Marine Micropaleontology最新文献

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Calcareous Nannofossil variability controlled by Milankovitch and sub-Milankovitch periodicity in the Monte San Nicola section (Gelasian GSSP / MIS 100–104) 受米兰科维奇和亚米兰科维奇周期性控制的蒙特圣尼古拉剖面(格拉西GSSP / MIS 100-104)钙质化石的可变性
IF 1.5 4区 地球科学
Marine Micropaleontology Pub Date : 2024-09-01 DOI: 10.1016/j.marmicro.2024.102397
{"title":"Calcareous Nannofossil variability controlled by Milankovitch and sub-Milankovitch periodicity in the Monte San Nicola section (Gelasian GSSP / MIS 100–104)","authors":"","doi":"10.1016/j.marmicro.2024.102397","DOIUrl":"10.1016/j.marmicro.2024.102397","url":null,"abstract":"<div><p>The Quaternary marks the beginning of the ice ages, with the establishment of a stable Northern Hemisphere ice sheet. The Monte San Nicola section, southern Sicily (Italy) is the Global Boundary Stratotype Section and Point of the Gelasian Stage of the Lower Quaternary Subseries and is attracting new attention for providing valuable information on paleoclimate evolution.</p><p>Here we present a paleoenvironmental reconstruction based on new data from calcareous nannoplankton, the phytoplankton organisms that are sensitive to sea surface changes and water column dynamics. We adopt statistical and signal analysis to support our paleoenvironmental model. The most evident paleoenvironmental signal throughout the investigated interval is the contrast between the abundance patterns of placoliths and <em>Florisphaera profunda</em>, the former pointing to surface productivity (water column mixing, shallow nutricline), the latter to the establishment of a deep nutricline. The observed nutricline depth shift occurred with a regular precessional pace, following Northern Hemisphere summer insolation and, likely, North African monsoon activity. A significant periodicity of 8 kyr, in tune with late Quaternary Heinrich events, is also observed in nannoplankton taxa, supporting previous findings on the existence of suborbital climatic variability even at the Pliocene-Pleistocene transition.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377839824000677/pdfft?md5=e9e62edcb14e48537ccc5dbd5e8458e6&pid=1-s2.0-S0377839824000677-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142274669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Benthic foraminifera biomass on the continental slope and São Paulo plateau of Santos Basin (SE Brazil): Comparison of different estimation methods 桑托斯盆地(巴西东南部)大陆坡和圣保罗高原的底栖有孔虫生物量:不同估算方法的比较
IF 1.5 4区 地球科学
Marine Micropaleontology Pub Date : 2024-09-01 DOI: 10.1016/j.marmicro.2024.102396
{"title":"Benthic foraminifera biomass on the continental slope and São Paulo plateau of Santos Basin (SE Brazil): Comparison of different estimation methods","authors":"","doi":"10.1016/j.marmicro.2024.102396","DOIUrl":"10.1016/j.marmicro.2024.102396","url":null,"abstract":"<div><p>The biomass of benthic foraminifera stands out in marine environments compared to other meiofaunal organisms. Estimating the biomass of these organisms is a valuable biotic descriptor for understanding the carbon cycle and the flow of particulate organic matter. This study estimates the biomass of benthic foraminifera on the slope and plateau of the Santos Basin (SE Brazil) using the biovolume and cytoplasmic occupancy methodology. This work applies a non-destructive biovolume method of estimating biomass by the direct visualization of cytoplasmic occupancy (DV) compared with pre-established (in the literature) percentages of cytoplasmic occupation of the test volume: an average of 32 % (GE) and 35 % (AL). Although there was no statistically significant difference (<em>p</em> &lt; 0.05) between DV and cytoplasmic percentages, it is recognized that the calculation of GE and AL can bias the results. We, therefore, emphasize the need to assess biomass according to species composition and ultrastructural variability. The species with the biggest individuals (&gt;250 μm) contributed most to biomass in the Santos Basin and are considered k-strategists. In contrast, the species with smaller specimens (250–63 μm) are considered r-strategists, contributing more to the density in the study area. This study highlights the discrepancy between the abundant species biomass results by measuring all specimens and the extrapolation of the population for less sample effort, probably due to biological (e.g. intra/inter species variations) and environmental (e.g. availability of food and oxygen) factors. Based on the ecology of the species, the biomass estimates seem to reveal a relationship with the quantity and quality of organic matter, which will be investigated in the future. Future studies should consider the internal structures and address potential errors resulting from cytoplasm dehydration when staining and drying are performed.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142274670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Integrated record of the Late Lutetian Thermal Maximum at IODP site U1508, Tasman Sea: The deep-sea response 塔斯曼海 U1508 号 IODP 遗址的晚吕特世热极盛期综合记录:深海反应
IF 1.5 4区 地球科学
Marine Micropaleontology Pub Date : 2024-08-01 DOI: 10.1016/j.marmicro.2024.102390
{"title":"Integrated record of the Late Lutetian Thermal Maximum at IODP site U1508, Tasman Sea: The deep-sea response","authors":"","doi":"10.1016/j.marmicro.2024.102390","DOIUrl":"10.1016/j.marmicro.2024.102390","url":null,"abstract":"<div><p>The Late Lutetian Thermal Maximum (LLTM) was a transient and brief global warming event recorded in the middle Eocene, at 41.52 Ma. The biotic response to the LLTM has been documented at only a few marine sites so far. Here, we present the first record of deep-sea benthic foraminiferal assemblage changes during the LLTM in the southwest Pacific at International Ocean Discovery Program Hole U1508C (1609 m water depth) in the Tasman Sea. The LLTM coincides with a negative excursion in bulk sediment δ<sup>13</sup>C (0.47‰) and benthic foraminifera δ<sup>13</sup>C (0.36‰), with changes in the relative abundance of benthic foraminiferal species and in the deep-water organic geochemistry. The decrease in diversity of the assemblages indicates environmental stress during the event, potentially linked to oxygen deficiency, as evidenced by the occurrence of dysoxic taxa (e.g. <em>Lenticulina</em> spp., <em>Turrillina brevispira)</em>. Although calcareous taxa dominate, the presence of corrosion-resistant species and poorly preserved foraminiferal tests suggest slightly CaCO<sub>3</sub>-corrosive bottom waters, but no dissolution was evident. We suggest the shallowing of the thermocline and enhanced water column stratification at this site during the LLTM.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377839824000604/pdfft?md5=c97ff157181eed26d3abc24cece62484&pid=1-s2.0-S0377839824000604-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142044859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
High resolution 3D images of sediment cores as powerful tool for exploring foraminiferal microhabitats 沉积岩芯的高分辨率三维图像是探索有孔虫微生境的有力工具
IF 1.5 4区 地球科学
Marine Micropaleontology Pub Date : 2024-08-01 DOI: 10.1016/j.marmicro.2024.102394
{"title":"High resolution 3D images of sediment cores as powerful tool for exploring foraminiferal microhabitats","authors":"","doi":"10.1016/j.marmicro.2024.102394","DOIUrl":"10.1016/j.marmicro.2024.102394","url":null,"abstract":"<div><p>Benthic foraminifera are marine protists largely used as bioindicators and proxies of paleo- environments. Epifaunal species are supposed to live at or above the sediment surface and are therefore used as proxies for bottom water conditions, while infaunal inhabit the sediment column, thus tracing porewater chemistry. Traditional analytical methods based on core slicing, however, have a low resolution that does not allow to precisely characterise the preferential microhabitat(s) of indicator species.</p><p>In this study we performed microtomographic analyses on an experimental sediment core, to observe the life-position of living foraminifera of two surface-dwelling species <em>Ammonia confertitesta</em> and <em>Haynesina germanica</em>, reported both as epifaunal or shallow infaunal. The images we obtained offered for the first time the possibility to observe each individual in 3D space with a numerical resolution of 13 μm/voxel.</p><p>The results revealed that the two species are never located above or at the sediment surface and have their preferential microhabitats in a sub-superficial sediment layer constrained in the 0–500 μm interval below the surface. Rapid decrease of abundances below this layer suggests that their microhabitat could be even more specific than previously thought.</p><p>μCT-scan of sediment cores is also a valuable tool to obtain high-resolution information about foraminiferal ecology. The described method is useful to assess the effective microhabitat of all foraminiferal species that are usually used as proxies for paleorecords, to ensure that the information we can obtain from them is attributable to bottom water or to porewater conditions at a specific sediment depth.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377839824000641/pdfft?md5=827d2d5b8568a4649849315add7d5747&pid=1-s2.0-S0377839824000641-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A new fusulinid species from the early Permian of northwestern Peninsular Malaysia: Evidence of the Artinskian warming event in the eastern Peri-Gondwanan Sibumasu Block 马来西亚半岛西北部二叠纪早期的一个新的燧石物种:近贡嘎山锡布马苏区块东部阿尔廷斯基变暖事件的证据
IF 1.5 4区 地球科学
Marine Micropaleontology Pub Date : 2024-08-01 DOI: 10.1016/j.marmicro.2024.102391
{"title":"A new fusulinid species from the early Permian of northwestern Peninsular Malaysia: Evidence of the Artinskian warming event in the eastern Peri-Gondwanan Sibumasu Block","authors":"","doi":"10.1016/j.marmicro.2024.102391","DOIUrl":"10.1016/j.marmicro.2024.102391","url":null,"abstract":"<div><p>A new species of <em>Crenulosepta</em>, i.e., <em>Crenulosepta perlisensis</em> Vachard and Fassihi sp. nov., is described from a Cisuralian (Lower Permian) sandy limestones and calcareous sandstones in the Kubang Pasu Formation in northwestern Peninsular Malaysia, which forms part of the Peri-Gondwanan Sibumasu Block. Previous Malaysian authors reported the occurrence of <em>Monodiexodina shiptoni</em> and <em>Monodiexodina sutschanica</em> from the same area. The findings of this study provide a better overview of the Cisuralian fusulinid fauna found in this region. The presence of <em>Crenulosepta</em> confirms that the age of the uppermost part of the Kubang Pasu Formation is Artinskian, rather than extending into the Kungurian as previously recognized. The uppermost part of the Kubang Pasu Formation with its impoverished genus and species diversity is located just above the cold water brachiopods and diamictite beds. It indicates that during the Asselian (earliest Cisuralian), the northwestern Peninsular Malaysia was still part of the Gondwana continental shelf. During the late Early Permian, northwestern Peninsular Malaysia, as part of the eastern Cimmerian Continent, was located in a low latitude subtropical region of the paleo-equatorial tropical Tethyan Realm. The microfacies analysis of the Kubang Pasu Formation suggests a very high-energy, warm shallow marine environment of the inner ramp (e.g., sand shoals and banks).</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Unravelling changes in the productivity regime during the Late Miocene-Early Pliocene Biogenic Bloom: Insights from the western equatorial Pacific (IODP Site U1488) 揭示中新世晚期-上新世早期生物盛期生产力机制的变化:来自西赤道太平洋的启示(IODP U1488站点)
IF 1.5 4区 地球科学
Marine Micropaleontology Pub Date : 2024-08-01 DOI: 10.1016/j.marmicro.2024.102395
{"title":"Unravelling changes in the productivity regime during the Late Miocene-Early Pliocene Biogenic Bloom: Insights from the western equatorial Pacific (IODP Site U1488)","authors":"","doi":"10.1016/j.marmicro.2024.102395","DOIUrl":"10.1016/j.marmicro.2024.102395","url":null,"abstract":"<div><p>The Late Miocene-Early Pliocene Biogenic Bloom (9.0–3.5 Ma) is a widespread paleoceanographic phenomenon marked by increased marine biological productivity and by high accumulations of biological components documented at multiple open ocean sites in the Indian, Pacific, and Atlantic oceans. We investigate the expression of the Biogenic Bloom at International Ocean Discovery Program (IODP) Site U1488 in the western equatorial Pacific Ocean. We generated an improved age model based on calcareous nannofossil biostratigraphy and a quantitative benthic foraminiferal record across the Late Miocene to the Early Pliocene. Increased carbonate mass accumulation rates suggest the Biogenic Bloom occurs between 8.1 and 4.0 Ma at Site U1488. We described four intervals with paleoenvironmental significance: Interval 1 (8.1–6.2 Ma), Interval 2 (6.2–5.5 Ma), Interval 3 (5.5–4.5 Ma), and Interval 4 (4.5–3.1 Ma), the Biogenic Bloom spans across Interval 1 and 3. Intervals 1, 3, and 4 are marked by high abundance of phytodetritus exploiting taxa, related to phases of El Niño-like conditions. The highest abundance of these species during Interval 1 has been related to a phase of higher seasonality. In contrast, intervals 3 and 4 show reduced seasonality and a steadier input of food to the seafloor, associated with increased dust supply through wind transport and/or increased continental weathering during the Pliocene. Interval 2 stands out as the sole interval encompassing La Niña-like conditions, marked by a shift in the nutrient composition reaching the seafloor, from labile phytodetritus to refractory organic matter, and possibly a decrease in seasonality.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377839824000653/pdfft?md5=b7c95e136f64e79cacef479e25f89677&pid=1-s2.0-S0377839824000653-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142122200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Multiple short-lived marine incursions into the interior of Southwest Gondwana during the Aptian 古元古代期间冈瓦纳西南大陆内部多次短暂的海洋入侵
IF 1.5 4区 地球科学
Marine Micropaleontology Pub Date : 2024-08-01 DOI: 10.1016/j.marmicro.2024.102389
{"title":"Multiple short-lived marine incursions into the interior of Southwest Gondwana during the Aptian","authors":"","doi":"10.1016/j.marmicro.2024.102389","DOIUrl":"10.1016/j.marmicro.2024.102389","url":null,"abstract":"<div><p>The Lower Cretaceous sediments of the Sanfranciscana Basin, southeast Brazil, are considered to have been deposited under a Gondwanan continental context. However, different authors have occasionally observed marine elements in these same deposits. This study analyzes samples from five sections of the Sanfranciscana Basin, Quiricó and Três Barras formations, to characterize the paleoenvironment around these marine incursions. We recovered continental (non-marine ostracods and palynomorphs) and marine microfossils (e.g., foraminifera, radiolarians, and ascidian spicules). The alternance of quartz-rich biogenic chert and claystone might be indicative of the occurrence of radiolarites in the studied sessions. The presence of the radiolarian genus <em>Turbocapsula</em> sp., the radiolarian species <em>H</em>o<em>locryptocapsa fallax</em>, and the palynomorph <em>Tucanopollis crisopolensis</em> enabled us to date the interval as early Aptian. Based on the lithologies and microfossils recovered, we interpreted the studied interval as a continental setting that was episodically subjected to marine incursions. We propose three successive paleoenvironmental scenarios: (1) an initial lacustrine depositional setting with a non-marine biota; (2) a second stage, characterized by the presence of episodic marine influence in the sedimentary succession (as evidenced by radiolarians, foraminifera and ascidians), and (3) the return to continental settings dominated by aeolian dune fields. These environmental scenarios characterize the initial development of the Central Segment of the South Atlantic Ocean.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141961846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Assessing temporal transition between microgranular and hyaline tests of calcareous microplankton during the Late Jurassic 评估晚侏罗世钙质微浮游生物的微颗粒和透明试验之间的时间过渡
IF 1.5 4区 地球科学
Marine Micropaleontology Pub Date : 2024-06-01 DOI: 10.1016/j.marmicro.2024.102379
Diana Ölveczká , Adam Tomašových , Daniela Reháková , Ján Schlögl , Jozef Michalík
{"title":"Assessing temporal transition between microgranular and hyaline tests of calcareous microplankton during the Late Jurassic","authors":"Diana Ölveczká ,&nbsp;Adam Tomašových ,&nbsp;Daniela Reháková ,&nbsp;Ján Schlögl ,&nbsp;Jozef Michalík","doi":"10.1016/j.marmicro.2024.102379","DOIUrl":"https://doi.org/10.1016/j.marmicro.2024.102379","url":null,"abstract":"<div><p>Calcareous microplankton increased in abundance during the latest Jurassic, coinciding with the increase in abundance of calcareous nannofossils and with the onset of deposition of pelagic calcareous oozes. However, the timing and causes of the shift from microgranular tests of the earliest microplankton (chitinoidellids) to hyaline tests of calpionellids are obscured because the ultrastructure of two-layered praecalpionellids that occur during the Tithonian is poorly documented. Here, we investigate the ultrastructure of chitinoidellids and praecalpionellids from Upper Tithonian deposits in the Western Carpathians. We show that (1) the chitinoidellid microgranular layer is formed by elongated, euhedral, densely-packed, nanometric needles rather than by fragments of calcareous nannofossils, (2) two-layered chitinoidellids (<em>Semichitinoidella</em>) are formed by an internal microgranular layer (identical to that of <em>Chitinoidella</em>) and by an external hyaline prismatic layer, and (3) two-layered <em>Praetintinnopsella</em> exhibits an internal hyaline layer (with densely-packed, equant microcrystals) and an external layer formed by a dark organic rim. The external layer in <em>Praetintinnopsella</em> thus does not have any relation to the microgranular layer in chitinoidellids and the external hyaline layer of <em>Semichitinoidella</em> is not equivalent in structure to the hyaline layer of <em>Praetintinnopsella</em>. As both single-layer and two-layered chitinoidellids appear prior to the first appearance of <em>Praetintinnopsella</em> but still co-occur with this genus in the lowermost Upper Tithonian deposits, the origin of two-layered <em>Praetintinnopsella</em> either reflects a major transformation in biomineralization towards larger and more packed crystals during their earlier divergence from the chitinoidellid lineage or an origination of two-layered tests with a hyaline layer from an independent non-chitinoidellid ancestor.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141543508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Evolutionary change of crystallographic orientation and coccolith morphology: Neogene-Quaternary Umbilicosphaera (Prymnesiophyceae) lineage 晶体取向和茧石形态的进化变化:新近纪-第四纪脐带藻(Prymnesiophyceae)世系
IF 1.9 4区 地球科学
Marine Micropaleontology Pub Date : 2024-06-01 DOI: 10.1016/j.marmicro.2024.102370
Masayuki Utsunomiya , Toshihiro Kogure
{"title":"Evolutionary change of crystallographic orientation and coccolith morphology: Neogene-Quaternary Umbilicosphaera (Prymnesiophyceae) lineage","authors":"Masayuki Utsunomiya ,&nbsp;Toshihiro Kogure","doi":"10.1016/j.marmicro.2024.102370","DOIUrl":"https://doi.org/10.1016/j.marmicro.2024.102370","url":null,"abstract":"<div><p>The crystallographic orientation and its relationship to the morphology of coccoliths were investigated for the Neogene-Quaternary calcareous nannoplankton <em>Umbilicosphaera</em> lineage using scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD). The <strong>c</strong>-axis of the calcite forming the distal shield elements was inclined upward at 66–68° (<em>U. sibogae</em>), 65–68° (<em>U. foliosa</em>), 57–58° (<em>U. rotula</em>), and 55–57° (<em>U. patera</em>) from the coccolith plane. Accordingly, the outward dip angle of one of the {<span><math><mn>10</mn><mover><mn>1</mn><mo>¯</mo></mover><mn>4</mn></math></span>} faces forming the surface of the distal shield of <em>U. patera</em> coccolith was shallower than those of <em>U. sibogae</em> and <em>U. foliosa</em>, explaining the nearly flat distal shield and the steep inner slope, formed by another equivalent {<span><math><mn>10</mn><mover><mn>1</mn><mo>¯</mo></mover><mn>4</mn></math></span>} face, around the central opening of <em>U. patera</em>. Our results showed that the evolution from <em>U. rotula</em> to <em>U. patera</em> during the Late Miocene was not accompanied by a change in crystallographic orientation. In contrast, the evolution from <em>U. patera</em> to <em>U. sibogae</em> and <em>U. foliosa</em> during the Pliocene was accompanied by a rotation of the orientation. The crystallographic orientation of calcite nuclei on the baseplate with a combination of other factors would have resulted in species-specific differences in shield shape and suture lines within the same phylogeny, consequently producing morphological diversity in the coccolith throughout geological time.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141242143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Unraveling ecological signals related to the MECO onset through planktic and benthic foraminiferal records along a mixed carbonate-siliciclastic shallow-water succession 通过沿碳酸盐-硅质岩混合浅水演替的浮游和底栖有孔虫记录,揭示与 MECO 开始有关的生态信号
IF 1.5 4区 地球科学
Marine Micropaleontology Pub Date : 2024-06-01 DOI: 10.1016/j.marmicro.2024.102388
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