Is the spring water responsible for the fossilization of faunal remains at Florisbad, South Africa?

It is has been suggested that faunal remains at Florisbad were fossilized in a spring context due to the mineralized spring water. However, the environment conducive to the precipitation of CaCO₃ and other authigenic minerals was formed largely through the salinization of the organic layers and clay, and the mineralization of the groundwater. Factors contributing to this favorable environment include: CaCO₃ saturation, pH, the decomposition of halophytes, Eh, rainfall, biomineralization, and aeolian deposition. With the exception of pH, none of the above factors feature in a spring context, with evidence suggesting that the spring water may historically never have carried sufficient minerals for fossilization, and that contact with the spring water may actually have resulted in the demineralization of previously fossilized material. In light of this evidence, it is concluded that the fossilization of faunal remains at Florisbad took place in a sedimentary organic matter and clay environment and could not have taken place in the spring vents where there is an undersaturation of Ca.     

Climatic and sea level controls on Late Quaternary eolian activity on the Agulhas Plain, South Africa

Located at the interface between the temperate westerly and sub-tropical climate systems, South Africa's winter rainfall zone (WRZ) is a key location in understanding Late Quaternary atmospheric circulation dynamics. Inactive eolian deposits in the WRZ, comprising pan-fringing lunette and coastal dunes, were investigated to establish their depositional ages and utility as paleoenvironmental indicators. The resulting optical luminescence chronology reveals episodic lunette accretion at 60,000-45,000 yr, 12,000-13,000 yr, 2800-2600 yr, 1200 yr, and <1000 yr, with coastal dune ages clustering at 4100-4700 yr.Episodes of lunette and coastal dune accretion on the Agulhas Plain are temporally distinct, reflecting differing fundamental controls on their activity. Comparisons to previously published data also reveal that the lunettes differ in age from more ancient coastal eolianites. Lunette deposition is asynchronous between locations, reflecting the topographic and hydrological setting of the individual pans. In near-coastal settings, with limited surface recharge, lunette accretion appears to be at least partially controlled by sea level induced changes in groundwater levels. Those pans with more significant surface recharge (particularly from fluvial systems) may produce less ambiguous paleoenvironmental records, with pan status more strongly reflecting regional hydrological conditions. Lunette orientation is indicative of strong westerly winds during both the Pleistocene and Holocene. Lunette accretion would have been promoted by reduced on-shore moisture transport during the summer months, enhancing rainfall seasonality. Such conditions would have been promoted by increased continentality as the Agulhas Bank was exposed during low sea level stands.     

New species of fossil oribatid mites (Acariformes,Oribatida), from the Lower Cretaceous amber of Spain

Mites are relatively common and diverse in fossiliferous ambers, but remain essentially unstudied. Here, we report on five new oribatid fossil species from Lower Cretaceous Spanish amber, including representatives of three superfamilies, and five families of the Oribatida. Hypovertex hispanicus sp. nov. and Tenuelamellarea estefaniae sp. nov. are described from amber pieces discovered in the San Just outcrop (Teruel Province). This is the first time fossil oribatid mites have been discovered in the El Soplao outcrop (Cantabria Province) and, here, we describe the following new species: Afronothrus ornosae sp. nov., Nothrus vazquezae sp. nov., and Platyliodes sellnicki sp. nov. The taxa are discussed in relation to other fossil lineages of Oribatida as well as in relation to their modern counterparts. Some of the inclusions were imaged using confocal laser scanning microscopy, demonstrating the potential of this technique for studying fossil mites in amber. A table, including all the known Mesozoic oribatid mites preserved in amber, is included.     

Astronomical time-scale for physical property records from Quaternary sediments of the northern North Atlantic

Deep sea sediment cores taken between 50° and 75°N in the North Atlantic, in water depths varying between 1340 and 3850 m, were examined to provide an astronomically calibrated late Quaternary time-scale based on physical property records. Magnetic susceptibility and gamma ray attenuation porosity evaluator (GRAPE) density changes of these cores revealed significant responses to orbital forcing in the eccentricity (100 kyr), obliquity (41 kyr) and precessional (23, 19 kyr) bands. At 75°N (Greenland Sea), a response to obliquity forcing was weak despite the fact that it should become more pronounced in sediments at high latitudes. Application of bandpass filtering at the obliquity period (41 kyr), however, showed that variance at this period did exist in the magnetic susceptibility record, but at a very low power. At 50°N stacked curves of magnetic susceptibility correlated strongly with the SPECMAP curve for the past 500 ka. Since about 65 ka, dropstone layers are recorded in both magnetic susceptibility and GRAPE data of Rockall Plateau sediments. Although Rockall Plateau sediments show peaks in physical properties that correlate with Heinrich events (H₁, H₂, H₄, H₅, H₆), such a relationship was not readily observed in Norwegian-Greenland Sea records. Heinrich events at Rockall Plateau sites indicate a northward flow of icebergs in the eastern North Atlantic. This flow pattern and the presence of Heinrich events during the past 65 ka raise the questions of whether similar events occurred before this time period, and to what kind of ice sheet dynamics and climatic-oceanographic conditions favoured major iceberg surges from the Laurentide ice sheet to the North Atlantic at 50°N.     

洞庭盆地澧县凹陷第四纪沉积特征与古地理演化

澧县凹陷内第四系厚度达200m左右,由早更新世-中更新世中期沉积和全新统组成。早更新世-中更新世中期沉积除顶部为粘土外,主体为砾石层,在凹陷中央夹粉砂、细砂和少量粘土。全新统分布于凹陷南部,为湖冲积粘土。早更新世澧县凹陷区断陷沉降,于河道和冲积扇环境下接受沉积;中更新世凹陷逐渐扩张,沉积范围扩展至凹陷外缘,凹陷主体部位自边缘向中央依次为冲积扇和扇前浅湖环境。中更新世中后期因盆地扩张,自凹陷中央至边缘地带均为静水湖泊环境。中更新世晚期至晚更新世,凹陷及周缘因构造抬升而遭受剥蚀而缺失沉积。全新世凹陷南部受澧水及区域湖面上升影响而发育湖冲积沉积。     

Infilling of the Younger Kathmandu–Banepa intermontane lake basin during the Late Quaternary (Lesser Himalaya,Nepal): a sedimentological study

The Kathmandu and Banepa Basins, Central Nepal, are located in a large syncline of the Lesser Himalayas. The Older Kathmandu Lake evolved during the Pliocene and early Pleistocene; the Younger Kathmandu Lake, which is the focus of this study, is infilled with late Quaternary sediments. Three formations, arranged in stratigraphical order, the Kalimati, Gokarna and Thoka Formations formed during the infilling stage of this lacustrine basin. Structural and textural sedimentological analyses, a chemical survey across the basin and mineralogical investigations of fine‐grained sediments form the basis of this palaeogeographical study. The basin under investigation was covered by a perennial freshwater lake before 30 000 yr BP. The lake was infilled with alluvial and fluvial sediments delivered mainly from the mountains north of the basin. A fairly low gradient was favourable for the formation of diatomaceous earths, carbonaceous mudstones and siltstones, which were laid down in the centre of the lake and in small ponds. Towards the basin edge, lacustrine sediments gave way to deltaic deposits spread across the delta plain. Crevasse splays and anastomosing rivers mainly delivered suspended load for the widespread siltstones and mudstones. The proximal parts of the alluvial–fluvial sedimentary wedge contain debris flows that interfinger with fine‐grained floodplain deposits. Three highstands of the water‐level (>30 000 yr BP, 28 000–19 000 yr BP, 11 000–4000 yr BP (?)) have been recognised in the sedimentary record of the younger Kathmandu Lake in the Late Quaternary. Second‐order water‐level fluctuations are assumed to be triggered by local processes (damming by tectonically induced landslides). First‐order water‐level fluctuations are the result of climatic changes. Copyright © 2003 John Wiley & Sons, Ltd.     

Late Quaternary fluvial activity in the dry valleys (mekgacha) of the Middle and Southern Kalahari,southern Africa

Kalahari dry ‘fossil’ valleys (mekgacha) have been little used in palaeoenvironmental reconstruction, partly because the origins and functions of the valleys are a subject of debate, and partly because they contain few datable sediments. In the Middle Kalahari the valleys are endoreic, and, following a decline in ground-water tables owing to human interference over the past 150 years, rarely contain water. Evidence from three sites suggests that the valleys contained standing water between 15000 and 12000 yr BP, and that the main Okwa-Mmone system flowed into palaeolake Makgadikgadi at 920 m a.s.l. during this period. The Southern Kalahari contains the exoreic Molopo network which is hydrologically more active, being prone to surface flows in response to extreme rainfall events. The spring—fed Kuruman valley has two terraces, the lower composed of a series of flood deposits of late Holocene age. The flood of February 1988 provides a useful analogue for the conditions under which these deposits were formed, and of the temporal regime of the Kuruman River. Comparison with adjacent sites suggests that evidence put forward to indicate cycles of climatic amelioration in the last 4000 yr may, in part, represents the effect of extreme precipitation events. Historical floods show a strong correlation to Southern Oscillation high-phase (cold event) episodes, suggesting possibilities for extension of the Southern Oscillation record through palaeoflood studies.     

南海北部陆坡ODP 1144站位第四纪硅藻及其古环境演变

中国南海北部陆坡ODP 1144站位硅藻植物群的研究，建立了西太平洋边缘海一个新的中更新世晚期以来的硅藻生物地层图式，根据硅藻化石中具有指示意义的硅藻种的分布和生态变化（暖水种和冷水种），划分了8个硅藻组合带，其硅藻组合带分别在不同的高低海面环境下形成的，根据ODP1144站位氧同位素（OIS）测定结果，8个硅藻组合带与OIS 1－8期相对应。1、3、5、7硅藻组合带相当于OIS1、3、5、7期，间冰期是以热带和亚热带硅藻占优势，其中冷期出现大量的沿岸硅藻为特征，反映高海平面温暖的气候条件；2、4、6、8硅藻组合带相当于OIS2、4、6、8期，冰期是以亚热带，热带和出现较多冷水硅藻为特征，反映低海平面较冷气候条件，硅藻丰度值的变化与冰期和间冰期有关，可以证实间冰期时期高的海平面和较低的生物生产力以及冰期时低的海平面和高的生物生产力，而生物生产力的变化又与沉积时期沿岸流或上升流的强弱及水团活动有密切关系，进而揭示该区古海洋环境的演化与季风强弱之间的内在关系。     

Late Quaternary core stratigraphy of the northern New South Wales continental shelf

On the southeast Australian continental margin, mixed siliciclastic and temperate carbonate sediments are presently forming along the narrow 20–35 km‐wide northern New South Wales shelf over an area of 4960 km². Here, year‐round, highly energetic waves rework inner and mid‐shelf clastic sediments by northward longshore currents or waning storm flows. The strong East Australian Current flows south, sweeping clastic and outer shelf biogenic sands and gravels. Quaternary siliciclastic inner shelf cores consist of fine to medium, lower shoreface sand and graded storm beds of fine to coarse sand. Physically abraded, disarticulated molluscs such as Donacidae and Glycymeridae form isolated gravel lags. Highstand inner shelf clastics accumulate at 0.53 m/10³ y in less than 50 m water depth. Clastic mid‐shelf cores contain well‐sorted, winnowed, medium shoreface sands, with a fine sand component. Fine sand and mud in this area is discharged mainly from New South Wales’ largest river, the Clarence. The seaward jutting of Byron Bay results in weakened East Australia Current flows through the mid‐shelf from Ballina to Yamba allowing the fine sediments to accumulate. Quaternary carbonate outer shelf cores have uniform and graded beds forming from the East Australian Current and are also influenced by less frequent storm energy. Modern clastic‐starved outer shelf hardgrounds are cemented by coralline algae and encrusting bryozoans. Clay‐sized particles are dominantly high‐Mg calcite with minor aragonite and smectite/kaolinite. Carbonate sands are rich in bryozoan fragments and sponge spicules. Distinctive (gravel‐sized) molluscs form isolated shells or shell lag deposits comprising Limopsidae and Pectinidae. The upper slope sediments are the only significant accumulation of surficial mud on the margin (18–36 wt%), filling the interstices of poorly sorted, biogenic gravels. Pectinid molluscs form a basal gravel lag. During highstand the outer shelf accumulates sediment at 0.40 m/10³ y, with the upper slope accumulating a lower 0.23 m/10³ y since transgression. Transgression produced a diachronous (14–10 ka) wave‐ravinement surface in all cores. Relict marine hardgrounds overlie the wave‐ravinement surface and are cemented by inorganic calcite from the shallow and warm East Australian Current. Transgressive estuarine deposits, oxygen isotope Stage 3–5 barriers or shallow bedrock underlie the wave‐ravinement surface on the inner and mid shelf. Northern New South Wales is an example of a low accommodation, wave‐ and oceanic current‐dominated margin that has produced mixed siliciclastic‐carbonate facies. Shelf ridge features that characterise many storm‐dominated margins are absent.     

Quaternary stratigraphy of the Koratallaiyar-Cooum basin,Chennai

In this paper we present Quaternary stratigraphy of the area around Chennai based on archaeological findings on the ferricrete surface, geomorphological observations supplemented by radiocarbon dating. The coastal landscape around Chennai, Tamil Nadu, has preserved ferruginised boulder gravel deposits, ferricretes and fluvial deposits of varying thickness. The area studied is approximately 150 km east to west and 180 km north to south with a broad continental shelf towards the seaward. Several rivers enter the Bay of Bengal along its shores like the Koratallaiyar, Cooum and the Adyar. Precambrian charnockite and Upper Gondwana sandstone and shale bedrock rim the shelf margin. For the most part, the Upper Pleistocene-Holocene fluvial sediments overlie an erosion surface that has cut into older Pleistocene sediments and ferricrete surface. Incised valleys that cut into this erosion surface are up to 5–6 km wide and have a relief of at least 30 m. The largest valley is that cut by the Koratallaiyar River. Holocene sediments deposited in the incised valleys include fluvial gravels, early transgressive channel sands and floodplain silts. Older Pleistocene sediments are deposited before and during the 120-ka high stand (Marine isotope stage 5). They consist of ferricretes and ferricrete gravel formed in nearshore humid environments. Muddy and sandy clastic sediments dated to the ca. 5 ka highstand suggest that the climate was semi arid at this time with less fluvial transport. The coarsening up sequence indicates deposition by high intensity channel processes. Pedogenic mottled, clayey silt unit represents an important tectonic event when the channel was temporarily drained and sediment were sub aerially exposed. Uplift of the region has caused the local rivers to incise into the landscape, forming degradation terraces.     

Stratigraphy and palaeoenvironmental development of Quaternary coarse clastic beach deposits at Plage de Mezpeurleuch,Brittany (France)

Quaternary deposits are described from well‐exposed sections in cliffs at Plage de Mezpeurleuch, Finistère, Brittany (France). The general lithostratigraphic sequence comprises Holocene perched dune sand, calcrete and palaeosol overlying Weichselian head and coarse clastic palaeobeach units attributed to the last interglacial (Eemian–isotope substage 5e). A lower and an upper palaeobeach, separated by a thin head deposit, are reported resting on an irregular palaeorock platform eroded in Hercynian granite. From a comparison with modern coastal environments a palaeoenvironmental interpretation of the palaeobeach deposits is made. Erosionally bounded facies of the lower palaeobeach, are considered to be a transgressive sequence preserved by drowning associated with a rapid rise in relative sea‐level. Its subsequent abandonment is attributed to a relative sea‐level fall, which allowed a terrestrial environment to develop briefly. Facies of the upper palaeobeach however indicate a prograding shoreline developed during a prolonged period of relatively stable sea‐level. These sea‐level observations are in good agreement with other evidence for a brief widespread intra‐Eemian cold event. Copyright © 2001 John Wiley & Sons, Ltd.     

Late Quaternary environmental phases in the Eastern Cape and adjacent Plettenberg Bay-Knysna region and Little Karoo, South Africa

Four major climato-environmental phases have been identified in the Eastern Cape, Plettenberg Bay-Knysna region and Little Karoo between somewhat before ∼40 000 cal. a BP and the present: the Birnam Interstadial from before 40 000 cal. a BP until ∼24 000 cal. a BP; the Bottelnek Stadial (apparently equating with the Last Glacial Maximum) from ∼24 000 cal. a BP until before ∼18 350 cal. a BP; the Aliwal North (apparently equating with the Late Glacial) from before ∼18 350 cal. a BP until ∼11 000 cal. a BP; the Dinorben (apparently equating with the Holocene) from ∼11 000 cal. a BP until the present. The evidence for, and the characteristics of, these phases is briefly described.     

Late Quaternary dietary shifts of the Cape grysbok (Raphicerus melanotis) in southern Africa

The Cape grysbok is endemic to southern Africa's Cape Floral Region where it selectively browses various species of dicotyledonous vegetation. Fossil evidence indicates that the grysbok persisted under glacial and interglacial conditions throughout the late Quaternary and inhabited a range of environments. This study employs mesowear analysis to reconstruct grysbok diets over time and in response to changing environments at Nelson Bay Cave, Die Kelders Cave 1, Klasies River Mouth, and Swartklip 1. Results indicate that the amount of grasses (monocots) versus leafy vegetation (dicots) included in the diet fluctuated over time and largely in agreement with changes in faunal community structure. The case for dietary flexibility is particularly clear at Nelson Bay Cave, where there is a significant trend from mixed feeding towards increased browsing from the late Pleistocene (~ 18,500 ¹⁴C yr BP) through the Holocene. Dietary shifts at Nelson Bay Cave are consistent with the hypothesis that declining grassland productivity is responsible for the terminal Pleistocene extinction of several large ungulates in southern Africa. Furthermore, the short-term dietary shifts demonstrated here (100s to 1000s of years) provide an important caution against relying on taxonomic uniformitarianism when reconstructing the dietary preferences of fossil ungulates, both extant and extinct.     

Glacial meltwater impounding: Evidence from the late Quaternary glaciogenic sediments in the Sangla valley, district Kinnaur, Himachal Pradesh, India

Sangla valley is situated at an altitude of ~ 3500 m above mean sea level and lies in the Kinnaur district of Himachal Pradesh. It is fed by river Baspa, a tributary of river Sutlej, that entrenches through the Quaternary glaciogenic deposits before emerging out of the valley and joining the river Sutlej at Karcham. The unstratified to stratified glaciogenic deposits consist of large boulders to fine silt and are classified into four major depositional facies on the basis of sedimentary texture and depositional environment. The facies — basal conglomerates, debris flow, water/sheet flow and laminites — represents the change in the environment of deposition from glaciofluvial to lacustrine and also the extent of the glacier to the valley floor during late Quaternary.     

南海西沙海域西科1井第四系生物礁: 碳酸盐岩成岩作用特征

以西科1井第四系乐东组生物礁-碳酸盐岩地层为研究对象, 通过偏光显微镜观察、茜素红-S和铁氰化钾混合溶液染色、扫描电镜和矿物阴极发光性观察等分析方法研究了生物礁-碳酸盐岩的岩石学和成岩作用特征.西科1井生物礁-碳酸盐岩成岩作用包括较弱的压实作用、新生变形作用、微生物泥晶化作用、溶解作用、胶结作用.以典型胶结物岩相学产状为标志, 结合矿物阴极发光性特征识别出了大气水和海水成岩环境.其中, 大气水成岩环境以典型的新月形或悬垂形方解石胶结物为识别标志, 海水成岩环境以纤维状-针状文石为识别标志.成岩环境的垂向分布表现为: 0~27 m深度内为显著的大气水成岩环境; 27~42 m深度内以大气水成岩环境为主, 其次为海水成岩环境; 42~105 m深度内以大气水成岩环境为主, 海水成岩环境的影响弱; 105~172 m深度内大气水和海水成岩环境均出现; 172.00~214.89 m深度内为海水成岩环境.      

Quaternary eolian dunes in the Savannah River valley,Jasper County,South Carolina,USA

Sand hills in the Savannah River valley in Jasper County (South Carolina, USA) are interpreted as the remnants of parabolic eolian dunes composed of sand derived from the Savannah River and stabilized by vegetation under prevailing climate conditions. Optically stimulated luminescence ages reveal that most of the dunes were active ca. 40 to 19 ka ago, coincident with the last glacial maximum (LGM) through early deglaciation. Modern surface winds are not sufficient for sustained eolian sand transport. When the dunes were active, winds blew at velocities of at least 4 m/s from west to east, and some vegetation was present. The ratio of annual precipitation to potential evapotranspiration (P:PE) was less than the modern ratio of 1.23 and may have been < 0.30, caused by stronger winds (which would have resulted in greater evaporation) and/or reduced precipitation. The Savannah River dunes are part of a larger assemblage of eolian dunes that were active in the eastern United States during and immediately after the LGM, suggesting that eolian sediment behavior in this region has been controlled by regional forcing mechanisms during the Quaternary.     

Microscopic charcoal in sediments: Quaternary fire history of the grassland and savanna regions in South Africa

The microscopic charcoal content of several Quaternary pollen sequences is used to investigate fire history in South Africa both during the Holocene and the Late Pleistocene. Although fluctuations in charcoal composition are recorded, it is difficult to link them directly to either human‐made or natural fires. Strong long‐term variations in microscopic charcoal of Middle and Upper Pleistocene layers are independent of pollen indications of past temperature and moisture conditions. Holocene charcoal sequences from different areas show no correlation, so no phases of regional burning are found. Some fluctuations in charcoal probably are the result of local burning in the various regions. The arrival of Iron Age people some 2000 yr ago apparently did not coincide with widespread wild fires, as these events do not consistently appear in regional microscopic charcoal records. The only exception appears to be the Wonderkrater spring deposit. Relatively open savanna environments, which are implied by pollen analysis at some sites during this period and the generally low microscopic charcoal contents, were either caused by climate change or controlled burning by Iron Age people. Copyright © 2002 John Wiley & Sons, Ltd.     

Occurrence of volcanic ash in the Quaternary alluvial deposits,lower Narmada basin,western India

This communication reports the occurrence of an ash layer intercalated within the late Quaternary alluvial succession of the Madhumati River, a tributary of the lower Narmada River. Petrographic, morphological and chemical details of glass shards and pumice fragments have formed the basis of this study. The ash has been correlated with the Youngest Toba Tuff. The finding of ash layer interbedded in Quaternary alluvial sequences of western Indian continental margin is significant, as ash being datable material, a near precise time-controlled stratigraphy can be interpreted for the Quaternary sediments of western India. The distant volcanic source of this ash requires a fresh re-assessment of ash volume and palaeoclimatic interpretations.     

Vegetation history inferred from pollen in Late Quaternary faecal deposits (hyraceum) in the Cape winter-rain region and its bearing on past climates in South Africa

Pollen analysis shed light on vegetation community structure over the last 23,000 year in the western Cape. The pollen from dated hyrax faecal accumulations (hyraceum) relates to the evolution of climate and contributes to proxy records in southern Africa. Principal components analyses of the pollen data and δ¹³C values of the hyrax dung samples show millennial and shorter scale temperature, moisture and seasonality variations in the winter rain region. The moisture availability at times do not parallel that in previously studied proxy records in the summer rain region showing an asynchronous moist event in the early Holocene and drier conditions in the Middle Holocene. Anomalies in climate between the two regions may depend on the degree of northward or southward shifting of winter- and summer-rain circulation systems. Scenarios with winter-rain or cool growing seasons mostly typify the dung sequence but do not exclude the possibility of southward displacement of the westerly belt under precessional strength with slight summer rain increases during the Last Glacial Maximum. Limited southward displacement is also possible during the Mid Holocene.     

Geomorphological palaeoenvironments of the Sneeuberg Range,Great Karoo,South Africa

Sedimentary sequences within headwater valleys on the landward side of the Great Escarpment of South Africa are elucidated and their significance as indicators of environmental change is assessed. This study focuses on the Sneeuberg Range, the most prominent mountain range in the semi‐arid central Great Karoo. Valley fills of a hitherto unrecognised complexity and of a greater age than any previously recorded in the central Great Karoo are reported. Three phases of deposition spanning the Late Pleistocene up to the present are documented from sites where gully erosion has incised the valley fills. The earliest depositional phase is represented by deeply weathered, calcretised gravel deposits, which probably were emplaced by debris flow and fluvial processes in the form of a fan. These deposits subsequently were buried by finer grained, largely unconsolidated sediment, with much of this emplacement occurring during the Holocene. There is evidence for phases of landscape stability and instability within this facies. Finally, sheetwash has removed fine‐grained sediments from valley flanks and has deposited it either on valley bottoms, or in presently active gullies. This process appears to be ongoing, and is the subject of current investigation. The sedimentary deposits are interpreted as representing a wide range of palaeoenvironmental conditions that have prevailed within the central Great Karoo since the penultimate glaciation. Copyright © 2003 John Wiley & Sons, Ltd.