Zonal Stratigraphy of Neogene Deposits of the Eastern Part of the Atlantic Ocean by Means of Planktonic Foraminifers, Leg 41, Deep Sea Drilling Project
Zonal Stratigraphy of Neogene Deposits of the Eastern Part of the Atlantic Ocean by Means of Planktonic Foraminifers, Leg 41, Deep Sea Drilling Project
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利用浮游有孔虫对大西洋东部新近纪矿床进行地带性地层研究，深海钻探项目第 41 段
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发表时间：
1978
期刊：
影响因子：
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通讯作者：
U. Plfaumann
中科院分区：
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作者：
V. Krasheninnikov;U. Plfaumann
在第41航次期间，从非洲西北部海域的五个地点回收了新近纪沉积物。在塞拉利昂海隆（366号站点），新近纪沉积物由230米厚的纳米软泥、纳米白垩和钙质粘土组成，整合在渐新世晚期沉积物上。带的一般连续性以两个间断出现。下部间隙对应于下/中中新世边界周围的间隔（Praeorbulina glomerosa和Orbulina suturalis-Globorotalia peripheroronda带缺失），上部间隙与中/上中新世边界周围的间隔一致（Sphaeroidinellopsis subdehiscens-Globigerina druryi、Globigerina nepenthesGloborotalia siakensis和Globorotalia continuosa带缺失）。在佛得角盆地（367号站点），深水新近纪浊积岩（约200-250 m厚）中含有再沉积和分选的白垩纪、始新世、渐新世和新近纪物种的贫乏动物群。在佛得角海隆（368号站点），新近纪剖面开始于稍含钙质和非钙质的粘土，含中新世早期的弱透水性有孔虫。后来这一地区被抬升，粘土质沉积物在向上部分被更多的浅水粘土质纳米和纳米有孔虫软泥、泥灰岩和纯钙质软泥所取代。在中新世中期，浮游有孔虫仍然没有多样性，但自Globigerina nepenthes-Globorotalia siakensis带以来，几乎所有的新近纪带都已被追踪。新近纪沉积物的最小厚度约为230米。在西属撒哈拉大陆坡（369号站点）上，新近纪（164 m厚）的单一钙质远洋沉积物均匀地覆盖在渐新世晚期之上，或者有一个小的时间间隔。从Globigerinoides primordisGloborotalia kugleriZone到Globorotalia fohsi fohsi Zone之间的一组带已经被揭示出来，其中一个间隙对应于Globigerinitastainforthi和Globigerinatella insueta-Globigerinoides trilobus带。在此之上，是由钻井过程中沉积物的再沉积或混合造成的具有异质微型动物群的沉积物。该剖面以中新世晚期和上新世早期的沉积物结束，具有丰富的浮游有孔虫。后者不整合地被第四纪软泥覆盖。在摩洛哥盆地（站点370），深水泥灰岩和下中新统的钙质粘土中含有贫共生有孔虫组合。中中新世和上中新世以浊积岩（微软泥、粘土、粉砂岩和砂的交替）为代表，具有异质的微型动物群。新近系总厚度达200米。总的来说，所研究的区域的新近纪有孔虫微型动物群包括在热带-亚热带内发育的大多数物种。中新世和上新世有孔虫带的整个演替都发生了。唯一的例外是中中新世的Sphaeroidinellopsis subdehiscens-Globigerina druryi带。物种的分布在三个表格中。本文对47种有孔虫及其亚种进行了评述（地层范围、形态特征和壳壁超微结构）。
During Leg 41 Neogene sediments were recovered from five sites off northwest Africa. On the Sierra Leone Rise (Site 366), Neogene sediments consist of nanno oozes, nanno chalk, and calcareous clays 230 meters thick, resting conformably on the late Oligocene sediments. The common succession of zones occurs with two hiatuses. The lower gap corresponds to an interval around the lower/middle Miocene boundary (the Praeorbulina glomerosa and Orbulina suturalis-Globorotalia peripheroronda zones are absent) and the upper gap coincides with an interval around the middle/upper Miocene boundary (the Sphaeroidinellopsis subdehiscens-Globigerina druryi, Globigerina nepenthesGloborotalia siakensis and Globorotalia continuosa zones are missing). In the Cape Verde Basin (Site 367) deep-water Neogene turbidites (about 200-250 m thick) contain poor fauna of redeposited and sorted Cretaceous, Eocene, Oligocene, and Neogene species. On the Cape Verde Rise (Site 368) the Neogene section starts with slightly calcareous and noncalcareous clays with poor planktonic foraminifers of the lower Miocene. Later on this area was uplifted and clayey sediments have been replaced upsection in order by more shallow-water clayey nanno and nannoforaminifer oozes and marls and pure calcareous oozes. In the middle Miocene, planktonic foraminifers are still not diverse, but since the level of the Globigerina nepenthes-Globorotalia siakensis Zone, almost all Neogene zones have been traced. The minimum thickness of the Neogene sediments is about 230 meters. On the continental slope off Spanish Sahara (Site 369) monotonous calcareous pelagic sediments of Neogene age (164 m thick) overlie the late Oligocene comformably, or with a small time gap. A set of zones beginning from the Globigerinoides primordisGloborotalia kugleri Zone up to the Globorotalia fohsi fohsi Zone has been revealed with a gap corresponding to the Globigerinita stainforthi and the Globigerinatella insueta-Globigerinoides trilobus zones. Above that follow sediments with heterogeneous microfauna which result from redeposition or mixing of sediments during drilling. The section ends with sediments of the late Miocene and lower Pliocene with abundant planktonic foraminifers. The latter are unconformably overlain by the Quaternary ooze. In the Morocco basin (Site 370) deep-water marls and calcareous clays of the lower Miocene contain poor assemblages of planktonic foraminifers. The middle and upper Miocene are represented by turbidites (alternation of nanno oozes, clays, siltstones, and sands) with heterogeneous microfauna. Total thickness of Neogene is up to 200 meters. In general the Neogene foraminifer microfauna of the area studied includes the majority of species which developed within the tropical-subtropical belt. The entire succession of the Miocene and Pliocene foraminifer zones occurs. The only exclusion is the Sphaeroidinellopsis subdehiscens-Globigerina druryi Zone of the middle Miocene. The distribution of species is shown on three tables. Comments are given for 47 species and subspecies of foraminifers (stratigraphic ranges, peculiarities of morphology, and ultrastructure of the shell wall).