Pollen records and age determination of site Bokanjacko Blato

In summary, one may conclude that human influence in the Bokanjac area started in the Eneolithic or Earlier Bronze Age - the third to second millennia Cal. BC. Traces of agriculture are weak or missing in the pollen diagram but grazing is indicated. Chestnut and walnut were introduced by humans to the area in classical times. These findings are in general agreement with the results of earlier studies at coastal sites north-west and south-east of Bokanjacko Blato.

Age determination of sediment from Lake Komi

Beach and shoreface sediments deposited in the more than 800-km long ice-dammed Lake Komi in northern European Russia have been investigated and dated. The lake flooded the lowland areas between the Barents-Kara Ice Sheet in the north and the continental drainage divide in the south. Shoreline facies have been dated by 18 optical stimulated luminescence (OSL) dates, most of which are closely grouped in the range 80-100 ka, with a mean of 88 +/- 3 ka. This implies that that the Barents-Kara Ice Sheet had its Late Pleistocene maximum extension during the Early Weichselian, probably in the cold interval (Rederstall) between the Brørup and Odderade interstadials of western Europe, correlated with marine isotope stage 5b. This is in strong contrast to the Scandinavian and North American ice sheets, which had their maxima in isotope stage 2, about 20 ka. Field and air photo interpretations suggest that Lake Komi was dammed by the ice advance, which formed the Harbei-Harmon-Sopkay Moraines. These has earlier been correlated with the Markhida moraine across the Pechora River Valley and its western extension. However, OSL dates on fluvial sediments below the Markhida moraine have yielded ages as young as 60 ka. This suggests that the Russian mainland was inundated by two major ice sheet advances from the Barents-Kara seas after the last interglacial: one during the Early Weichselian (about 90 ka) that dammed Lake Komi and one during the Middle Weichselian (about 60 ka). Normal fluvial drainage prevailed during the Late Weichselian, when the ice front was located offshore.

Pollen record and age determination of a sediment profile from Frengstadsetra, Norway

Innerdalen was once a mountain valley (ca. 780 m a.s.l.) with birch forests, bogs and several summer farms. Today it is a 6.5 km**2 artifical lake. In 1980 and 1981 archaeological and palynological investigations were carried out due to the hydroelectric power plans. Radiocarbon dated pollen diagrams from 9 different localities in Innerdalen provide information on a mountain environment which has been exploited to varying degrees by human groups for thousands of years. In the Birch Zone, ca. 9500-8500 years B.P., the deglaciated surface is vegetated by the normal sequence of pioneering species, first show-bed communities, then shrub/dwarf-shrub communities, and finally a birch forest community. In the Pine Zone, ca. 8500-7500 years B.P., the mixed Birch-Pine forest which prevailed at the end of the Birch Zone is replaced by a dense pine forest. The tree limit was higher than it is today. In the Alder Zone, ca. 7500-4000 years B.P., the newly arrived alder gradually succeeded pine, particularily on good soils. This alder forest has a modem analog in the pre-alpine gray alder forests in Norway. In the last part of the Alder Zone, ca. 6000-4000 years B.P., elm and hazel are nominally present on particularily rich soils, marking the edaphic and climatic optimum in Innerdalen. During this time the first evidence of human impact on the vegetation is apparent in the pollen diagrams. At both Sætersetra in the south of the valley and Liabekken in the north, forest clearance and the development of grazed grass meadows is documented, and human impact continues until the present. The Herb Zone, ca. 4000 years B.P. to 1600 A.D., is characterized by the rapid decline of alder. The forest is increasingly open, and bog formation is initiated. The sub-alpine belt of birch forest is established, probably due to the shift to a cooler, moister climate. Human activity can also have influenced the vegetational changes, although at 4 of the localities human activity also is first apparent after the alder decline. Some localities show measurably less human impact on the vegetation ca. 2600-2000 years B.P. Grazing intensity increases ca. 2000 years B.P. At the end of the Herb Zone rye and barley pollen is registered at Sætersetra and Flonan, indicating contact between the grazing activities of Innerdal and grain cultivation activities outside the valley. The Spruce Zone, ca. 1600 A.D. to the present, does not begin synchronously since the presence of long-distance transported spruce pollen at a locality is entirely dependent on the density of the vegetation ie. degree of human impact. The youngest spruce rise is ca. 1500 A.D. at Røstvangen, when summerfarming is initiated. Summerfarming activities in Innerdal produce an increasingly open landscape. Rye and barley pollen at several localities may indicate limited local cultivation, but is more likely long-distance transport via humans and domesticated animals from cultivated areas outside Innerdalen.

Pollen record and age determination of a sediment profile from Schmiechener See, Germany

Die untersuchten Schluffe und Kiese sind unter kaltzeitlichen Bedingungen in einem See mit Schwimmpflanzengesellschaften abgelagert worden. Zur Sedimentationszeit gab es in der Umgebung des Sees eine tundrenartige Vegetation, die auch Steppenarten enthielt.

Age determination of the rhyolites of the Lord Howe Rise in the Southwest Pacific Ocean

Drilling at site 207 (DSDP Leg 21), located on the broad summit of the Lord Howe Rise, bottomed in rhyolitic rocks. Sanidine concentrates from four samples of the rhyolite were dated by the 40Ar/39Ar total fusion method and conventional K-Ar method, and yielded concordant ages of 93.7 +/- 1.1 my, equivalent to the early part of the Upper Cretaceous. At this time the Lord Howe Rise, which has continental-type structure, is thought to have been emergent and adjacent to the eastern margin of the Australian-antarctic continent. Subsequent to 94 my ago and prior to deposition of Maastrichtian (70-65 myBP) marine sediments on top of the rhyolitic basement of the Lord Howe Rise, rifting occurred and the formation of the Tasman Basin began by sea-floor spreading with rotation of the Rise away from the margin of Australia. Subsidence of the Rise continued until Early Eocene (about 50 myBP), probably marking the end of sea-floor spreading in the Tasman Basin. These large scale movements relate to the breakup of this part of Gondwanaland in the Upper Cretaceous.

Geochemistry and age determination of zircons in Cretaceous to Quaternary sediments

In central Antarctica, drainage today and earlier back to the Paleozoic radiates from the Gamburtsev Subglacial Mountains (GSM). Proximal to the GSM past the Permian-Triassic fluvial sandstones in the Prince Charles Mountains (PCM) are Cretaceous, Eocene, and Pleistocene sediment in Prydz Bay (ODP741, 1166, and 1167) and pre-Holocene sediment in AM04 beneath the Amery Ice Shelf. We analysed detrital zircons for U-Pb ages, Hf-isotope compositions, and trace elements to determine the age, rock type, source of the host magma, and "crustal" model age (T(C)DM). These samples, together with others downslope from the GSM and the Vostok Subglacial Highlands (VSH), define major clusters of detrital zircons interpreted as coming from (1) 700 to 460 Ma mafic granitoids and alkaline rock, epsilon-Hf 9 to -28, signifying derivation 2.5 to 1.3 Ga from fertile and recycled crust, and (2) 1200-900 Ma mafic granitoids and alkaline rock, epsilon-Hf 11 to -28, signifying derivation 1.8 to 1.3 Ga from fertile and recycled crust. Minor clusters extend to 3350 Ma. Similar detrital zircons in Permian-Triassic, Ordovician, Cambrian, and Neoproterozoic sandstones located along the PaleoPacific margin of East Antarctica and southeast Australia further downslope from central Antarctica reflect the upslope GSM-VSH nucleus of the central Antarctic provenance as a complex of 1200-900 Ma (Grenville) mafic granitoids and alkaline rocks and older rocks embedded in 700-460 Ma (Pan-Gondwanaland) fold belts. The wider central Antarctic provenance (CAP) is tentatively divided into a central sector with negative ?Hf in its 1200-900 Ma rocks bounded on either side by positive epsilon-Hf. The high ground of the GSM-VSH in the Permian and later to the present day is attributed to crustal shortening by far-field stress during the 320 Ma mid-Carboniferous collision of Gondwanaland and Laurussia. Earlier uplifts in the ~500 Ma Cambrian possibly followed the 700-500 Ma assembly of Gondwanaland, and in the Neoproterozoic the 1000-900 Ma collisional events in the Eastern Ghats-Rayner Province at the end of the 1300-1000 Ma assembly of Rodinia.

Pollen record and age determination of sediment core Fersina 2

Pollen analysis of samples taken from the core of the water well Fersina 2 (Adige Valley, Prov. Trento, NE Italy) did not reveal any indication of an interglacial or Holocene age of the uppermost 190 m in the sediment sequence deposited in the over-deepened Adige River Valley. The sediment sequence dates entirely from late-glacial times. Four radiocarbon ages of pieces of wood indicate that about 165 m of the upper part of the profile are of Younger Dryas age. The lower part of the sequence dates from the Allerød or Bølling/Allerød and a preceding cold phase, probably the Oldest Dryas. Accordingly the deposition of the sequence took about 2500 or 3500 years and was completed long before the onset of the Neolithic. Our results are in excellent agreement with findings in other formerly glaciated alpine valleys (e.g. the Traun, Salzach and Enns valleys in the Northern Alps). The final depth of the Fersina 2 well is 190 m. It is very likely that the sediment sequence found below this level in the nearby 423 m deep Fersina 1 well was also deposited after the deglaciation of the Adige Valley at the end of the last glacial period.

K-Ar age determination of Paleozoic rock samples from northern Victoria Land, Antarctica

K-Ar ages of 82 slate and schist (white-mica-rich whole rock) samples are reported for Late Precambrian-Early Ordovician metamorphic rocks of the Wilson, Bowers and Robertson Bay terranes of northern Victoria Land. These are amalgamated in two vertical sections along composite NE-SW horizontal profiles across (1) Oates Coast in the north, and (2) Terra Nova Bay area in the south. The ages are in the range 328-517 Ma. Both profiles show some age variation with altitude, but more importantly, they define an inverted wedge shaped pattern, reflecting a "pop-up" strucure. This is oriented NW-SE at the eastern margin of the Wilson terrane, and the edges coincide with the Exiles and Wilson Thrusts which cross the region. Ages inside the "pop-up" structure are younger, ca. 460-480 Ma, than those along its eastern and western flanks, ca. 490-520 Ma. The K-Ar age patterns thus demonstrate a late Ross Orogenic age (ca. 460 Ma) for this structure, which may be associated with assembly of the Wilson and Bowers terranes.

Age models of sediment cores from the continental margin of northwest Africa

Diatom abundance and species composition were quantitatively studied in two latest Quaternary (~130 ka to the Present) sequences from the continental margin of northwest Africa. Off this region, coastal upwelling is well developed under the influence of the NE trade winds. Variations in diatom abundance in these cores are inferred to represent changes caused by varying degrees of the upwelling fertility. Times of high productivity are marked by high relative frequencies of Chaetoceros, while low productivity is marked by the dominance of Aulacoseira granulata. Upwelling increased during glacial episodes (isotopic stages 2-4 and 6) relative to isotopic stages 1 and 5. During the late Holocene, primary productivity levels are similar to those for Stage 5, but in the early Holocene upwelling intensities seem to have been weaker than today. The paleoproductivity reconstruction based on the diatom record is supported by paleoproductivity estimations based on the organic carbon content of the sediments (Sarnthein et al., 1987).

Pollen profile and age determination of sediment core Schwanengrabenrinne, Brandenburg, Germany

In der Döberitzer Heide nördlich von Potsdam wurden vegetationsgeschichtliche Untersuchungen durchgeführt. Das Untersuchungsgebiet befindet sich im östlichen Teil der Nauener Platte, die bisher vegetationsgeschichtlich weitgehend unerforscht war. In sechs verschiedenen Mooren wurden acht Bohrungen niedergebracht. Die Bohrkerne wurden stratigraphisch und pollenanalytisch untersucht und für die Radiocarbondatierung beprobt. Die Pollendiagramme ermöglichen die Rekonstruktion der Vegetationsentwicklung der terrestrischen Standorte und der Moore in der Döberitzer Heide in den letzten 14.000 Jahren. Neben einer Revision der Gliederungsprinzipien der spätglazialen Vegetationsentwicklung Brandenburgs und einer vergleichenden Betrachtung der Moorentwicklung in der Döberitzer Heide wurde besonderes Augenmerk auf die Geschichte des Döberitzer Lindenwaldes gerichtet, der einen Sonderfall in der brandenburgischen Vegetation darstellt. Die Untersuchungen boten die Möglichkeit, die Ursachen seiner Entstehung zu klären, Aussagen zu den Perspektiven seiner Entwicklung zu treffen und mögliche Entwicklungspotentiale von Lindenwäldern im Land Brandenburg aufzuzeigen.

Age determination of Paleogene sediments from the Prysz Bay

Age dating of Paleogene diamictites from ODP Site 739 in Prydz Bay with marine microfossils (diatoms and calcareous nannofossils) suggests the build-up of a major East Antarctic ice shield in latest Eocene to earliest Oligocene time, about 35-38 m.y. ago. Strontium isotopic analyses of small mollusk remains found within these diamictites, however, yield younger ages ranging from 29 to 23 Ma (i.e., latest early Oligocene to earliest Miocene). These age discrepancies could be caused by repeated glacial reworking of microfossils, macrofossils, and sediment clasts through the late Oligocene or, alternatively, by ion exchange in the still aragonitic mollusk shells.

Age determination of sediment cores from the continental shelf and slope off North-West Africa

Three sediment cores from the continental shelf and slope off NW Africa (Banc d'Arguin; 52 m, 665 m and 973 m water depth) have been investigated by means of a coarse fraction analysis. The two shallower cores have been deposited during less than 10,000 years, the deeper one during the last 36,000 years. The Holocene sedimentation ( 4000 years) in the deeper part of core 79 the edge of the Banc d'Arguin is strongly influenced by reworking of Late Glacial dune sands and biogenic particles from shallower ware (<40 m), as well as eroding current influence. A decrease in grain size of silicate material and a decrease in lateral supply, correlated to a doubling of accumulation rates in the upper part of the core, indicates a more autochthonous sedimentation with less sorting influence in the youngest Holocene. The depth of provenance of the allochttonous material can be assumed in 100-300 m water depth as indicated by various biogenous particles. Small amounts of shallow water particles in the autochthonous layers indicate a supplay from shallow water, which probably occured b ythe mechanism of "particle by particle supply". None of the three cores indicates upwelling influence, although occanographers found intense upwelling in the area of the Banc d'Arguin. The Holocene climate in that area probably has been arid, small variations in terrigenous matter composition and grain size in the Early Holocene might be due to decreased wind strength or to an increase in rain fall. The Peak Glacial section (14,000-22,000 y. B.P.) of the deepest core 88 indicates a very much intensified eolian silt supply and an additional bottom supply of quartz sand In the interval 22,000-36,000 y. B.P. wind strength decreased, but probably no increase in humidity occurred. So this area in about 19° 40' N had an arid climate in the Late Holocene and in the Peak Glacial. The fragmentation of planktonic foraminifers and the abundance of aragonitic tests of pteropods in core 88 indicate an Early Holocene (8330 y. B.P.) preservation spike. Two minima in fragmentation correlated to maxima in pteropod content at about 15,700 and 21,000 y. B.P. are correlated to maxima in shallow water supply and thus do not reflect preservation conditions, but only lateral supply from the carbonate dissolution minimum zone in about 300 m water depth.

(Table 2) Number of identified specimens and individuals from bones and bone fragments at site IbGk-3, Drayton Island

An interdisciplinary study was conducted at Qijurittuq (IbGk-3), an archaeological site located on Drayton Island along the eastern shore of Hudson Bay, Nunavik. Local Inuit made important contributions to the research. High school students participated in the field school, and elders shared their traditional knowledge. The elders expressed an interest in the source of the wood used to construct Qijurittuq's semi-subterranean dwellings, and this inspired us to expand our research in that direction. This interdisciplinary study included a reconstruction of the geomorphological and environmental history of Drayton Island, wood provenance and dendrochronology studies, research on house architecture and settlement patterns, and a zooarchaeological analysis. This paper synthesizes the preliminary results of this interdisciplinary investigation within the context of climate change. We discuss the persistence of semi-subterranean dwellings in eastern Hudson Bay long after they had been abandoned elsewhere. At Qijurittuq, their abandonment corresponds with the end of Little Ice Age. However, at the same time, the development of more permanent contact with Euro-Canadians was having a strong impact upon Inuit culture.

Pollen record and age determination of a sediment core from the Kara Sea

AMS-14C dated sediment cores from the Ob and Yenisei estuaries and the adjacent inner Kara Sea were investigated to determine the siliclastic and organic carbon fluxes and their relationship to paleoenvironmental changes. The variability of sediment fluxes during Holocene times is related to the post-glacial sea-level rise and changes in river discharge and coastal erosion input. Whereas during the late/middle Holocene most of the terrigenous sediments were deposited in the estuaries and the areas directly off the estuaries, huge amounts of sediments accumulated on the Kara Sea shelf farther north during the early Holocene before about 9 Cal. kyrs. BP. The maximum accumulation at that time is related to the lowered sea level, increased coastal erosion, and increased river discharge due to the final stage of mountain deglaciation of the Putoran Massif. Increased supply of Yenisei-derived material indicated by peak magnetic susceptibility values probably occurred in climate-related pulses culminating near 11, 10, and 9 Cal. kyrs. BP. As sea level rose, the main Holocene depocenter migrated southward. Based on hydrogen index values and n-alkanes, the organic matter is predominantly of terrigenous origin. Maximum accumulation rates of 1.5 to more than 6 g/cm2/y occurred in the early Holocene sediments, suggesting more humid climatic conditions with an increased vegetation cover in the source area at that time. In general, high organic carbon accumulation rates characterize the estuaries and the inner Kara Sea as important sink for terrigenous organic carbon. A high-resolution record of Holocene variability of magnetic susceptibility (MS) in an AMS14C-dated sediment core from the northern Yenisei estuary may indicate natural variability of Arctic climate change and river discharge on a centennial to millenial time scale. Short-term maxima in MS probably related to warmer climate, enhanced precipitation, intensified weathering/erosion and increased river discharge, display a frequency of about 300 to 700 years.