Geology in the Falkland Islands

In the next few years we are likely to hear and learn much about the offshore geology of the Falkland Islands as exploratory drilling for hydrocarbons begins. The offshore geology may become better known than the onshore, of which there has been little detailed investigation in the 200+ years since settlements were established. Here we outline the history of geological investigations and present information gathered during recent fieldwork.     

Stone runs in the Falkland Islands

Large parts of the Falkland Islands are covered by conspicuous stone stripes. Their appearance is believed to be the result of partial vegetation cover developing on solifluction-transported rock.     

Carboniferous diamictite dykes in the Falkland Islands

Sedimentary dykes hosted in ? Ordovician-Devonian strata on the Falkland Islands contain diamictite. The dykes, which are discordant to the host rocks, are sub-vertical, parallel-sided sheets formed by downward injection of a semi-fluidized sediment. On West Falkland palynomorphs present in 2 of the 11 dykes located demonstrate a Late Visean-Early Namurian age. This is older than the main Lafonian Diamictite Formation (Permian) and indicates that the dykes are a rare preservation of sediments formed during the main ice coverage of the Gondwana glaciation. Vitrinite reflectance from organic matter in the dykes indicates a shallow burial history (< 2–3 km) for the southwest Falkland Islands implying deposition of an incomplete or condensed sequence during Late Palaeozoic times, although the stratigraphical relationship of the dykes indicates that this may be extended back into the Mid Palaeozoic. The two diamictite dykes located on East Falkland are shown to be younger; probably Permian in age.     

Circulating climate services: Commercializing science for climate change adaptation in Pacific Islands

In order to address the impacts of climate change, global multilateral institutions, development organizations, and national and regional science organizations are creating climate services – packages of useful climate information intended to help decision makers. This diffuse collection of actors and institutions suggest that producing climate services will help bridge gaps between climate scientists and decision-makers and will therefore help vulnerable countries and people manage the risks and optimize the impacts of climate change. This article examines this global science-policy ecosystem using the case of climate services produced by Australian science agencies for consumption in adaptation programming in the Pacific Island countries of Kiribati and Solomon Islands. Linking research on geographies of marketization and the neoliberalization of science, I demonstrate that within the climate service movement a focus on usefulness is paired with an emphasis on commercialization. As a result, this case shows the inherent tensions in the climate service model: first, a focus on competition and circulating service products at the expense of collaborative relationships; second, difficulties in negotiating uncertainty; and third contradictions between ‘objective’ and ‘entrepreneurial’ science. In each of these instances, the commercialized mechanisms through which climate services are governed, and the political economic circumstances within which they are produced, magnify rather than ameliorate gaps between science and policy.     

Late Pleistocene sediments and environmental change at Plaza Creek,Falkland Islands,South Atlantic

Late Pleistocene organic-rich sediments exposed in coastal bluffs near the head of Plaza Creek, East Falkland, have yielded conventional and AMS ¹⁴C dates of between 36 and 28 ka BP, and possess a pollen spectrum dominated by grasses, indicating a vegetation assemblage similar to that of the present day. Although some sample dates are anomalous and contamination by non-contemporaneous carbon cannot be ruled out entirely, the age estimates are consistent with evidence and dates from Antarctica, South America and the amphi-North Atlantic for climate shifts to interstadial conditions at around that time. The organic-rich units are developed in and enclosed by deposits attributed to processes of periglacial mass wasting. Grain-size characteristics suggest that these sediments may have been emplaced by solifluction, shallow translational landsliding and surface wash in at least five mass-wasting episodes. Some of the mass-wasting sediments might correlate with solifluction deposits above and below a podsolic soil dated to 26 ka BP at San Carlos, East Falkland, and with periods of cirque and valley glaciation identified in the uplands of the Falkland Islands. The similarity between late Pleistocene interstadial, Holocene and present-day pollen assemblages, and the lack of vegetation change within these periods, is characteristic of most cool temperate Southern Ocean islands, and may reflect the lack of sensitivity of the vegetation to climate change and/or a lack of climate variability for the time intervals covered. © 1998 John Wiley & Sons, Ltd.     

Human responses to Middle Holocene climate change on California's Channel Islands

High-resolution archaeological and paleoenvironmental records from California's Channel Islands provide a unique opportunity to examine potential relationships between climatically induced environmental changes and prehistoric human behavioral responses. Available climate records in western North America (7–3.8 ka) indicate a severe dry interval between 6.3 and 4.8 ka embedded within a generally warm and dry Middle Holocene. Very dry conditions in western North America between 6.3 and 4.8 ka correlate with cold to moderate sea-surface temperatures (SST) along the southern California Coast evident in Ocean Drilling Program (ODP) Core 893A/B (Santa Barbara Basin). An episode of inferred high marine productivity between 6.3 and 5.8 ka corresponds with the coldest estimated SSTs of the Middle Holocene, otherwise marked by warm/low productivity marine conditions (7.5–3.8 ka). The impact of this severe aridity on humans was different between the northern and southern Channel Islands, apparently related to degree of island isolation, size and productivity of islands relative to population, fresh water availability, and on-going social relationships between island and continental populations. Northern Channel Islanders seem to have been largely unaffected by this severe arid phase. In contrast, cultural changes on the southern Channel Islands were likely influenced by the climatically induced environmental changes. We suggest that productive marine conditions coupled with a dry terrestrial climate between 6.3 and 5.8 ka stimulated early village development and intensified fishing on the more remote southern islands. Contact with people on the adjacent southern California Coast increased during this time with increased participation in a down-the-line trade network extending into the western Great Basin and central Oregon. Genetic similarities between Middle Holocene burial populations on the southern Channel Islands and modern California Uto-Aztecan populations suggest Middle Holocene movement of people at this time from southern California desert environs westward to the southern islands, a migration perhaps stimulated by increased continental aridity.     

First lake record of Holocene climate and vegetation change of the Northern Kuril Islands

Investigation of Pernatoe Lake sediments in the south of Paramushir Island has enabled us to obtain the first continuous pollen record of climate and vegetation changes in the north of the Kurile archipelago during the Holocene. Series of radiocarbon datings of between 10 000 ± 40 and 2180 ± 40 years ago are evidence that the beginning of sediments accumulation, found after borehole development, is related to the Early Holocene. Diatom analysis has shown several stages in the lake development: raised bog on the border of the Pleistocene and Holocene, lagoon formation resulting from the sea level rise over 9–6 ky, and freshwater lake formation 6 ky and up to the present. Climate warming during the period attributed to the boreal and Atlantic periods of the Holocene is reflected by the dominance of Pinus pumila and Alnus serrulata assemblages in vegetation cover. Wide dune fields were formed in the Sea of Okhotsk and the Pacific shores of Paramushir Island 5–4 ky. Strengthening of atmogenic processes is related to cooling of the climate and drying of some areas of the underwater slope.     

论浙江北部早二叠世硅质岩层

长期以来对浙江北部早二叠世硅质岩层的划分与对比一直存在着分歧。在硅质岩层里发现了栖霞希瓦格动物群和一些有孔虫类化石。根据这些,浙北地区的早二叠世硅质岩层应归属栖霞组,相当于江苏宁镇地区的栖霞组上硅质岩段。     

Early Permian xiphosurid trackways from india

Present work is the first report of Early Permian xiphosurid trackways from India. Surface trackways and undertracks, preserved within ice-marginal storm-affected, shoreface sediments of the Talchir Formation, Jayanti coalbasin closely resemble Kouphichnium Nopsca 1923. Trackways reveal distinct heteropody with foliate pusher impressions, paired series of semi-circular, oval, V- or Y-shaped chilate (walking) leg impressions. Varied ventral impressions also include telson drag marks and telson dents; spine drag marks, book -gills impression, genal gouges as well as symmetric, paired lateral genal furrows, partial cubichnial impressions of prosoma and spinose opisthosoma. A tentative early Permian age (Asselian/Sakmarian) and marginal marine facies association points towards a paleolimuloidae affinity for the trace makers, which is in conformity with their inferred widths of exoskeleton, sub-rounded prosoma and subtriangular spinose opisthosoma with predictable movable spines. Flexed pusher impressions and co-dominant pincer impressions as well as, other ventral impressions in abundance, confirm crawling as their dominant mode of locomotion. Inferred presence of juvenile crawlers in the community suggests a probable shoreline or marginal marine ecospace.     

The pedigree and influence of fossil collections from the Falkland Islands: From Charles Darwin to continental drift

The Falkland Islands are typical of remote territories in that their early geological exploration was piecemeal and opportunistic. Whilst the resulting fossil collections (dominantly a Devonian fauna of the Malvinokaffric realm) remain the basis for modern interpretations, published accounts misrepresent their extent and provenance. Charles Darwin first discovered fossils during his 1833 visit aboard HMS Beagle, with subsequent British collections acquired in 1842 and 1876, respectively, by the Erebus and Terror and Challenger expeditions and in 1903 by the Scotia expedition. Darwin's collection, and much of the other material, is now held by The Natural History Museum, London (NHM) but some Darwin specimens were assimilated into other collections whilst at least one NHM ‘Darwin’ specimen was not collected by him. There may also be some uncertainty as to the origin of the Scotia collection, now held in Edinburgh by National Museums Scotland, in relation to a contemporary Swedish collection now held in Stockholm. The NHM holdings were supplemented by a number of enigmatic donations from private individuals and then by fossils collected during the first ‘official’ geological survey of the islands in 1920–1922. Meanwhile a large collection was built up in New York through collaboration in 1909 with a local collector – the Governor's wife! The regional associations of the fossils established the African heritage of Falklands geology, and thereby contributed to an understanding of continental drift as the mechanism for the fragmentation of the Gondwana supercontinent. The Falkland Islands are now regarded as a rotated microplate created during the break-up.     

江西乐平早二叠世地层

江西乐平早二叠世地层朱相水（江西师范大学地理系，江西南昌，３３００２７）关键词地层，早二叠世，栖霞期，乐平，江西实测剖面位于江西乐平沿沟煤矿矿区东隅，３ｋｍ无甲村附近，早Ｍ叠世地层发育于象鼻山与鲤鱼山之间。剖面系笔者与乐平矿务局沿沟煤矿的姚克敏、徐光...     

浙江舟山群岛首次发现二叠纪变质岩

浙江舟山群岛大衢岛及周边若干小岛出露少量变质岩系,包括斜长角闪岩、片麻岩、片岩、大理岩等,以往被归为陈蔡岩群。LAICP-MS锆石U-Pb测年结果表明,黑云斜长片麻岩变质新生锆石或岩浆锆石的变质边年龄在260~270Ma之间,大理岩的变质年龄为261.1±1.3Ma,侵入变质岩的未变形伟晶岩脉年龄为258.0±1.6Ma,表明该套变质岩系的变质时代约为260Ma,不能归入加里东期变质的陈蔡岩群。这是在华南东北缘地区首次发现二叠纪变质岩,为探讨华南东吴运动和全球海西运动,甚至泛大陆的重建提供了重要新信息。     

藏北申扎地区晚二叠世早期的皱纹珊瑚

作者在进行申扎县幅1∶25万区域地质调查工作中,发现一套巨厚的白云岩和白云质灰岩组成的岩系,整合覆于早二叠世中晚期地层下拉组之上,并在此岩系底部采集到晚二叠世早期的皱纹珊瑚Waagenophyllumindicumvar.crassiseptatumWu和LiangshanophyllumstreptoseptatumWang,从而确定本区有晚二叠世地层的存在。     

Early Holocene climate change and human occupation along the semiarid coast of north‐central Chile

The brief, terminal Pleistocene archaeological site at Santa Julia (SJ, 31° 50′ S; 71° 45′ W) is the only one with fluted projectile preforms and megafauna consumption known from the Chilean semiarid coastline. Here, we present the climatic history at SJ during the early Holocene reconstructed from pollen and charcoal analyses spanning 13.2–8.6 ka (=10³ calibrated ¹⁴C yr BP). Elevated charcoal concentrations confirm human activity by 13.2 ka. Human occupation decreased in intensity and charcoal practically disappears from the record after 10.6 ka, followed by wetland expansion at SJ between 10.5 and 9.5 ka. Local dominance of coastal shrubland reveals that dry phases occurred between >11.2–10.5 and 9.5–9.0 ka. Overall, these findings imply that by modulating available resources at both local and landscape levels climate change may have played an important role in explaining the peopling of semiarid coastal Chile. Copyright © 2010 John Wiley & Sons, Ltd.     

山东淄博地区早二叠世地层

<正> 山东淄博含煤盆地大地构造单元属泰山—沂山隆起的北缘,二叠纪地层发育,剖面完整,植物化石丰富。 1.淄博市博山区八陡镇东黑山山西组和下石盒子组剖面 剖面位于八陡镇北约500m处北大沟。 上覆地层 上石盒子组(P1/2)灰、灰绿、紫色等杂色泥岩     

白洋淀地区全新世以来的气候环境变化

白洋淀是华北平原最大的淡水湖泊,是研究全新世气候变化的理想区域。文章选择白洋淀东垒头剖面（厚382 cm）,在8个AMS-¹⁴C测年数据基础上,通过对其189个样品的地球化学元素、粒度和磁化率等指标分析,高分辨率地揭示了白洋淀地区全新世气候变化过程。研究结果显示：1）11335~10300 cal.a B.P.期间,CaO/MgO比值（多高于4.8）、（CaO+K₂O+Na₂O）/Al₂O₃比值（多高于1.3）、CaCO₃含量（多高于12%）和中值粒径（多高于15 μm）均为整个剖面最大值,干旱指数（平均约为0.019）为剖面次高值,CIA值（多低于45）、Ti含量（多低于0.38%）和低频磁化率值（多低于10×10^-8 m³/kg）为整个剖面的最低值,指示气候冷干,受新仙女木事件影响较大;2）10300~8500 cal.a B.P.期间,CaO/MgO比值、（CaO+K₂O+Na₂O）/Al₂O₃比值、干旱指数和中值粒径明显下降,CIA值、Ti含量、低频磁化率值均不同程度上升,指示气候向暖湿发展;3）8500~6000 cal.a B.P.期间,气候总体温暖湿润,干旱指数（平均达0.014）为剖面的最小值,CIA值和Ti含量较高,CaO/MgO比值、（CaO+K₂O+Na₂O）/Al₂O₃比值较低;但该阶段所有指标波动剧烈,8200 cal.a B.P.和6800 cal.a B.P.左右CaO/MgO比值、（CaO+K₂O+Na₂O）/Al₂O₃比值、干旱指数、CaCO₃含量出现高峰值,CIA值和Ti含量出现低峰值,指示2次明显冷干事件;4）6000~4200 cal.a B.P.期间,CaCO₃含量最低,但干旱指数较高,CaO/MgO比值、（CaO+K₂O+Na₂O）/Al₂O₃比值均有不同程度上升,指示气候湿润度有所下降;其中4500 cal.a B.P.为一次明显冷干事件,干旱指数呈现高峰值;5）4200~1035 cal.a B.P.期间,砂含量（多低于2%）、中值粒径（多低于10 μm）为剖面最小值;干旱指数、CaO/MgO比值、（CaO+K₂O+Na₂O）/Al₂O₃比值、CaCO₃含量明显升高,指示气候向着凉干方向发展;干旱指数在2800 cal.a B.P.呈现高峰值,指示一次明显冷干事件,同时,该时段受人类活动影响,低频磁化率值（多高于20×10^-8 m³/kg）明显高于其他时段。

     

Coastal megacities and climate change

Rapid urbanization is projected to produce 20 coastal megacities (population exceeding 8 million) by 2010. This is mainly a developing world phenomenon: in 1990, there were seven coastal megacities in Asia (excluding those in Japan) and two in South America, rising by 2010 to 12 in Asia (including Istanbul), three in South America and one in Africa.All coastal locations, including megacities, are at risk to the impacts of accelerated global sea-level rise and other coastal implications of climate change, such as changing storm frequency. Further, many of the coastal megacities are built on geologically young sedimentary strata that are prone to subsidence given excessive groundwater withdrawal. At least eight of the projected 20 coastal megacities have experienced a local orrelative rise in sea level which often greatly exceeds any likely global sea-level rise scenario for the next century.The implications of climate change for each coastal megacity vary significantly, so each city requires independent assessment. In contrast to historical precedent, a proactive perspective towards coastal hazards and changing levels of risk with time is recommended. Low-cost measures to maintain or increase future flexibility of response to climate change need to be identified and implemented as part of an integrated approach to coastal management.     

Expected impacts of climate change on extreme climate events

An overview of the expected change of climate extremes during this century due to greenhouse gases and aerosol anthropogenic emissions is presented. The most commonly used methodologies rely on the dynamical or statistical downscaling of climate projections, performed with coupled atmosphere–ocean general circulation models. Either of dynamical or of statistical type, downscaling methods present strengths and weaknesses, but neither their validation on present climate conditions, nor their potential ability to project the impact of climate change on extreme event statistics allows one to give a specific advantage to one of the two types. The results synthesized in the last IPCC report and more recent studies underline a convergence for a very likely increase in heat wave episodes over land surfaces, linked to the mean warming and the increase in temperature variability. In addition, the number of days of frost should decrease and the growing season length should increase. The projected increase in heavy precipitation events appears also as very likely over most areas and also seems linked to a change in the shape of the precipitation intensity distribution. The global trends for drought duration are less consistent between models and downscaling methodologies, due to their regional variability. The change of wind-related extremes is also regionally dependent, and associated to a poleward displacement of the midlatitude storm tracks. The specific study of extreme events over France reveals the high sensitivity of some statistics of climate extremes at the decadal time scale as a consequence of regional climate internal variability.     

Rapid sea level and climate change at the close of the Last Interglaciation (MIS 5e): evidence from the Bahama Islands

The geology of the Last Interglaciation (sensu stricto, marine isotope substage (MIS) 5e) in the Bahamas records the nature of sea level and climate change. After a period of quasi-stability for most of the interglaciation, during which reefs grew to +2.5 m, sea level rose rapidly at the end of the period, incising notches in older limestone. After brief stillstands at +6 and perhaps +8.5 m, sea level fell with apparent speed to the MIS 5d lowstand and much cooler climatic conditions. It was during this regression from the MIS 5e highstand that the North Atlantic suffered an oceanographic “reorganization” about 118±3 ka ago. During this same interval, massive dune-building greatly enlarged the Bahama Islands. Giant waves reshaped exposed lowlands into chevron-shaped beach ridges, ran up on older coastal ridges, and also broke off and threw megaboulders onto and over 20 m-high cliffs. The oolitic rocks recording these features yield concordant whole-rock amino acid ratios across the archipelago. Whether or not the Last Interglaciation serves as an appropriate analog for our “greenhouse” world, it nonetheless reveals the intricate details of climatic transitions between warm interglaciations and near glacial conditions.