-

CiteScore

2.90

自引率

11.10%

发文量

审稿时长

>12 weeks

期刊介绍： The Italian Journal of Geosciences (born from the merging of the Bollettino della Società Geologica Italiana and the Bollettino del Servizio Geologico d''Italia) provides an international outlet for the publication of high-quality original research contributions in the broad field of the geosciences. It publishes research papers, special short papers, review papers, discussion-and-replies for their rapid distribution to the international geosciences community. The journal is firstly intended to call attention to the Italian territory and the adjacent areas for the exceptional role they play in the understanding of geological processes, in the development of modern geology and the Earth sciences in general. The main focus of the journal is on the geology of Italy and the surrounding sedimentary basins and landmasses, and on their relationships with the Mediterranean geology and geodynamics. Nevertheless, manuscripts on process-oriented and regional studies concerning any other area of the World are also considered for publication. Papers on structural geology, stratigraphy, sedimentology, basin analysis, paleontology, ecosystems, paleoceanography, paleoclimatology, planetary sciences, geomorphology, volcanology, mineralogy, geochemistry, petrology, geophysics, geodynamics, hydrogeology, geohazards, marine and engineering geology, modelling of geological process, history of geology, the conservation of the geological heritage, and all related applied sciences are welcome.