Glacial forest refugium in Howard Valley,South Island,New Zealand

Fossils of forest habitat beetles and leaves of Nothofagus menziesii provide evidence of a forest refugium at times between ca. 34 000 and ca. 18 500 cal. a BP at an upland site in Howard Valley, located adjacent to glaciated valleys in South Island, New Zealand. The stratigraphy of the glacial‐aged terrace sequence of organic‐rich silts and fluvial sand/gravels indicates that soil development occurred episodically for around 15 000 a. Fifty‐four beetle taxa represent seven habitat types: forest, forest or scrub, riparian and aquatic, litter, grass/tussock, marshland and moss habitats. Leaf and beetle fossils indicate that forest dominated by N. menziesii persisted at the site for most of the time period represented, and tree line taxa such as Taenarthrus sp. 1 (Carabidae) and Podocarpus sp. (Podocarpaceae) indicate that the site may represent the upper tree limit for full‐glacial time. The finding of forest at this elevated site adds to the growing fossil evidence for multiple forest refugia in New Zealand during the last glaciation and is consistent with the pollen records, which have consistently indicated the presence of forest species during the last glaciations. Copyright © 2009 John Wiley & Sons, Ltd.     

Late Wisconsin climate in northeastern USA and southeastern Canada,reconstructed from fossil beetle assemblages

Mean July and January temperatures are reconstructed from radiocarbon-dated fossil beetle assemblages, yielding a synthesis of palaeoclimatic history of the regions south of the Laurentide Ice Sheet in North America from 35 000 to 8500 yr BP. Mean July temperatures close to the last glacial maximum were 11–12°C colder than present; mean January temperatures were possibly 10–19°C colder. Mutual climatic range analyses of the beetle assemblages show warming of mean summer temperatures as early as 13.7 kyr, although ice-proximal sites were consistently about 5°C cooler than ice-distal sites. Late-glacial mean summer temperatures peaked between 12 and 11 kyr, then remained fairly constant through the early Holocene. Mean winter temperatures did not reach modern values until after 10 kyr.     

Late Quaternary climatic history of the Chilean Channels based on fossil pollen and beetle analyses,with an analysis of the modern vegetation and pollen rain

Fossil beetles and pollen were examined from an intermorainal bog at Puerto Edén, Isla Wellington, Chile (latitude 49°08'S, longitude 74°25'W). Wood from near the base of the section has an age of 12 960 ± 150 yr BP. Occurrence of flightless beetle species in the basal peat sample is evidence that some members of the biota survived the last glacial maximum in refugia. The assumption that the Chilean Channels were entirely ice-covered is incorrect. Plants and insects that invaded the deglaciated terrain were those of an Empetrum heathland in which patches of Nothofagus forest were restricted to sheltered locations. The climate supporting the heathland is inferred to have been windier and probably drier than that of the present day. From 13 000 yr BP to 9500 yr BP Nothofagus forest expanded, possibly in response to less windiness and more available moisture. Neither the fossil beetle nor pollen data support a return to significantly colder conditions between 11 000 and 10 000 yr BP at the time of the Younger Dryas Stade. From 9500 to 5500 yr BP the climate was as wet as that of the present day, based on an increased representation of the pollen of moorland plants and of aquatic beetle species. From 5500 to 3000 yr BP the climate was drier, as indicated by the expansion of Empetrum heath and the reduction in mesic habitats. From 3000 yr BP to the present-day mesic habitats dominated as the climate returned to a wetter mode. The alternatively wetter and drier episodes are attributed to latitudinal shifts in the position of storm tracks in the belt of Southern Westerlies.     

Palaeoenvironmental interpretation of Middle and Late Wisconsinan fossil coleopteran assemblages from western Olympic Peninsula,Washington, USA

Organic sediments exposed in a seacliff near Kalaloch, Washington, contain abundant, well-preserved beetle remains. Fossil assemblages dating from about 48 000 to 40 000 yr BP are dominated by species typical of the lowland and montane forests in the region today. A few species, Micropeplus laticollis, Olophrum consimile, Olophrum boreale, Arpedium cribratum, and Tachinus thruppi are presently not members of the Pacific Northwest fauna. Mean July temperature during this part of the Middle Wisconsinan is estimated to have been about 1°C lower than today. Later Wisconsinan assemblages are dominated by non-arboreal species, indicating a treeless, probably tundra environment. Mean July temperature based mostly on the occurrence of the alpine leaf-beetle species, Asiorestia pallida, is estimated to have been at least 3°C lower than the present day. Palaeoclimatic interpretations based on beetles are in good agreement with those based on pollen.     

Stratigraphy,pollen and 14C dating of Johnston's Gum Hole,a late Quaternary fossil kauri (Agathis australis) site,Northland, New Zealand

Johnston's Gum Hole provides a discontinuous pollen record commencing late in Marine Isotope Stage 5 (MIS 5). In combination with other published records from the region, the Aupouri Peninsula is reconstructed to have been continuously forested through much of the last glacial cycle with the oscillation of Agathis‐ and Nothofagus‐dominated forest corresponding to stadials and interstadials, respectively. A northward latitudinal expansion of beech forest to 35° S is demonstrated. Kauri demise at the close of MIS 5 appears to have been due to flooding of the site. The elimination of kauri in MIS 3 was also associated with rewetting of the substrate, but could have been a more catastrophic event. The presence of both MIS 5 and MIS 3 kauri wood at the site suggests that other Aupouri peat swamps may also preserve timber of these ages, and demonstrate the potential of this area for providing MIS 3 and MIS 5 tree ring records. Copyright © 2008 John Wiley & Sons, Ltd.     

MIS3晚期石笋记录的季风突变事件区域特征及全球联系

末次冰期晚期短尺度气候突变事件异常显著,对其研究有助于认识相似边界条件下气候突变规律。通过MIS3晚期亚洲季风区8支石笋记录总结分析发现,因受洞穴微环境、渗水通道、生长动力等影响,DO5~DO3事件振幅差最大可达0.9 ‰,持续时间差最大达到900年,这可能反映局地环境对同一气候信号的改造作用或与各记录分辨率及测年精度有关。同时,统计分析发现,这些短尺度DO事件具有一定相似性,其持续时间集中分布于特定范围,说明石笋同位素信号在某种程度上可以反映真实气候信号。高、低纬记录对比显示,石笋记录与低纬气候信号呈现诸多相似性,反映亚洲季风区石笋记录具有显著的"低纬特色"。因此,无论亚洲季风突变的"开关"是否归因于北高纬气候,低纬过程确实是不可或缺的"塑造者"。

     

哈萨克斯坦Tramplin剖面孢粉记录的MIS3a环境变化

利用AMS ¹⁴C测年,通过对哈萨克斯坦南部Tramplin黄土-古土壤沉积剖面的孢粉分析,揭示了中亚干旱区深海氧同位素(MIS)3a阶段植被和气候演化历史：41.4 ka B.P.以前,植被为蒿属植物占优势的荒漠草原,气候干旱; 41.4～40  ka B.P.,植被为蒿草草原,气候湿润程度增加;40～36  ka B.P.,植被为蒿属植物占优势的荒漠草原,气候湿润程度轻微下降;36～33  ka B.P.,植被为蒿草草原,气候湿润程度增加;33～30  ka B.P.,植被为蒿属植物占优势的荒漠草原,湿润程度轻微下降;30～28 ka B.P.,植被为蒿草草原,气候湿润程度轻微上升。     

中国西部山岳冰川MIS3b冰进的初步探讨

对横断山的沙鲁里山、祁连山东段的冷龙岭、天山西段托木尔峰南麓的阿特奥依纳克河流域等3个地区7个研究点的第四纪冰川作用开展了深入研究,应用ESR测年技术在7个研究点特定的地貌部位共获得12个对应于MIS3(56~36 ka BP)的测年结果,且年龄基本上都对应于MIS3b(54~44 kaBP).结合已有的研究资料,并对MIS3气候特征进行综合分析,研究表明:MIS3强大的季风环流带来的丰富降水与MIS3b冷阶段的组合是川西高原的沙鲁里山与祁连山东段冷龙岭MIS3b冰进的主要原因,而天山西段阿特奥依纳克河流域MIS3b冰进则是不稳定的西风波动带来的丰富降水所致.这3个地区沉积有该次冰进的冰碛物.     

Helium and carbon isotope systematics of natural gases from Taranaki Basin,New Zealand

The chemical and isotopic compositions of gases from hydrocarbon systems of the Taranaki Basin of New Zealand (both offshore and onshore) show wide variation. The most striking difference between the western and south-eastern groups of gases is the helium content and its isotopic ratio. In the west, the Maui gas is over an order of magnitude higher in helium concentration (up to 190 μmol mol⁻¹) and its ³He/⁴He ratio of 3.8 R_A (where R_A=the air ³He/⁴He ratio of 1.4×10⁻⁶) is approximately half that of upper mantle helium issuing from volcanic vents of the Taupo Volcanic Zone. In the SE, the Kupe South and most Kapuni natural gases have only a minor mantle helium input of 0.03–0.32 R_A and low total helium concentrations of 10–19 μmol mol⁻¹. The ³He/C ratio (where C represents the total carbon in the gas phase) of the samples measured including those from a recent study of on-shore Taranaki natural gases are generally high at locations where the surface heat flow is high. The ³He/CO₂ ratio of the Maui gases of 5 to 18×10⁻⁹ is higher than the MORB value of 0.2 to 0.5×10⁻⁹, a feature found in other continental basins such as the Pannonian and Vienna basins and in many high helium wells in the USA. Extrapolation to zero CO₂/³He and CO₂/C indicates δ¹³C(CO₂) values between −7 and −5‰ close to that of MORB CO₂. The remaining CO₂ would appear to be mostly organically-influenced with δ¹³C(CO₂) c.−15‰. There is some evidence of marine carbonate CO₂ in the gases from the New Plymouth field. The radiogenic ⁴He content (He_rad) varies across the Taranaki Basin with the highest He_rad/C ratios occurring in the Maui field. δ¹³C(CH₄) becomes more enriched in ¹³C with increasing He_rad and hydrocarbon maturity. Because ³He/⁴He is related to the ratio of mantle to radiogenic crustal helium and ³He/C is virtually constant in the Maui field, there is a correlation between R_C/R_A (where R_C=air-corrected ³He/⁴He) and δ¹³C(CH₄) in the Maui and New Plymouth fields, with the more negative δ¹³C(CH₄) values corresponding to high ³He/⁴He ratios. A correlation between ³He/⁴He and δ¹³C(CO₂) was also observed in the Maui field. In the fields adjacent to Mt Taranaki (2518 m andesitic volcano), correlations of some parameters, particularly CO₂/CH₄, C₂H₆/CH₄ and δ¹³C(CH₄), are present with increasing depth of the gas reservoir and with distance from the volcanic cone.     

New remains of Pleistocene Ovibos moschatus from Germany and its geographic and stratigraphic occurrence in Europe

All remains of Pleistocene muskoxen from central and western Europe are attributable to a single species, Ovibos moschatus. Its occurrence was restricted mainly to the area north of the Pyrenees and Alps, covering lowlands and mountain areas up to 1600 m. In the Middle Pleistocene, Ovibos occurred in a cold phase, well before the Elsterian, and again during the Saalian and Weichselian. In the Late Pleistocene, Ovibos co-occurred with other faunal elements indicative of severe continental climatic conditions during the early and late Weichselian. During the middle Weichselian, the genus seems to have retreated. A list of European localities that have yielded Ovibos moschatus, inclusive of geographical references, is provided.     

MIS 3晚期以来江苏中部海岸的层序地层

通过对苏北岸外西洋潮流通道内钻孔和地震剖面的地层沉积学、年代地层学、地震地层学和层序地层学等多学科再研究,以及区域钻孔再对比,本文确定该海域约从35kaBP(14C惯用年龄)开始经历了滨岸砂坝、淡水湖沼、河流泛滥平原、滨岸沼泽、潮流沙脊和潮流通道一系列的环境演变,主要受控于MIS3晚期以来的海平面旋回以及古河流入海沉积物供给,而构造沉降是相对次要的,由此形成了五级层序地层中的末次冰期晚间冰阶准层序和冰后期准层序,以及前者的高水位体系域和强制海退楔体系域、后者的海侵体系域和高水位体系域。海域中潮流沙脊可能开始发育于冰后期海侵淹没本区(约9calkaBP)之后,但一直只是水下暗沙且处在不断调整之中,直到1128～1855AD间黄河夺淮从苏北入黄海,大量泥沙充填潮道,部分水下暗沙出露海面成为明沙。西洋潮流通道并非是晚全新世期间通过沙脊的蚀低而形成,而在全新世高海面前后就已具雏形并持续至1128AD,1128～1855AD和1855AD至今分别经历了充填淤浅与冲刷成型的过程,且今后具有进一步展宽刷深的趋势。     

辽西热河生物群中的水虿化石新发现

本文描述了热河生物群中2个水虿新种：Gomphus? biconuexus sp．nov,和Aeschna?acrodonta sp．nov．,它们分别属于Gomphidae科和Aeshnidae科。化石采自辽西北票黄半吉沟义县组下部(晚侏罗世-早白垩世早期)。     

Identification and significance of a late Pleistocene tephra in Canterbury district,South Island,New Zealand

A rhyolitic ash 4 to 8 cm thick is well preserved within a thick loess unit in a coastal section 2 km long near Teviotdale, Canterbury district, South Island, New Zealand. The ash (informally named Tiromoana ash) contains fresh glass shards which give a fission-track age of 20,300 ± 7100 yr B.P. The only possible source for such a tephra with this age range is from Taupo Volcanic Zone (TVZ), North Island, some 550 km north of Teviotdale. Within the time span ca. 15,000 to 42,000 yr B.P. five widespread and voluminous rhyolitic tephras (viz. Rerewhakaaitu Ash, Rotoehu Ash, Kawakawa Tephra, Omataroa Tephra, and Mangaone Tephra) were erupted from TVZ. On the basis of the fission-track age, ferromagnesian mineralogy, and electron-microprobe analyses of glass shards and titanomagnetites from Tiromoana ash and the five possible correlatives listed above, Tiromoana ash is correlated with Kawakawa Tephra (dated by ¹⁴C at ca. 20,000 yr B.P.). This is the only known occurrence to date of Kawakawa Tephra in the South Island. Its preservation is attributed to special site conditions (low precipitation and minimal sheet erosion) leeward of a prominent terrace. The identification of the ash at Teviotdale as Kawakawa Tephra supports recently revised age assignments for the upper loess sheet in Canterbury. Moreover, it implies that loess enclosing Kawakawa Tephra in nonglaciated districts of southern North Island and Taupo Volcanic Zone is a correlative.     

Paleobotanical analysis of materials from fossil gopher burrows and upper pleistocene host deposits, the Kolyma River lower reaches

The comparative analysis of palynomorphs and plant megafossils (fruits, seeds, twigs, leaves) in the Upper Pleistocene host sediments and materials filling in fossil burrows of gophers, their coprolites included, at the Duvannyi Yar, Stanchikovskii Yar and Zelenyi Mys sites of the Kolyma Lowland is carried out. Genera Salix, Lychnis, Silene, Draba, Potentilla, Larix, and families Poaceae, Polygonaceae, Cyperaceae, Compositae, and Leguminosae are determined among palynological remains and megafossils. Factors responsible for qualitative and quantitative differences in taxonomic compositions of palynological and megafossil assemblages are biological peculiarities of plants, different character of fossilization of palynomorphs and large plant remains, geographic conditions, different genesis of assemblages (allochthonous for microfossils and autochthonous for megafossils), and inadequately known morphology of certain spore and pollen taxa. The comprehensive paleobotanical analysis leads to the conclusion that the study region was occupied in the Late Pleistocene by plant communities of humid to somewhat dryer tundra with separate areas of pioneering and steppe vegetation.     

新疆艾里克湖炭屑记录的中亚干旱区MIS 3中期以来的古火灾演化

大规模火灾能够对当地植被和生产经济造成不可逆的损害, 严重影响着人们的生产生活。中亚干旱区生态系统脆弱, 火灾频发, 使得该地区成为研究古火灾的理想地区之一。MIS 3时期是距离现今最近的间冰阶, 气候上与现在有许多相似之处, 是进行古气候研究的重要时段。通过对长时间尺度上的火灾演化及其影响因素的了解, 即有助于我们理解火灾对植被和气候变化的响应机制, 又能够为现代预测和治理火灾提供一定的科学依据。本研究以新疆艾里克湖Ailike-2019孔(岩芯长4.49 m)沉积岩芯为研究对象, 通过AMS ¹⁴C测年、花粉通量和炭屑分析, 重建艾里克湖约40 ka以来的古火灾演化序列。结果表明, MIS 3中、晚期(40.2~26.7 cal.ka B.P.), 植被覆盖度较差, 火灾较少; MIS 2时期(26.7~11.7 cal.ka B.P.), 植被覆盖度差, 火灾少; 全新世(11.7 cal.ka B.P. 至今), 植被覆盖度显著上升, 火灾频发。研究区自MIS 3中期以来的火灾活动与植被覆盖度的变化具有相似的趋势, 说明火灾的发生可能与植被覆盖度的变化有关。这与中亚干旱区的其他炭屑记录相似, 表明中亚干旱区轨道尺度上的火灾可能主要受可燃生物量控制。暖湿/冷干的气候条件导致植被覆盖度扩张/缩小, 从而提供了更多/更少的可燃生物量, 使得火灾能够产生大量/少量炭屑。

     

New optically stimulated luminescence ages provide evidence of MIS3 and MIS2 eolian activity on Black Mesa, northeastern Arizona, USA

Eolian deposition on the semiarid southern Colorado Plateau has been attributed to episodic aridity during the Quaternary Period. However, OSL ages from three topographically controlled (e.g. falling) dunes on Black Mesa in northeastern Arizona indicate that eolian sediments there were deposited in deep tributary valleys as early as 35–30 ka, with most sand deposited before 20 ka. In contrast, the oldest OSL ages for sand sheets fall within the Pleistocene-Holocene climatic transition (~ 12–8 ka). Thus most eolian sediment accumulated on Black Mesa under climatic conditions that were in general cooler, moister, and more variable than today, not more arid, pointing to a considerable increase in sediment supply.     

A New Material of Lindera (Lauraceae) of the Late Pliocene from Tengchong, Yunnan and the Genus' Biogeography Significance

Lindera is a large genus of graceful, pleasantly scented and common native trees and shrubs of southern China and neighboring regions of SE Asia. There is a well-documented Cenozoic fossil record not only in these regions but also from elsewhere. A new fossil leaf record has been found in diatomite beds from the Upper Pliocene Mangbang Formation of Tuantian, Tengchong County, Yunnan. The leaves are identified and assigned to Lindera acuminatissima K. Q. Dao et B. N. Sun sp. nov., by comparing their leaf architecture and epidermal characteristics with those of 51 extant Lauraceae species and with 15 known fossil Lindera taxa. The specimens have well-preserved cuticles, with typical leaf architecture and epidermal characteristics of the Lauraceae, including entire leaf margin, intramarginal veins, basal ternate acrodromous primary veins, one-cell trichome base, paracytic stomatal apparatus, sunken guard cells, subsidiary hardly staining cells and presence of oil cells. These characteristics are consistent with Lindera sect. Daphnidium but are different from reported fossil and extant species of Lindera. The cuticles of Lindera are fragile and delicate with only three Lindera fossils reported based on this tissue. In terms of paleobiogeography, the fossil record indicates that Lindera is distributed in high- to mid-latitude regions of the Late Cretaceous to Paleocene northern hemisphere. Coincidentally, the records of Lindera located on both sides of the Bering Land Bridge possibly support the hypothesis that ancient plants extended via transcontinental exchanges through the Bering Corridor. In the Eocene, ancient Lindera spread to Europe through the Northern Degeer Route and the Southern Thulian Route. At the same time, ancient Lindera spread into Central Asia. Climatic changes and tectonization since the Neogene prevented the propagation of Lindera throughout Asia, North America and Europe, and hence the distribution areas have just regressed to the low-latitude regions in Asia and North America. From the Paleogene to the Neogene, Lindera has changed its distribution by surviving extreme climate changes. Quaternary glaciations ultimately led to Lindera becoming extinct in Europe. The new record from Tengchong, Yunnan, with its lower latitude located in tropical and subtropical regions, indicates that Lindera has lived in those regions since the late Pliocene.