Cover Rocks Research Articles

The effects of plate margin inhomogeneity on the deformation pattern within west-Central Zagros Fold-and-Thrust Belt

Zagros Folded and thrust Belt (ZFTB) is a Cenozoic mountain belt in SSW of Iran and northeast of Arabia that resulted from closure of Neo-Tethys and collision between Arabia passive margin and Central Iran active margin. At this tectonic grain of Alp-Himalayan chain, change of the tectonic regime, degree of basement involvement, and character of accommodation of the deformation, in time and space, has been under debate. The results show that the deformation along the Zagros is not uniformly accommodated. Although the researchers have already paid attention to basement involvement in addition to the sedimentary cover rocks, little has been shown on the role of the basement's rigidity and lower crust's rheology on the deformation pattern along and across the belt. This study tries to address these questions in terms of inversion of slip vector of basement earthquakes, measurement of fault-slip data on the cover rocks, geomorphic and field observations, and existing geodetic and gravity data, with especial focus on Dezful embayment and surrounding area. The results show the Dezful embayment plays an indenter role. It, with the other reentrants, changes the obliquity of Arabian plate convergence, facilitates the escape of the upper crust toward free mechanical boundaries in salients, controls the slip-rate of Zagros Main Recent Fault at the rear of the belt and contributes in forming Zagros Fold-and-Thrust Belt as an orocline. The viscous lower crust helps the strain partitioning by providing a ductile shear base under the rigid upper crust.

Provenance and paleogeography of the Devonian Durazno Group, southern Parana Basin in Uruguay

A succession of Devonian cover rocks occurs in outcrop and in the subsurface of central-northern Uruguay where they were deposited in an intracratonic basin. This Durazno Group comprises three distinct stratigraphic units, namely the Cerrezuelo, Cordobés and La Paloma formations. The Durazno Group does not exceed 300 m of average thickness and preserves a transgressive-regressive cycle within a shallow-marine siliciclastic shelf platform, and is characterized by an assemblage of invertebrate fossils of Malvinokaffric affinity especially within the Lower Devonian Cordobés shales. The sedimentary provenance of the Durazno Group was determined using petrography, geochemistry, and morphological studies of detrital zircons as well as their U–Pb ages. Sandstone petrography of Cerrezuelo and La Paloma sequences shows that they have a dominantly quartz-feldspathic composition with a minor contribution of other minerals. Whole-rock geochemical data indicate that alteration was strong in each of the three formations studied; chondritic-normalized REE patterns essentially parallel to PAAS, the presence of a negative Eu-anomaly, and Th/Sc and La/Hf ratios point to an average source composition similar to UCC or slightly more felsic. Within the Cerrezuelo Formation, recycling of older volcano-metasedimentary sources is interpreted from Zr/Sc ratios and high Hf, Zr, and REE concentrations. U–Pb detrital zircon age populations of the Cerrezuelo and La Paloma formations indicate that the principal source terranes are of Neoproterozoic age, but include also minor populations derived from Mesoproterozoic and Archean-Paleoproterozoic rocks. A provenance from the Cuchilla Dionisio-Dom Feliciano, Nico Pérez and Piedra Alta terranes of Uruguay and southern Brazil is likely. This study establishes an intracratonic extensional tectonic setting during Durazno time. Considering provenance age sources, regional paleocurrent distributions and the established orogenic history recorded in SW Gondwana, we suggest that the basin fill was derived from paleohighs located in what is currently SE Uruguay.

It’s not all about the creeks: protection of multiple habitats will improve biodiversity conservation in a eucalypt forest

Understanding patterns in the distribution and abundance of wildlife across the landscape can aid in identifying the relative importance of habitats for biodiversity conservation. We aimed to identify whether riparian habitats were more important than other areas in the landscape to small terrestrial vertebrates. The study site was surveyed using 450 pit traps distributed across riparian, midslope and ridge top habitat. Riparian sites had the greatest abundance of small vertebrates of the three habitats. During some months of the year, there was a significant difference in the composition of the faunal assemblage between habitats. Unsurprisingly, riparian habitats were particularly important for frog species and it was these species that accounted for the greater abundance in this habitat. Riparian habitat was less important for other taxonomic groups and the more floristically rich midslope and ridge habitats, which had a greater abundance of leaf litter, fallen logs and rock cover, were favoured by mammal and reptile species. The conservation of riparian sites, without the protection of other habitats, overlooks a substantial proportion of the biodiversity in the landscape. This study may help inform management decisions in the Upper Warren region and other similar forested landscapes, regarding the location and timing of fauna monitoring and the frequency of fuel reduction burns.

Glacial sediment and landform record offshore NW Scotland: a fjord–shelf–slope transect through a Late Quaternary mid-latitude ice-stream system

Current estimates of ice-mass loss from ice sheets vary, but there is consensus that the rate of loss has increased over the last two decades from c. 100 to c. 400 Gt a−1 with the great majority occurring within ice-stream systems (e.g. Shepherd et al. 2012; Hanna et al. 2013). Where ice streams terminate in open-marine settings large volumes of ice are discharged into the oceans via calving, as currently seen in Pine Island Bay, West Antarctica or at Jakobshavn Isbrae, West Greenland. At the Last Glacial Maximum (LGM), an ice sheet covered more than two-thirds of the British Isles (50–61° N) and reached onto the continental shelf, in places extending to the shelf edge in the west (Gibbard & Clark 2011; Clark et al. 2012). In this contribution we summarize the Pleistocene sediment and landform record of a large mid-latitude ice stream that once drained the NW sector of the British–Irish Ice Sheet (BIIS). Drawing on marine geophysical and geological data from the NW UK continental shelf collected over four decades, we describe the main elements of the system along a transect stretching for >300 km from the heads of the fjords to beyond the shelf slope. The work draws largely on previously published research (Stoker et al. 1993, 2006, 2009, 2010; Stoker & Bradwell 2005; Bradwell et al. 2007, 2008 a , b ; Bradwell & Stoker 2015 a , b ), but includes some new insights and interpretations. The bedrock geology of NW Scotland and the Hebrides Shelf is structurally complex and lithologically diverse. Unsurprisingly, the geological structure imposes a general first-order control on the topography of the region with resistant upstanding Precambrian rocks typically forming the extant landmasses and bathymetric highs, and the weaker Mesozoic cover rocks flooring …

Construction of Dry Cover System for Prevention of Acid Mine Drainage at Mine Waste Dump in Open Cast Coal Mines, Indonesia

Acid Mine Drainage (AMD) which occurs when sulfide minerals are exposed to water and oxygen with an excavation is one of the serious environmental problems in the world. A dry cover system is generally constructed in waste dump for the prevention of AMD in Indonesia by virtue of low cost and availability of waste rocks for a cover layer. However, the failure of the system caused by the lack of information related to the construction of cover system in mines, which leads to AMD, has been reported recently in Indonesia. In this study, the field investigation was conducted in pit and waste dump in open cast coal mine in Indonesia with the aim of obtaining the information on the construction of a cover layer and backfilling conditions of waste rocks in the waste dump. The rock samples taken in two areas of the mine were analyzed by geochemical analysis and sequential extraction with acids. The results indicated that Net Acid Producing Potential (NAPP) of the rocks in the waste dump down to 100 cm depth in both areas was from 10 to 30 kg H2SO4/ton, suggesting that Potentially Acid Forming (PAF) was backfilled in a cover layer. The backfill of PAF was contrary to the concept of cover system, which caused the failure of constructing a cover layer. The cause of the failure was likely attributed to the shortage of cover rocks which are classified as Non Acid Forming (NAF) or the failure of proper placement of them by an operational problem in the areas. Moreover, the results of the extraction with acids suggested that the form of iron and sulfur has to be taken into account to discuss the occurrence of AMD.

喀斯特天然林植物多样性指数和土壤理化指标的相关性

PDF HTML阅读 XML下载 导出引用 引用提醒 喀斯特天然林植物多样性指数和土壤理化指标的相关性 DOI: 10.5846/stxb201403220514 作者: 作者单位: 贵州省林业科学研究院,贵州省林业科学研究院;贵州大学,贵州省林业科学研究院,贵州大学;贵州省林业科学研究院,贵州省林业科学研究院,贵州省林业科学研究院,贵州省林业科学研究院,贵州省林业科学研究院,贵州大学;贵州省林业科学研究院 作者简介: 通讯作者: 中图分类号: 基金项目: 林业公益性行业科研专项(201104002);贵州省科技厅项目(黔省专合字TZJF2008-17,2009-2083,2008-73,黔科合字2007-1021,2010-05) Correlation on plant diversity indices and soil physical and chemical indicators of karst natural forest, Southern Guizhou Province, China Author: Affiliation: Guizhou Provincial Academy of Forestry,,,,,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:植物多样性的土壤生态系统功能是喀斯特生态学研究的热点之一。在贵州省茂兰国家级自然保护区不同功能区(干扰等级)内采用野外样地调查和实验室分析相结合的方法,分析了41个喀斯特森林样地的植物多样性指数和土壤理化指标值的变化规律与相关性。结果表明:(1)依据乔木层物种重要值聚类法划分的5个喀斯特森林类型包括小叶栾树-青冈栎林、香叶树-枫香林、香椿-香叶树林、灯台-小花梾木林和檵木-马尾松林,由核心区、缓冲区、实验区至外缘区,乔木层植物多样性指数、林地岩石裸露率、土壤蓄水量、肥力及养分指标呈降低趋势。(2)因子分析表明不同层片植物多样性和不同土层土壤理化因子的相关趋势性各异。相关显著的因子对数量率呈乔木 > 灌木 > 草本的趋势,乔木植物多样性因子起主导作用。(3)喀斯特森林乔木层植物多样性指数和土壤理化指标的相关性分3种类型。直线型是植物多样性指数和土壤理化指标值相关性中较普遍的一类,相应指标对数量率为39.84%;曲线型是植物多样性指数和土壤理化指标值相关性中机理较复杂的一类,相应指标对数量率为46.10%,其中植物多样性指数有拐点值无生态意义的指标对数量率为11.72%,有拐点值有生态意义且呈先降后升、或先升后降趋势的指标对数量率分别为17.19%;无关型是植物多样性指数和土壤理化指标值相关性不显著,相应指标对数量率为54.69%。(4)喀斯特地区水土资源管理为目标的营林措施中,天然林乔木层植物多样性指数对土壤物理、肥力和养分指标响应的拐点值可成为人工造林中物种数量与株数比例选择的参考依据之一。 Abstract:Soil ecosystem function and plant diversity is receiving much attention in karst ecological studies. Changes and correlation laws in plant diversity indices and soil physical and chemical indicators of 41 karst forest plots were analyzed on different functional areas in the Maolan National Nature Reserve of southern Guizhou Province, China. This research adopted the combination method of wild field plot investigation and laboratory analysis. Results show:(1) The importance values of the arbor species clustering method resulted in five karst forest types:Koelreuteria minor-Cyclobalanopsis glauca forest, Lindera communis-Liquidambar formosana forest, Toona sinensis-Lindera communis forest, Cornus controversa-Cornus parviflora forest and Loropetalum chinense-Pinus massoniana forest. The arbor plant diversity indices, bare rock coverage, soil water storage indicators, soil fertility indicators and nutrient indicators showed a decreasing trend from the core area, to the buffer area, to the experimental area and to the outer area. The Margalef index, Simpson index, Shannon-Wiener index and Pielou index of the arbor and herb layer species showed a significant difference between some forest types. However, the diversity indices differences of the shrub layer were not significant. Significant differences of some indicators between the different forest types confirmed the influence of human disturbance to the karst forest in the natural recovery process. (2) Factor analysis revealed different correlation trends between the plant diversity factors of different layers, and the physical and chemical factors of different soil horizons. The analysis conformed to the general regularity of plant growth in the development of the arbor, shrub and herb layer and the co-evolution between the vegetation and soil system of karst forest in the natural recovery process. The number rate of significant factor-pairs of the soil physical and chemical indicators related to the arbor, shrub and herb plant diversity indices were 36.38%, 27.27% and 18.19%, respectively. The arbor plant diversity factor had the strongest relationship with the soil physical and chemical indicators. (3) The significant correlations between the arbor plant diversity indices and the soil physical and chemical indicators were divided into three types:i) Linear correlation is a general relationship between the plant diversity indices and soil physical and chemical indicators; 39.84% of the indicator-pairs were in this category, where the plant diversity indices increased to raise or lower the soil physical and chemical indicators accordingly. ii) Curve correlation is a complex relationship between the plant diversity indices and soil physical and chemical indicators; 46.10% of indicator-pairs are accounted for in this way. Inflection point values of the plant diversity indices without ecological meaning accounted for 11.72% where the relationship could be explained using straight lines or other models. The ecological inflection points of the plant diversity indices, which periodically impacted on soil physical and chemical indicators between the upwards and downwards trends of the quadratic curves, accounted for 17.19% of the indicator-pairs. The values of these plant diversity indices can be adjusted on the basis of the soil management goal in forest planting. iii) No significant correlation means the plant diversity indices are independent of the soil physical and chemical indicators, and planting measures for plant diversity indices cannot effectively change the soil physical and chemical indicators; 54.69% of indicator-pairs corresponded to this model. The different response modes aid the interpretation of ecosystem function through the plant diversity hypothesis. (4) Inflection points are the top values of the upwards and downwards trends in the quadratic curve response of arbor plant diversity indices to soil physical and chemical indicators. They are in index values of Margalef for 0.71-2.70 and 4.80-9.70, Simpson for 0.57-0.66 and 0.72-0.86, Pielou for 0.50-0.76 and 0.83-0.95 and Shannon-Wiener for 1.35-1.43 and 2.57-3.47, respectively. These values are used for one of the selection references of species and number proportions in artificial forestation. 参考文献 相似文献 引证文献

계면요소를 이용한 지반-라이닝 상호작용 모델에 의한 터널 콘크리트 라이닝 연구

NATM터널의 콘크리트 라이닝에 작용하는 지반하중을 산정하는 방법으로 수치해석적 기법인 지반-라이닝 상호작용모델(Ground-Lining Interaction Model, GLI 모델)에 의한 지반하중 산정방법이 제안되었다. 그러나, 기존의 GLI 모델은 지반과 지보재 또는 콘크리트 라이닝 사이에 존재하는 계면(Interface)의 구조적 역할을 반영하지 못하였다. 이에 본 연구에서는 기존의 GLI 모델에 계면요소를 반영하여 보다 실제에 가까운 모델로 구현하였다. 그리고, 지반조건 및 토피별 지반하중을 수치해석을 통해 산정하고 기존의 GLI모델 지반하중 상관식을 수정하여 제안하였다. 연구결과, 기존 모델에 비해 계면요소 반영시 지반하중은 토피두께에 따라 IV등급 지반조건에서는 평균 88~106%, 풍화토 지반조건에서는 평균 47~57% 수준으로 감소하였다. 본 연구결과로 콘크리트 라이닝에 작용하는 지반하중을 실제에 가까운 모델로 산정할 수 있으며, 상관식을 이용하여 일관되고 경제적인 설계가 가능하게 될 것으로 예상된다. In NATM tunnel, the Ground-Lining Interaction model(GLI model) had been proposed a one of the numerical analysis as the ground load estimation method of the concrete lining. But this model was not applied with the interface mechanism between the ground and the support member or concrete lining. Therefor in this study, it is implemented as a model for closer than actual states that the interface element applied to the existing GLI model. And the modified GLI formula is proposed with the ground load estimation that is from the numerical results for each ground and rock cover conditions. Based on the numerical results, the ground load acting on concrete lining is reduced to ave. 88~106% in case of IV ground condition and ave. 47~57% in case of weathered soil condition comparing with the existing GLI model. It can be anticipated that the results obtained from this study can be applied to an estimation of the ground load on the concrete lining modeled like as real states, consistent and economical design.

OKYANUS ORTASI SIRTLARDA OLUŞAN MASİF SÜLFİD YATAKLARININ SIRLARI VE KÜRE- MAĞARADORUK BAKIR YATAĞI

Kure region is located in western part of the Pontide tectonic belt. The oldest rocks around Kure are Paleozoic metamorphic rocks constituting “Rhodope-Pontide” continent. Liassic-pre Liassic ophiolites and basaltic volcanics, which form Paleotethys Ocean Floor are situated on “Rhodope-Pontide” continent as Paleotethys Ocean Floor residuals. Massive sulfide deposits in Kure Region are closely associated with pre Liassic – Liassic basaltic volcanics and intercalating black shale. These deposits are considered to have formed during hydrothermal mineralization processes when basaltic volcanism had stopped and defined as “Black Smoker” today. Massive sulfide bodies in Magaradoruk copper deposits are lens shaped. Although ore lenses take place sometimes in basalts and black shales, they are generally located on basalts and are covered by black shales. In Kure region, fold structures are intensely observed, and Magaradoruk deposit is located on western flank of an overturned anticline. Magaradoruk deposit is formed by several small and a big ore body and by less developed, underlying stockwork disseminated ore. The big ore body is 600 m long, 250 m wide and nearly 40 m thick. As main ore minerals; pyrite and chalcopyrite are observed. In few amounts; marcasite, magnetite, hematite, sphalerite, covelline, neo-digenite, malachite, azurite, fahlers are seen. In fewer amounts; bravoite, lineiite (karolite), limonite, and in trace amounts; chromite, rutile anatase, chalcosine, cuprite, tenorite, pyrrhotite, valleriite, bornite, galenite, native copper and native gold are observed. Main gangue minerals are; quartz, siderite-ankerite calcite, dolomite and chlorite. Magaradoruk massive sulfide deposit within basaltic rocks resembles to Siirt Madenkoy, Ergani massive sulfide deposits, to “Cyprus” type massive sulfide deposits and modern Cyprus type massive sulfide deposits in terms of mineral contents; and to Ergani Mihrapdagi, Papuke, Pakotai and Parakoa deposits in terms of cover rocks, which are Cyprus type massive sulfide deposits, in New Zealand

The detrital record of late‐Miocene to Pliocene surface uplift and exhumation of the Venezuelan Andes in the Maracaibo and Barinas foreland basins

AbstractA multidisciplinary approach, combining sediment petrographic, palynological and thermochronological techniques, has been used to study the Miocene‐Pliocene sedimentary record of the evolution of the Venezuelan Andes. Samples from the Maracaibo (pro‐wedge) and Barinas (retro‐wedge) foreland basins, proximal to this doubly vergent mountain belt, indicate that fluvial and alluvial‐fan sediments of similar composition were shed to both sides of the Venezuelan Andes. Granitic and gneissic detritus was derived from the core of the mountain belt, whereas sedimentary cover rocks and uplifted foreland basin sediments were recycled from its flanks. Palynological evidence from the Maracaibo and Barinas basins constrains depositional ages of the studied sections from late Miocene to Pliocene. The pollen assemblages from the Maracaibo Basin are indicative of mountain vegetation, implying surface elevations of up to 3500–4000 m in the Venezuelan Andes at this time. Detrital apatite fission‐track (AFT) data were obtained from both stratigraphic sections. In samples from the Maracaibo basin, the youngest AFT grain‐age population has relatively static minimum ages of 5 ± 2 Ma, whereas for the Barinas basin samples AFT minimum ages are 7 ± 2 Ma. With exception of two samples collected from the Eocene Pagüey Formation and from the very base of the Miocene Parángula Formation, no evidence for resetting and track annealing in apatite due to burial heating in the basins was found. This is supported by rock‐eval analyses on organic matter and thermal modelling results. Therefore, for all other samples the detrital AFT ages reflect source area cooling and impose minimum age constraints on sediment deposition. The main phase of surface uplift, topography and relief generation, and erosional exhumation in the Venezuelan Andes occurred during the late Miocene to Pliocene. The Neogene evolution of the Venezuelan Andes bears certain similarities with the evolution of the Eastern Cordillera in Colombia, although they are not driven by exactly the same underlying geodynamic processes. The progressive development of the two mountain belts is seen in the context of collision of the Panama arc with northwestern South America and the closure of the Panama seaway in Miocene times, as well as contemporaneous movement of the Caribbean plate to the east and clock‐wise rotation of the Maracaibo block.

Detrital-zircon geochronology and provenance of the Ocloyic synorogenic clastic wedge, and Ordovician accretion of the Argentine Precordillera terrane

The Precordillera terrane in northwestern Argentina is interpreted to be an exotic (Laurentian) continental fragment that was accreted to western Gondwana during the Ordovician. One prominent manifestation of the subduction and collision process is a Middle–Upper Ordovician clastic wedge, which overlies a passive-margin carbonate-platform succession in the Precordillera. U/Pb ages of detrital zircons from sandstones within the clastic wedge, as well as zircons from clasts within conglomerates, provide documentation for the composition of the sediment provenance. The ages of detrital zircons are consistent vertically through the succession, as well as laterally along and across strike of the Precordillera, indicating a single, persistent sediment source throughout deposition of the clastic wedge. The dominant mode (∼1350–1000 Ma) of the detrital-zircon ages corresponds to the ages of basement rocks in the Western Sierras Pampeanas along the eastern side of the Precordillera. A secondary mode (1500–1350 Ma) corresponds in age to the Granite-Rhyolite province of Laurentia, an age range which is not known in ages of basement rocks of the Western Sierras Pampeanas; however, detritus from Granite-Rhyolite-age rocks in the basement of the Precordillera was available through recycling of synrift and passive-margin cover strata. Igneous clasts in the conglomerates have ages (647–614 Ma) that correspond to the ages of minor synrift igneous rocks in the nearby basement massifs; the same ages are represented in a minor mode (∼750–570 Ma) of detrital-zircon ages. A quartzite clast in a conglomerate, as well as parts of the population of detrital zircons, indicates the importance of a source in the metasedimentary cover of the leading edge of the Precordillera. The Famatina continental-margin magmatic arc reflects pre-collision subduction of Precordillera lithosphere beneath the western Gondwana margin; however, no detrital zircons have ages that correspond to Famatina arc magmatism, indicating that sedimentary detritus from the arc may have been trapped in a forearc basin and did not reach the foreland. The indicators of sedimentary provenance for the foreland deposits are consistent with subduction of the Precordillera beneath western Gondwana, imbrication of basement rocks from either the Precordillera or Gondwana into an accretionary complex, and recycling of deformed Precordillera cover rocks.

Effects of Special Protection Area Designation on Soil Properties and Vegetation Coverage of Degraded Trails

This study was conducted to evaluate how the special protection area designations of degraded trails effect on the soil and vegetation recovery of degraded trails. The study areas were established on an opened trail and a 16-year closed trail, which was prohibited to enter after the designation as a special protection area for recovery, at Bukhansan National Park. Soil core sampling and measurements of vegetation cover were performed to compare soil and vegetation properties of the trails. Soil bulk density increased and soil water total nitrogen decreased on the opened trail, while no significant differences were found on bulk density, soil water, total nitrogen, acidity, and organic matter on the closed trail. On the opened trail, vegetation cover was seemed to be degraded, because vegetation litter cover ratio was low and barren rock cover ratio was high. On the closed trail, litter rock barren cover ratio of the closed trail was recovered, but only limited recovery was found on vegetation cover by applying environmental damage condition rating class. In conclusion, the closed trail was recovered by designation of special protection area, while difference in recovery progress of soil and vegetation was found. Therefore, designation of special protection area of degraded area should be based on scientific basis of recovery characteristics of the area. In order to improve the effectiveness of special protection area system, further specific standards for special protection area designation and management would be needed, considering ecological and social importance of target areas.

Beating the blaze: Fire survival in the fan aloe (Kumara plicatilis), a succulent monocotyledonous tree endemic to the Cape fynbos, South Africa

AbstractFire is central to the ecology of Mediterranean‐type climate ecosystems, but little is known about the fire ecology of succulent plants therein. This study investigated the fire ecology of an arborescent succulent monocot, Kumara plicatilis (L.) G. D. Rowley (Asphodelaceae), a Cape fynbos endemic. Habitat suitability was assessed to determine whether the species tolerates or ‘avoids’ fire, and fire survival traits (bark thickness and tissue water content) were measured. The population size structure and density of three K. plicatilis populations were assessed after natural fires, and resprouting potential was investigated. Kumara plicatilis adopts a dual fire survival strategy, occupying rocky sites to ‘avoid’ fire and possessing morphological features that afford fire tolerance, e.g. well‐protected apical meristems and thick corky bark. Bark thickness of burned individuals in situ was similar to unburned plants, suggesting that K. plicatilis bark provides effective insulation against fire. Mortality rates were 64%, 40% and 11%, and decreased as rock cover at the population level increased. All three populations showed reduced plant density post‐fire, with greater density reductions associated with lower rock cover. Small plants appear most vulnerable to fire damage due to lower absolute bark thickness and plant heights within the flame zone. Kumara plicatilis is an apical sprouter, recovering after fire or mechanical stem damage by onward growth from surviving stem apices, rather than resprouting. Post‐fire population recovery therefore likely depends on inter‐fire recruitment.

Phanerozoic denudation across the Kola Peninsula, Northwest Russia: implications for long-term stability of Precambrian shield margins

Contrasting views exist on the stability of the Earth’s shield regions over the last 1 Ga that have major implications for reconstructing erosion patterns on shields and the supply of sediment to intra-cratonic and marginal basins. This paper explores Phanerozoic denudation rates and patterns on the northern part of the Fennoscandian Shield in the Kola Peninsula, Northwest Russia. This shield region was intruded by magmatic rocks of the Kola Alkaline Province (KAP) in the Devonian and Early Carboniferous. The KAP comprises a varied suite of alkali–ultramafic plutonic and hypabyssal intrusions, diatremes and dykes that was emplaced at various depths in the crust and allows assessment of depths and rates of erosion during and since the KAP magmatic episode. Further evidence of long-term denudation is provided by Mesoproterozoic and Neoproterozoic cover rocks found around the margins of the Kola Peninsula and in the White Sea. The burial and exhumation history is compared to available Apatite Fission Track (AFT) data for the Kola Peninsula and adjacent areas. Post-Devonian denudation rates on the shield rocks of the Kola Peninsula have varied in space and time. Around the periphery of the Kola Peninsula, low long-term denudation of shield rocks is indicated by the survival of Riphean cover rocks and Late Devonian lavas, kimberlite crater facies and near-surface emplacement of dykes. In contrast, in the main belts of KAP intrusions, 4–6 km of rock was removed in response to doming between 460 and 360 Ma. Deep denudation is indicated by the emplacement depths of alkaline intrusions and Phoscorite–Carbonatite pipes (PCPs). Erosion on the Kola Peninsula since 360 Ma has been far more limited. Extensive, shallow, late-stage magmatism associated with PCPs, dykes and the large alkaline intrusions in the KAP indicates that erosion depths nowhere exceeded 2 km. Post-Devonian denudation has removed <1 km of rock from the margins of the Kola Peninsula and from the backslope of the Saariselka–Karelia scarp in northern Finland. AFT data point to an important phase of erosion in the early Mesozoic but depths of unroofing of 3–5 km based on AFT cooling ages for this later phase are in conflict with the evidence of lesser erosion provided by the late-stage KAP intrusions and also require unrealistic depths of former Devonian to Triassic cover rocks. Mean denudation rates were greatest (up to 40 m/Myr) during the KAP magmatic phase. Post-Devonian rates across the Kola Peninsula and adjacent shield areas were much lower (<3–6 m/Myr) and are compatible with low long-term denudation rates for other cratons. Further resolution of longterm denudation patterns and rates on the Kola Peninsula requires the application of low-temperature thermochronometry, detailed examination of the regional geomorphology and firmer dating of ancient weathering episodes.

Habitat Associations of the Eastern Hognose Snake at the Northern Edge of Its Geographic Distribution: Should a Remnant Population Guide Restoration?

Heterodon platirhinos (Eastern Hognose Snake [EHS]) is a species of conservation concern in the northeastern United States. As an initial step toward potential restoration, we examined habitat associations of a peripheral population of EHS in New Hampshire. At the landscape scale, transmitter-equipped snakes were found most often in developed lands, followed by, in order of frequency, mixed forest, Pinus strobus/P. resinosa (Eastern White/ Red Pine) stands, and 7 other cover types. Within individual home ranges, snakes selected Tsuga canadensis (Eastern Hemlock) stands most often, followed by, in order of frequency, White/Red Pine stands, mixed forest, Fagus grandifolia/Quercus spp. (American Beech/ oak) stands, and 6 other cover types. Compared to random locations, microhabitat features at snake activity sites included higher ground-surface temperatures, closer proximity to wetlands, less canopy closure, and more abundant shrubs, ground debris, and rock cover. When combined with a previous study conducted in the same area, we found that cover-type associations (mesic forest) of this population differed from known affinities (open, xeric habitats) of EHS throughout much of its geographic distribution. Home ranges were also larger than those reported in most studies. We suspect our population persists because it occurs in a large parcel of land with limited human alteration and use. Habitat there is suitable but likely is not optimal. Such limitations should be considered when selecting sites to establish new populations of EHS in northern regions.

Spectral Indices for Estimating Exposed Carbonate Rock Fraction in Karst Areas of Southwest China

The quantitative estimation of the fractional cover of carbonate rock (CR) is critical for natural resource management and ecological conservation in karst areas. Based on the analysis of spectral properties of CR together with other land cover types, we proposed two CR indices (CRIs) and established the model that represents the relationships between the CRIs and the fractional cover of CR. Then, the fractional cover of CR was estimated by using the developed model. Experimental results on Landsat-8 Operational Land Imager images acquired at Southwestern China demonstrated the effectiveness of the developed model. Compared with other indices, the proposed CRIs show the highest correlations with the fractional cover of CR.

Thermal regime of rock and its relation to snow cover in steep alpine rock walls: gemsstock, central swiss alps

Snow cover influences the thermal regime and stability of frozen rock walls. In this study, we investigate and model the impact of the spatially variable snow cover on the thermal regime of steep permafrost rock walls. This is necessary for a more detailed understanding of the thermal and mechanical processes causing changes in rock temperature and in the ice and water contents of frozen rock, which possibly lead to rock wall instability. To assess the temporal and spatial evolution and influence of the snow, detailed measurements have been carried out at two selected points in steep north‐ and south‐facing rock walls since 2012. In parallel, the one‐dimensional energy balance model SNOWPACK is used to simulate the effects of snow cover on the thermal regime of the rock walls. For this, a multi‐method approach with high temporal resolution is applied, combining meteorological, borehole rock temperature and terrain parameter measurements. To validate the results obtained for the ground thermal regime and the seasonally varying snowpack, the model output is compared with near‐surface rock temperature measurements and remote snow cover observations.No decrease of snow depth at slope angles up to 70° was observed in rough terrain due to micro‐topographic structures. Strong contrasts in rock temperatures between north‐ and south‐facing slopes are due to differences in solar radiation, slope angle and the timing and depth of the snow cover.SNOWPACK proved to be useful for modelling snow cover–rock interactions in smooth, homogenous rock slopes.

Wind erosion potential of lacustrine and alluvial soils before and after disturbance in the eastern Great Basin, USA: Estimating threshold friction velocity using easier-to-measure soil properties

Abstract Disturbance of lacustrine and alluvial soils could increase aeolian dust emissions in the eastern Great Basin, but little is known about the susceptibility of these land surfaces to wind erosion. Threshold friction velocity (u∗t), a necessary parameter to estimate wind erosion potential, is difficult to accurately measure; methods to estimate u∗t from alternate measurements would be useful. We measured u∗t and sediment production rate with a portable wind tunnel, and quantified relationships between u∗t and eleven easier-to-measure soil surface properties for both undisturbed and disturbed lacustrine and alluvial soils in Snake Valley, Utah. Soil surface type and disturbance significantly influenced u∗t, sediment production rate, and the relationships between u∗t and easier-to-measure soil surface properties. Only soils with surficial rock fragments and weak physical crusts reached u∗t before disturbance, whereas all surface types reached u∗t following disturbance. Soils with weak physical crusts had the lowest average u∗t and highest average sediment production rate before and after disturbance. Surprisingly, however, disturbance reduced sediment production rate. Soils with weak physical crusts and surficial rock cover are likely the most susceptible to wind erosion and subsequent dust generation both before and after disturbance. Silt concentration and penetrometer resistance were significant predictors of u∗t in undisturbed soils with weak physical crusts and surficial rock cover. Following disturbance, clay concentration and aggregate stability were significant predictors for soils with hard salt crusts and surficial rock cover. Prediction of u∗t using alternate measurements is promising, but u∗t measurement uncertainty must be considered.

Relationships between an invasive crab, habitat availability and intertidal community structure at biogeographic scales

At local scales, habitat availability influences interactions between native and invasive species. Habitat availability may also predict patterns in native communities and invasive species at biogeographic scales when both native and invasive species have specific habitat requirements. The New Zealand porcelain crab, Petrolisthes elongatus, has invaded intertidal rocky shores around Tasmania, Australia, where it is found in high densities (>1800 m2) under rocks. A hierarchical sampling approach was used to investigate 1) the relationship between habitat availability (rock cover) and the biomass and abundance of P. elongatus, and 2) the relationship between P. elongatus biomass and native communities at local and regional scales. Invertebrate communities and habitat availability were sampled at multiple sites in the north and south regions of Tasmania. P. elongatus biomass and abundance were positively correlated with rock cover and patterns were consistent at the biogeographic scale (between regions). P. elongatus biomass was positively correlated with native species richness, biomass and abundance highlighting their co-dependence on rock cover. However, multivariate analyses indicated a different native community structure with increasing P. elongatus biomass. Flat, strongly adhering gastropods (chitons and limpets) were positively correlated with P. elongatus biomass, whereas mobile gastropods and crabs were negatively correlated with P. elongatus biomass. Despite local scale variation, there were clear consistent relationships between habitat-availability and the biomass of P. elongatus, and between native communities and the biomass of P. elongatus suggesting that the relationships between native and invasive species may be predictable at large spatial scales. Moreover, the strong relationships between P. elongatus biomass and changes in native community structure suggest a greater understanding of its impact is needed so that appropriate management plans can be developed.

U–Pb detrital zircon and 39Ar–40Ar muscovite ages from the eastern parts of the Karagwe-Ankole Belt: Tracking Paleoproterozoic basin formation and Mesoproterozoic crustal amalgamation along the western margin of the Tanzania Craton

The Karagwe-Ankole belt forms part of a complex system of orogenic belts in Central-East Africa that record the amalgamation of Archaean and/or Paleoproterozoic continental kernels in the Proterozoic. The actual timing of tectonic processes, including initial basin formation and subsequent deformation, is only poorly constrained so that the geodynamic significance of the Karagwe-Ankole belt within the broader system of Proterozoic orogens in Central-East Africa is not well understood. This paper presents U–Pb ages of detrital zircons constraining the age of sediments of the eastern parts of the Karagwe-Ankole fold belt overlying the western Tanzania Craton and 39Ar–40Ar muscovite ages from mylonites and phyllonites associated with the main phase of subsequent shortening and fold-and-thrust tectonics (D2).39Ar–40Ar muscovite ages from the main detachment between Archaean basement gneisses and imbricated cover rocks of the Kagera Supergroup in the eastern, frontal parts of the Karagwe-Ankole Belt constrain the timing of the main fabric forming event and thrusting (D2) to 1326±10Ma. This age is at the young end of the age range for the main phase of granite plutonism and mafic dyke emplacement that have previously been related to crustal extension and associated intracontinental rifting. If correct and representative for the main phase of deformation in the rest of the Karagwe-Ankole belt, the ages may rather point to a collisional event between the Congo and Tanzania Cratons west of the Karagwe-Ankole belt in Mesoproterozoic times, indicating a closer correlation with rocks of the Kibara Belt (sensu stricto) to the immediate south.U–Pb detrital zircon ages for the older Muyaga and overlying Bukoba Group of the Kagera Supergroup confirm the Paleoproterozoic timing of sedimentation from ca. 1780Ma, but before ca. 1568Ma. The presence of a distinct group of ca. 1750–1790Ma zircons in the Bukoba Group indicate uplift, erosion and subsequent reworking of sediments and volcanic units contained in the Lower Muyaga Group to the west. The ages also suggest a correlation between the Bwezigoro Group of SW Uganda and the Bukoba Group indicating the presence of a far more extensive Paleoproterozoic and/or Early Mesoproterozoic foreland basin overlying the western margin of the Archaean Tanzania Craton and Paleoproterozoic Uganda Block.

The Distribution of Cool Spots as Microrefugia in a Mountainous Area.

It has recently been proposed that microrefugia played an important role in species survival during past climate change events. However, the current distributions of microrefugia remain largely unknown. Wind-hole sites are areas affected by preferential flows of cool air generated in interstitial spaces created by rock fragments or colluvia. Alpine plant species occurring in lowland wind-hole sites isolated from alpine zones may be relicts of the last glacial period. Hokkaido, northern Japan, is known to contain many wind-hole sites in which alpine plant species can occur. Here we surveyed 55 wind-hole sites in the Kitami region, eastern Hokkaido, and observed two alpine plant species (lingonberry, Vaccinium vitis-idaea, and Labrador tea, Rhododendron groenlandicum ssp. diversipilosum var. diversipilosum) in 14 wind-hole sites. Statistical modeling showed that wind-hole sites are likely to occur in areas with high maximum slope angles and volcanic rock cover, and concave surfaces. Our predictions of wind-hole site distributions suggest that such topographic conditions are common in our study area, and that many undiscovered wind-hole sites exist. Ignoring microhabitats may greatly underestimate species distributions in topographically complex regions, and dispersed cool spots may also function as stepping stones and temporal habitats for cold-adapted species. Because these localized unique habitats usually occur in economically unproductive sites, identifying and protecting potential microrefugia (cool spots) would be a robust and cost-effective mitigation of climate change impacts.