气候变化领域集成服务门户(CCPortal): Dynamic surface-water alterations during sapropel S1 preserved in high-resolution shallow-water sediments of Taranto Gulf; central Mediterranean

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DOI	10.1016/j.palaeo.2019.109340
	Dynamic surface-water alterations during sapropel S1 preserved in high-resolution shallow-water sediments of Taranto Gulf; central Mediterranean
	Maiorano P.; Marino M.; De Lange G.J.
发表日期	2019
ISSN	0031-0182
卷号	534
英文摘要	The high sedimentation rate and shallow-water depositional depth of the sediments at site DP 30 in the Gulf of Taranto (central Mediterranean) provide unique biogenic signals that are usually not preserved in deeper records. This permits the reconstruction of long and short-term surface water modifications across the sapropel S1 period (10–6.5 ka), including calcareous nannofossil data at centennial-scale resolution. The peculiar patterns of key taxa allowed the recognition of distinct long to short-term surface water changes that provide valuable evidence on climate conditions leading to sapropel deposition. As a long-term pattern, S1 is marked by a distinct increase of Helicosphaera carteri, thought to reflect increased detrital input/land-derived nutrients in the surface water, related to a higher influence of the Western Adriatic Current. A concomitant pattern of increased black organic particles in the sediments supports a connection between organic matter preservation at the seafloor and nutrient availability in the surface water. Decreased salinity in the surface water, testified by an increase of Braurudosphaera bigelowii, develops from 9.2 up to 6.5 ka. At higher frequencies, additional changes occurred in surface-subsurface waters during the formation of S1 at shallow depths. Starting from 11 ka, the relative abundance pattern of Florisphaera profunda indicates a gradual nutrient enrichment in the subsurface waters and the development of a deep chlorophyll maximum (DCM), which becomes well established at the onset of sapropel S1, between 10 and 9 ka. A further change in the plankton ecosystem occurs between 9 and 8.2 ka, when reduced coccolithophore production is concomitant with diatom occurrence and enhanced Br/Ti level, implying a productivity increase. From 8 to 6.5 ka, coccolithophore productivity is re-established in relation to a reduction both in surface-water stratification and turbidity/nutrient availability, characterizing the final phase of sapropel formation. The turbidity in the surface waters was briefly reduced at 8.2 and 7.3 ka, when also oxygen conditions at the seafloor improved. A centennial variability in turbidity/low light conditions in surface waters is evident across S1 and is illustrated by the abundance patterns of H. carteri and Gladiolithus flabellatus. The occurrence of ascidian spicules also represents a distinct biotic signal across the S1 layer, indicating an increase of shallow-water biogenic carbonate or an aragonitic near-coastal source. Surface-water modifications at longer and shorter time scales, accompanying the deposition of sapropel S1 in the Gulf of Taranto, occurred nearly simultaneously and with a magnitude that is comparable to changes observed in S1 deposits in the central and eastern Mediterranean basin and slope settings. © 2019 Elsevier B.V.
英文关键词	Biogenic content preservation; Calcareous nannofossils; Core DP 30; Primary productivity
语种	英语
scopus关键词	biogenic deposit; climate conditions; coastal sediment; coccolith; depositional environment; diatom; historical record; nanofossil; organic matter; preservation; primary production; reconstruction; relative abundance; sedimentation; shallow water; surface water; Adriatic Sea; Gulf of Taranto; Ionian Sea; Mediterranean Sea; Ascidia; Bacillariophyta; Helicosphaera carteri
来源期刊	Palaeogeography, Palaeoclimatology, Palaeoecology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/150786
作者单位	Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi di Bari Aldo Moro, Italy; Department of Earth Sciences-Geochemistry, Faculty Geosciences, Utrecht University, Netherlands
推荐引用方式 GB/T 7714	Maiorano P.,Marino M.,De Lange G.J.. Dynamic surface-water alterations during sapropel S1 preserved in high-resolution shallow-water sediments of Taranto Gulf; central Mediterranean[J],2019,534.
APA	Maiorano P.,Marino M.,&De Lange G.J..(2019).Dynamic surface-water alterations during sapropel S1 preserved in high-resolution shallow-water sediments of Taranto Gulf; central Mediterranean.Palaeogeography, Palaeoclimatology, Palaeoecology,534.
MLA	Maiorano P.,et al."Dynamic surface-water alterations during sapropel S1 preserved in high-resolution shallow-water sediments of Taranto Gulf; central Mediterranean".Palaeogeography, Palaeoclimatology, Palaeoecology 534(2019).