Evoluzione sedimentaria e paleoclimatologia tardo-quaternaria della scarpata continentale del Golfo di Policastro (Mar Tirreno meridionale)
Evoluzione sedimentaria e paleoclimatologia tardo-quaternaria della scarpata continentale del Golfo di Policastro (Mar Tirreno meridionale)
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沉积物和古气候学的进化史（Mar Tirreno meridionale）
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发表时间：
2002
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通讯作者：
C. Vecchione
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作者：
G. Buccheri;M. Bertoldo;M. Coppa;R. Munno;Micla Pennetta;G. Siani;A. Valente;C. Vecchione
对波利卡斯特罗湾斜坡（第勒尼安海）C45 钻芯进行的多学科研究旨在对该地区的生物地层学、古气候学、岩石年代学、沉积学和古生态学做出贡献。沉积序列为晚更新世-全新世，沉积时期为距今32-30ka。一些细分是根据沉积学分析来区分的。恢复的序列由粉质粘土和粘土质粉砂组成，具有四个富含火山碎屑成分的互层。沉积速率是可变的，1000年达到约20厘米的值。浊积岩主要发现于末次冰期沉积体（晚更新世）的下部，而在核心的中上部发现了频繁的白云岩，这对应于冰消期（晚冰期）和下一次冰期海侵（全新世）。火山碎屑层厚度为几厘米，与索马维苏威火山和Phlegrean Fields的大喷发事件有关，但属于Y3事件的火山喷发事件除外，该事件广泛分布于地中海地区，其源头仍然未知。本报告还对从 59 个岩心样本中回收的有孔虫和翼足类动物群落进行定量动物区系分析，以重建岩心位置水团的古气候条件。这表明在序列的中下部出现了翼足类的高产寡型组合，主要包括亚寒带物种Limacina revversa。还认识到一些亚极地过渡水域典型的浮游有孔虫类群，如 Globorotalia scitula、Neogloboquadrina pachyderma lx、Turborotalita quinqueloba。从 180 厘米到顶部，这些组合被其他温带和/或暖温带物种所取代，物种多样性较高，表明存在亚热带-热带水团（其中主要是翼足类的 Limacina infata 和浮游有孔虫的 Globigerinoides spp.）。根据冷水和暖水指标累积百分比的代数和推断浮游有孔虫和翼足类的古气候曲线。他们表明，该序列的基底和中部部分可以参考末次冰期（Wurm），并且该组合反映了明显的大西洋影响，而上部则显示了晚更新世-全新世典型的地中海西部和东部的特征物种。比较了推断的气候曲线：基本上它们非常一致，但有孔虫曲线中的气候脉动不太明显。最重要的测年事件有：末次盛冰期（大约 19-18 ka BP）、Bolling-Allerod 暖事件（13 -11 ka BP）、新仙女木冷温带事件（大约 11-10 ka BP），其顶部标志着上更新世-全新世过渡。这些关键事件的年龄与 1 4 C 测年一起用于计算岩心的沉积速率。古生态学结果表明，沉积物的时间演化、生产力和组合（主要是翼足类动物）的具体多样性受到气候和海平面变化以及在所考虑的时间跨度内影响第勒尼安海的火山事件的控制。
A multidisciplinary study of drill core C45 from the Gulf of Policastro slope (Tyrrhenian Sea) was aimed at contributing to the biostratigraphy, paleoclimatology, tephrochronology, sedimentology and paleo-ecology of the region. The sedimentary sequence, Late Pleistocene-Holocene in age, was deposited during the 32-30 ka before present. Some subdivisions have been distinguished on the basis of sedimentological analyses. The succession recovered consists of silty-clay and clayey-silt with four interbedded levels rich in pyroclastic components. The sedimentation rate is variable, reaching the value of about 20 cm for 1.000 years. Turbidites have been mainly recognized in the lower part of last glacial sedimentary body (Late Pleistocene), whereas frequent pelagites have been found in the middle and upper part of the core which correspond to a deglaciation phase (Late glacial) and to the next post glacial transgression (Holocene). The pyroclastic horizons, a few centimetres in thickness, are related to the great eruptive events of the Somma Vesuvius and Phlegrean Fields except for one which belongs to the event known as Y3, widespread in the Mediterranean region, whose source area is still unknown. The present report also deals with the quantitative faunal analyses of foraminiferal and pteropod assemblages recovered from 59 samples of core, in order to reconstruct the paleoclimatic conditions of water masses at the core location. This shows that in the lower and middle part of sequence high-productivity and oligotypic assemblages of Pteropods occur, mainly containing the subartic species Limacina retroversa. Also some taxa of planktonic foraminifers typical of subpolar-transitional waters as Globorotalia scitula, Neogloboquadrina pachyderma lx, Turborotalita quinqueloba were recognized. From 180 cm toward the top, these assemblages were replaced by others with temperate and/or warm-temperate species, with higher species diversity indicative of subtropical-tropical water masses (among which mainly Limacina inflata for the Pteropods and Globigerinoides spp. for planktonic Foraminifers). Paleoclimatic curves for the planktonic Foraminifers and Pteropods were inferred based on the algebraic sum of the cumulative percentages of cold and warm water indicators. They show that the basal and middle parts of the sequence can be referred to the last glaciation (Wurm) and that the assemblages reflect a clear Atlantic influence whereas the upper part shows characteristic species of western and eastern Mediterranean typical of Late Pleistocene-Holocene Epoch. The inferred climatic curves were compared: basically they are in good agreement but the climatic pulsations are less evident in the foraminifers curve. The most significant dated events are: the Last glacial maximum (about 19-18 ka BP), the Bolling-Allerod warm event (13 -11 ka BP), the Younger Dryas cold-temperate event (about 11-10 ka BP), whose top marks the Upper Pleistocene-Holocene transition. The ages of these key events together with 1 4 C dating were used to calculate the sedimentation rates of the core. The palaeoecological results indicate that the time-evolution of the sedimentation, the productivity and the specific diversity of the assemblages (mainly of the Pteropods) were controlled by climatic and eustatic changes, and by volcanic events affecting the Tyrrhenian Sea during the time span considered.