The research front in Arctic Quaternary geology

Book reviewed in this article:
Andrews, J. T. (ed.) 1985. Quaternary Environments: Eastern Canadian Arctic, Baffin Bay and Western Greenland     

The Quaternary geology of the British Isles

This editorial accompanies the second of two sets of papers in the Proceedings (the first set appeared in Part 4 of 2009) that arise from the Annual Discussion Meeting of the Quaternary Research Association, co-hosted by the Royal Geographical Society. This collection represents two main categories of paper: on (1) on sand and gravel, several arising from projects funded from the British Government's Aggregates Levy, and (2) glaciation, with a degree of overlap between these. Both categories also include results of PhD research. The first category includes presentation of fluvially-based data from SW England, North Yorkshire, the Trent and the Fen Basin, as well as studies of raised beach deposits in southern England and County Durham. At the boundary between the categories is a paper on a pre-glacial fluvial valley system in the glaciated Dyfi basin, west Wales, and another on the marginal area between the Late Devensian Welsh ice cap and the contemporaneous Irish Sea ice stream, encompassing glacio-fluvial sands and gravels as well as fully glacigenic diamictons. There are also papers on the Woore Moraine, in Shropshire, and the glaciofluvial deposits of the Brampton kame belt, east of Carlisle, Cumbria. Studies at either end of Yorkshire include a paper on the sedimentology and luminescence dating of Glacial Lake Humber deposits, in the central Vale of York, and another that documents deglaciation and the emergence of the rivers in the watershed area between the rivers of this Vale (the Swale-Ure-Ouse system) and the Tees, to the north. The latter is followed up by a third paper on the palaeo-environmental evidence from the middle ‘piedmont’ reaches of these rivers. Two final papers fall outside of these categories. One documents periglacial activity during the Loch Lomond Stadial in south London, revealing significant complexity. The second reviews the engagement of the Quaternary community with the formal education system, with institutions, policy makers, planners and with the public at large, offering examples of good practice and setting out aspirations for continuation of such ‘outreach’ in the future.     

Quaternary geology in Sweden in the 1980s

The author gives a brief review of the most important research on Quaternary geology in Sweden during the last few years and the main lines of development of ideas. Emphasis is put on the present 'state of the art' within the following fields: Mapping, international projects, Quaternary deposits, dating methods, Pleistocene stratigraphy, glaciation models, deglaciation, sea-level changes, and Holocene.     

Flandrian pollen deposition rates and tree-line history in northern Fennoscandia

Previous absolute polien diagrams from northern Fennoscandia yielded evidence for a retreat of the pine limit from an earlier extended position to a position near the modern one between about 5000 and 3000 B.P. New absolute pollen data from the sediment core of Domsvatnet, a small tundra lake near the eastern coast of Varanger Peninsula, are used to demonstrate a parallel retreat in the birch limit. Areas outside the modern birch limit were colonized by early Flandrian pioneer birch woods between 9500 and 9000 B.P. and remained as birch woodland through middle Flandrian times until a retreat started around 5000 B.P. leading to the present tundra situation.
The Domsvatnet core shows anomalous high pollen deposition rates combined with relatively rapid matrix sedimentation, suggesting that pollen from outside the basin has been washed in with allochthonous material and concentrated in the sediment.     

Quaternary denudation of southern Fennoscandia – evidence from the marine realm

Throughout the last 1.1 million years repeated glaciations have modified the southern Fennoscandian landscape and the neighbouring continental shelf into their present form. The glacigenic erosion products derived from the Fennoscandian landmasses were transported to the northern North Sea and the SE Nordic Seas continental margin. The prominent sub‐marine Norwegian Channel trough, along the south coast of Norway, was the main transport route for the erosion products between 1.1 and 0.0 Ma. Most of these erosion products were deposited in the North Sea Fan, which reaches a maximum thickness of 1500 m and has nearly 40 000 km³ of sediments. About 90% of the North Sea Fan sediments have been deposited during the last 500 000 years, in a time period when fast‐moving ice streams occupied the Norwegian Channel during each glacial stage. Back‐stripping the sediment volumes in the northern North Sea and SE Nordic Seas sink areas, including the North Sea Fan, to their assumed Fennoscandian source area gives an average vertical erosion of 164 m for the 1.1–0.0 Ma time period. The average 1.1–0.0 Ma erosion rate in the Fennoscandian source area is estimated to be 0.15 mm a^?1. We suggest, however, that large variations in erosion rates have existed through time and that the most intense Fennoscandian landscape denudation occurred during the time period of repeated shelf edge ice advances, namely from Marine Isotope Stage 12 (c. 0.5 Ma) onwards.     

Hydrogeochemistry and sensitivity to acidification of streamwaters in crystalline areas of northern Fennoscandia

About 6,400 water samples were collected from small catchments in northern Finland and Norway above 66° N latitude as a part of the Nordkalott Project carried out jointly by the Geological Surveys of Finland, Norway, and Sweden. Electrical conductivity (EC) was measured in situ and Ca, Mg, Sr, Ba, Na, K, Si, Fe, Mn, Al, and Zn concentrations were determined from filtered and acidified samples by the ICAP method. The relative abundance of mafic, ultramafic, and carbonate rock components in the catchments is the most influential factor controlling the EC values and the main cation concentrations (Ca, Mg, Sr). These components also determine the HCO₃ alkalinity or acid-neutralizing capacity (ANC) of streamwater. In the northern coastal belt, Na is derived largely from airborne sea salts, but in the southwestern corner of the research area it may be derived partly from relict sea salts in sediments. The concentrations of Na, K, and Si do not depend solely on the lithological environment. Fe and, to a lesser extent, Mn and Al occur in the highest abundances in the low-lying, intensely paludified southern part of the area, suggesting that these metals tend to go into solution and are transported in complexed forms with dissolved and colloidic humic matter. The areal distribution patterns of the main cations (Ca, Mg, Sr) and of some heavy metals (Fe, Mn) in streamwater are fairly consistent with those of till and minerogenic stream sediments, although, in a statistical approach, only a few significant correlation coefficients were established.     

北京平原地区第四纪地质研究新进展

北京平原地处山前冲洪积扇分布区,区内湖泊密布,河流纵横,沉积环境多样。由于第四系三维结构的复杂性,对第四系进行地层划分有一定的难度。前人根据不同的资料对北京平原第四系进行过地层划分,建立了泥河湾组、周口店组、马兰组等多个岩石地层单位。这些地层单位主要是依据沉积凹陷钻孔岩心中的孢粉、有孔虫、介形虫等化石和少量的古地磁数据划分的,实际上仍是年代地层单位。由于这些地层单位划分依据不统一,识别标志不清晰,因此难以得到广泛的共识。近十余年来,随着资料的积累和对第四系三维结构的认识提高,特别是古地磁测年技术的普及,为北京平原第四纪地层的划分奠定了基础。本文依据40余个钻孔的古地磁测试数据,初步厘定了下更新统底界、中更新统底界、上更新统底界3个等时面。依据工程地质勘察、水文地质钻孔、考古发掘和泥炭调查等资料编绘了平原区全新统等厚度图。     

Late‐Quaternary palaeoclimatic research in Fennoscandia – A historical review

Birks, H. J. B. & Seppä, H. 2010: Late‐Quaternary palaeoclimatic research in Fennoscandia – A historical review. Boreas, Vol. 39, pp. 655–673. 10.1111/j.1502‐3885.2010.00160.x. ISSN 0300‐9483. Ideas and understanding of Late‐Quaternary climatic history, especially in the Lateglacial and the postglacial, were initiated in Fennoscandia in the 19th century with pioneering studies on peat stratigraphy, megafossils and macrofossils. This review traces the history of palaeoclimatic research and the development of current ideas about climatic changes, with particular reference to the Lateglacial and its rapid climatic fluctuations, such as the Younger Dryas period, and to the Holocene, with its thermal maximum and shifts in precipitation.     

Quaternary stratigraphy in the northern North Sea

Core recovered from IGS Borehole 78/9 is described and suhsamples have been examined for geotechnical properties, palaeomagnelic events and microfauna content. It was hoped that this approach would provide a Quaternary stratigraphy for the area by assuming that significant geological events correlate with simultaneous changes in the lithology, gcotechnical properties, geomagnetic polarity and climatic regime. The magnetic reversals observed were linked to the existing palaeomagnelic time scale and stratigraphic ages assigned to the various units obtained on a 'best fit' to this time scale. The stratigraphic succession and geological history deduced for the borehole are compatible with other borehole and vibrocore data available from the area.     

羌塘盆地石油地质条件与初步评价

羌塘盆地是我国西部尚待进一步勘探与开发的最具前景的中、新生代大型含油气盆地。盆地内发育有10套烃源层，其中主要烃源层有4套，即上侏罗统索瓦组(J3s)、夏里组(J2x)、布曲组(J2b)和上三叠统肖茶卡组(T3x)，除中央隆起带西部缺失外，在盆地其他地区有广泛分布，累积厚度大于3000m。主要烃源层由碳酸盐岩和泥质岩两类岩性组成，J3s和T3x主要为碳酸盐岩烃源层，有机质含量普遍不高，有机碳含量为0．15％。0．25％，多属差-中等烃源岩。J3x和T3x主要是泥质岩烃源层，有机质含量较高，有机碳含量为0．6％。1．2％，属中等—好轻源层。此外，J2x和J3s还有一套油页岩烃源层，不仅有机碳含量特别高，而且可溶有机质也特别丰富，是盆地内最有价值的烃源层。4套主要烃源层均为海相沉积，有机物质以海相低等生物为主，形成以混合型(Ⅱ型)为主的有机质类型，具有较强的成烃能力。盆地中间有机质热演化处于成熟阶段，盆地周边和中央隆起带附近处于高成熟阶段，再向外达到了过成熟阶段。推测，盆地中部为原油分布区，向外扩展为凝析油—湿气区，再向外为干气分布区。其中以索瓦组的原油分布范围最大，而自夏里组→布曲组→肖茶卡组，原油分布区的面积逐步缩小。盆地储集岩类有碎屑岩和碳酸盐岩以及少量火山岩。碎屑岩主要分布于上三置统肖茶卡组三段、中侏罗统雀莫惜组(J2q)、上株罗统夏里组和雪山组(J3x)及古近系双湖组(E2s)；岩石类型以细砂岩、粉砂岩为主，次为中砂岩和组砂岩。碳酸盐岩储层主要分布于肖茶卡组一、二段，布曲组和索瓦组；主要岩石类型有泥灰岩、粒屑灰岩、鲕粒灰岩、生物礁灰岩和白云岩等，其中白云岩储层具有特殊的意义。火山岩分布于二叠系和上三叠统。盆地内白云岩储层分布较广，在乎面上分布与古隆起有关，已发现的白云岩中，以隆鄂尼布曲组的白云岩规模最大，并部分地区储有轻质原油。盆地内存在多层盖层岩石类型，主要有泥质岩、蒸发岩、碳酸盐岩、致密砂岩、火山岩、硅质岩和煤岩等，其中肋三种分布广泛，各层系均较发育，且封闭性能较好，是盆地内主要的益层岩石类型，尤以泥质岩和蒸发岩更为重要。羌塘盆地具备了形成大、中型油气田的石油地质条件，是青藏地区最具油气希望的盆地，展现了美好的勘探前景和开发潜力。     

Spring temperature variability in northern Fennoscandia AD 1693–2011

A reconstruction of spring (April–May) temperature for northern Fennoscandia developed from the Tornionjoki (Tornio river) long cryophenological record of ice break‐up dates, back to AD 1693, is presented. The record is strongly climatically sensitive and explains 67% of the variance in the instrumental data over the last 150 years. The record exhibits a stepped decrease in the duration of the river's ice cover by 14 days, equivalent to an increase in April–May mean temperature of approximately 2.5°C over the last three centuries. The relationship between the date of ice break‐up, and accumulated daily mean temperatures (>0°C) is investigated. Uncertainty in the observation of ice break‐up is also considered in addition to the potential of this time series for regional climate model validation. Copyright © 2011 John Wiley & Sons, Ltd.     

The lithosphere-asthenosphere system in Fennoscandia

We present a summary of the available information on Rayleigh-wave dispersion data for the Fennoscandian region. The observations have been combined to produce regional dispersion relations which have then been subjected to the “hedgehog” inversion procedure. The results are presented on a map outlining the thickness of the lid and the shear velocities in both the lid and the asthenosphere channel. Lid thickness up to around 135 km is found in the Bothnia-north-central Finland area with, if any, weak shear velocity contrast to the underlying layer. The surrounding areas are characterized by lid thickness up to around 75 km; a stronger low-velocity zone to lid contrast may be found in the Caledonian and Baltic Sea area (0.25÷0.45 km/s). Taking into account Moho depth data and the aforementioned results, a map of the lithosphere-asthenosphere system was derived.     

Magnetic fabric and emplacement of the post-collisional Pomovaara Granite Complex in northern Fennoscandia

The Proterozoic Pomovaara Granite Complex in northern Finland comprises three separate highly magnetic granite stocks. They are discordant, apparently unfoliated and according to isotope data, a significant Archaean component characterizes the source of these granites. The three stocks are aligned in an array parallel to major trans-crustal faults as interpreted from both aeromagnetic and gravity data. Their younger age of 1.8 Ga, compared to the main tectonic events at 1.9 Ga in northern Fennoscandia, indicates their post-collisional nature with respect to these events. The anisotropy of magnetic susceptibility (AMS) was studied together with magnetic, gravity and geological data in order to assess the emplacement mechanisms of the Pomovaara Granite Complex, and the possible tectonic control of fault systems on the ascent and emplacement of granitic magma. The orientation of magnetic fabrics within the granite stocks indicates that the direction of the original magma upwelling was from the SW, parallel to the major fault zones that controlled, at the crustal scale, the ascent of granite magmas. The predominant NW–SE orientations of the minimum magnetic axes of the magnetic ellipsoid and the elongate shapes of the stocks indicate compression normal to the deep fault trend during the crystallization of the granite magma.     

The importance of applied Quaternary geology for planning of land use and natural resources

Book reviewed in this article:
De Mulder, F. J. & Hageman, B. P. (eds.) 1989: Applied Quaternary Research