一种新型峰林——武陵源石英砂岩峰林

本文探讨位于湘西武陵山脉中段的一种新的峰林地貌类型－－石英砂岩峰林的形态特征，形成过程与形成机理，认为石英砂岩峰林是由水平状石英砂岩受垂直与交叉节理的分割之后，在无溶蚀作用下形成的。     

张家界砂岩峰林景观成因机制

通过实地考察,室内遥感影像分析,得出如下结论：张家界石英砂岩峰林地貌岩层产状平缓,地壳水平上升,流水沿构造破裂面的节理侵蚀及重力崩塌作用造就了石英砂岩峰林地貌的基本形态。地貌形态的物质基础是特定的岩性。石英砂岩峰林地貌主要由方山、台地、峰墙、峰丛、峰林、石门、天生桥及峡谷、嶂谷等构成。其岩石胶结良好,刚性强,节理发育。物理风化很强烈,风化物和土壤十分疏松,内聚力小,抗蚀能力弱。存在着水土流失的潜在地质条件。另外,石英砂岩峰林地貌本身的地貌特点,水文气象要素都促使其山体风化、崩塌,景观消亡。为了保证景区的可持续发展,环境保护意义重大。     

河南渑池仰韶大峡谷“假岩溶”地貌特色景观及成因

针对仰韶大峡谷砂岩峰林地貌与砂岩溶孔等特色景观,通过野外地质调查,室内岩石测试与遥感影像分析,探讨了景区地貌景观的成因机理与演化。研究结果表明:仰韶大峡谷汝阳群石英砂岩岩层产状平缓,岩石坚硬刚性强,但垂直节理极其发育。第三纪地壳整体上升,地下水沿垂直节理侵蚀及重力崩塌作用造就了石英砂岩峰林地貌的基本形态,主要由石柱、峰丛、峰林、石门、天生桥及峡谷、嶂谷等构成。另外,怪洞形成的物质基础是特定的岩性,汝阳群上部北大尖组与白草坪组均夹白云质石英砂岩及砾屑白云岩透镜体,抗蚀能力弱,在强烈的物理风化与化学风化的联合作用下,水土流失形成空洞。     

喀斯特峰林峰丛地貌形态表达研究综述

峰林峰丛是形态最典型、特征最突出的喀斯特地貌,而喀斯特形态研究是喀斯特研究的基础。该文根据国内外相关文献资料,在全面梳理峰林峰丛地貌的概念内涵、形态特征、中西方不同表述的基础上,归纳总结了峰林峰丛地貌形态研究的发展历程。喀斯特峰林峰丛地貌形态研究经历了从定性描述到定量分析,从简单的数理统计、形态量计到分形分析,以及随多源、高分辨率数据的获取而发展起来的基于DEM和GIS空间分析技术进行精确定量分析等几个重要阶段。在分析总结上述峰林峰丛地貌形态研究过程及技术手段的基础上,指出现有的形态定量研究方法中存在的不足之处,对喀斯特峰林峰丛形态研究的前景做出展望,并提出峰林峰丛地貌形态研究的发展方向和亟待解决的关键问题。     

武陵源峰林地貌的成因及其开发与保护

论述武陵源峰林的地质风景特色及其成因,阐述峰林开成的历史背景与环境,探讨武陵源峰林的合理开发与保护之方。     

陆地地貌

P931．5 2007021126张家界岩性特征对峰林地貌形成的影响研究=The contri- bution of lithological component to sandstone forest landform genesis in Zhangjiajie,Hunan province/黄林燕,朱诚…//安徽师范大学学报．自然科学版．—2006,29(5)．—484～489岩性标本偏光镜鉴定及X荧光光谱分析发现,张家界石英砂岩SiO_2含量在79．40%-97．20%,生物碎屑灰岩     

广西环江锥状峰丛喀斯特景观演化机制

广西环江喀斯特世界自然遗产提名地是贵州荔波喀斯特世界自然遗产地的拓展地。环江喀斯特地貌发育演化受岩性、地质构造、断层、节理、裂隙和地下水文系统等因素影响。岩层由纯度较高的石灰岩和白云岩等可溶性碳酸盐岩构成,地壳运动使该地抬升,岩层受力发生褶皱并隆起断裂,断层节理发育;降雨、较高的温度以及地表-地下水对可溶性岩石进行侵蚀-溶蚀作用,使侵蚀基准面下降,河流下切,地表因长时间受剥蚀和溶蚀,地貌演化由幼年期经青年期进入壮年晚期。发育成峰丛谷地、洼地、峡谷及峰林洼地、谷地、盆地和多层洞穴等为主的形态多样的锥状喀斯特地貌景观。环江喀斯特自寒武纪以来经历了形成山间盆地和石炭系巨厚碳酸盐岩的沉积成岩阶段及喀斯特化作用,地貌发育演化经过3个主要阶段,即褶皱断块山地―盆地形成阶段、喀斯特峰丛―峰林发育阶段和喀斯特峡谷形成阶段。演化模式遵循峰丛洼地→峰丛谷地→峰丛峡谷→峰林洼地→峰林谷地地有序正向演替规律。揭示了热带-亚热带锥状喀斯特地貌发育主要阶段及演化过程。     

安徽齐云山丹霞地貌成因

齐云山丹霞地貌主要发育于中白垩统小岩组K₂x¹红色砂砾岩层中, 该区地貌发育主要受景德镇-祁门断裂带、江湾-街口挤压破裂带和开化-淳安褶断带三大断裂带控制。在白垩世该区经历了地块沉降, 成为陆上的断陷湖盆, 由此接受了巨厚的白垩系红层堆积。在新构造运动中, 该区经历了隆升过程, 巨厚的白垩系沉积物变成了海拔500~600 m的山体。白垩系红色砂砾岩在经历了垂直节理发育、风化破坏阶段及剥蚀搬运阶段后, 同时受岩性本身砂岩与砾岩在组分和结构上的影响, 差异性风化剥蚀显著, 因此形成了壮观的峰林、崖、洞、方山、城堡及天生桥景观。该区585 m、400 m和150 m处的三级裂点, 大致反映了该区新构造运动中三次主要的抬升过程。     

新疆阿克苏温宿大峡谷丹霞地貌特征及成因分析

由于造景岩石普遍为钙质和铁质胶结的砂岩和砾岩,丹霞地貌具有独特的景观特征和成因机制,同时因具有较高的科学和观赏价值而成为备受关注的旅游资源。东南湿润区丹霞地貌的研究程度较高,但是对西北干旱气候区丹霞地貌的研究还比较少见。以新疆阿克苏温宿大峡谷为研究对象,通过野外调查、样品显微镜观察、盐化学和元素地球化学实验以及ArcGIS面积高程积分（Hypsometric integral,HI）方法,探讨该地区丹霞地貌的特征和成因。结果显示：（1）研究区呈现峡谷、山峰及峰林景观,以发育陡崖泥流林和顶盖型石柱为特色,其造景岩石主要为新近纪河流相红色砾岩和砂岩,硬度较高的砾岩层为形成顶盖型石柱提供了有利保障。（2）红层位于温宿盐丘附近,岩石含盐量较高,主要的盐类型为氯化物、硫酸盐和硝酸盐。陡崖洞穴风化碎屑物样品中的大部分主量元素相对于表岩迁出,说明干旱气候下化学风化仍较活跃。（3）面积高程积分显示研究区南部HI值为0.61,处于幼年期,而北部HI值为0.38,处于老年期,整体地貌演化发育阶段差别较大。研究区虽然降水量较低,但河流侵蚀作用明显,同时构造也是影响丹霞地貌演化的主要因素。     

奇山异水张家界

张家界离济南 1500多公里，从济南至郑州，然后转乘北京开往怀化的 417次列车便可直达张家界。 张家界很大，面积约 264平方公里。从火车站到市区就有 10公里，从市区到各个景点就更远了，有时从一个景点到另一个景点要坐 2— 3个小时的汽车，所以去张家界旅游最好先找一家旅行社，请他们安排旅游和住宿，虽然收费高一点，但不至于盲人摸象，白跑许多山路，却看不到几个景点。 张家界很美，被誉为武陵山脉腹地吐出的一颗风景明珠，以罕见的石英砂岩大峰林峡谷而著称。在连绵不断的群山中，你会看到一片一片的大峡谷，峡谷中群峰林立，千姿…     

武陵源风景名胜区旅游发展的动力学分析

根据Butler旅游地生命周期理论,利用历史数据统计,分析了武陵源风景名胜区主要景区生命周期的动态演化趋势。实证研究表明,卫星景区宝峰湖和黄龙洞景区正处于发展阶段,成熟阶段是今后理想演进阶段。武陵源核心景区已处于成熟稳定阶段,要严格控制游客数量,调整旅游产品结构,避免滑向衰落阶段。最后,对武陵源风景名胜区旅游环境容量控制问题进行了探讨。     

旅游投资决定机制及其时空响应——以张家界为例

以张家界为例,分析了旅游投资决定机制的演变;运用旅游产业响应强度模型,分析武陵源区对旅游投资的时间响应特征,并阐述了在政府和市场作用下张家界旅游产业的空间响应和重构。结果显示：① 从投资决定机制演变看,投资制度安排决定了张家界旅游发展不同时期的投资主体差异,并随制度的演变,凸显了阶段性旅游投资分工格局。② 从时间响应看,在出现期,响应系数由1989年的0.1282增加到1992年的0.1341;在生成期,由1993年的0.1631提高到1999年的0.8511;在发展期,再从2000年的0.8767提高到2012年的1.1214,反映出旅游投资力度的强弱直接影响响应系数的大小。③ 从空间响应看,在政府、世界遗产管理制度和市场共同作用下,形成了以武陵源和天门山两个5A级景区为核心的空间格局,以及“景区游,城区住”的产业布局;经过重构后,旅游服务密度的排序为：桑植县<慈利县<永定区<武陵源区。     

Tectonic activation,source area stratigraphy and provenance changes in a rift basin: the Early Cretaceous Tucano Basin (NE‐Brazil)

Changes in sandstone and conglomerate maturity in tectonically active basins can be considered either as the product of climatic change or of tectonic restructuring of the feeder drainage system. Besides these regional controls, changes in the configuration of local sources can expressively affect basin fill composition. The Early Cretaceous fluvial successions of the Tucano Basin, a rift basin in northeastern Brazil related to the South Atlantic opening, contain one such case of abrupt change in maturity, marked by the passage from pebbly sandstone and conglomerate rich in quartz and quartzite fragments (Neocomian to Barremian São Sebastião Formation) to more feldspathic pebbly sandstone and conglomerate bearing pebbles of varied composition (Aptian Marizal Formation). Systematic analysis of stratigraphic and spatial variation in palaeocurrents and composition of pebbles and cobbles from both units, integrated with the recognition of fluvial and alluvial fan deposits distribution, revealed an abrupt decrease in maturity during the passage from the São Sebastião Formation to the Marizal Formation. This change is explained by exhumation of basement rocks and erosional removal of originally widespread Silurian to Jurassic sandstone and conglomerate units which were a major source of reworked vein quartz and quartzite pebbles to the São Sebastião Formation. Basin border faults activation during the deposition of the Marizal Formation caused adjacent basement uplift above the local erosional base level at the basin borders, whereas during the São Sebastião Formation deposition, the basin border fault scarps probably exposed mineralogically mature sedimentary units. The proposed model has important implications for interpreting changes in sediment maturity in rift basin successions, as similar results are expected where activation of basin border faults occurs after the erosional removal of older sedimentary or volcanic units that controlled syn‐rift successions composition.     

Tectono‐sedimentary Evolution of Early Pennsylvanian Alluvial Systems at the Onset of the Alleghanian Orogeny,Pocahontas Basin,Virginia

Foreland basin strata provide an opportunity to review the depositional response of alluvial systems to unsteady tectonic load variations at convergent plate margins. The lower Breathitt Group of the Pocahontas Basin, a sub‐basin of the Central Appalachian Basin, in Virginia preserves an Early Pennsylvanian record of sedimentation during initial foreland basin subsidence of the Alleghanian orogeny. Utilizing fluvial facies distributions and long‐term stacking patterns within the context of an ancient, marginal‐marine foreland basin provides stratigraphic evidence to disentangle a recurring, low‐frequency residual tectonic signature from high‐frequency glacioeustatic events. Results from basin‐wide facies analysis, corroborated with petrography and detrital zircon geochronology, support a two end‐member depositional system of coexisting transverse and longitudinal alluvial systems infilling the foredeep during eustatic lowstands. Provenance data suggest that sediment was derived from low‐grade metamorphic Grenvillian‐Avalonian terranes and recycling of older Palaeozoic sedimentary rocks uplifted as part of the Alleghanian orogen and Archean‐Superior‐Province. Immature sediments, including lithic sandstone bodies, were deposited within a SE‐NW oriented transverse drainage system. Quartzarenites were deposited within a strike‐parallel NE‐SW oriented axial drainage, forming elongate belts along the western basin margin. These mature quartzarenites were deposited within a braided fluvial system that originated from a northerly cratonic source area. Integrating subsurface and sandstone provenance data indicates significant, repeated palaeogeographical shifts in alluvial facies distribution. Distinct wedges comprising composite sequences are bounded by successive shifts in alluvial facies and define three low‐frequency tectonic accommodation cycles. The proposed tectonic accommodation cycles provide an explanation for the recognized low‐frequency composite sequences, defining short‐term episodes of unsteady westward migration of the flexural Appalachian Basin and constrain the relative timing of deformation events during cratonward progression of the Alleghanian orogenic wedge.     

湖南省县域乡村反贫困绩效评价与空间分异特征

综合运用熵值法、地理探测器等方法,从基本生存绩效、自身发展绩效,县域扶贫绩效3个方面构建指标体系,对湖南省51个贫困县2017年反贫困绩效空间地域分异特征及其影响因素进行研究。结果表明：① 湖南省贫困农户一般能满足基本的生存需要;自身发展绩效水平得分较高的区域大多处于武陵源区、鹤城区等城市市区周围以及罗霄山片区,而雪峰山脉周围县市则普遍较低;县域扶贫绩效水平高的区域分布较为零散,大致位于各城区周围,而省城或西北的少数民族聚集区以及中南部绩效水平还有待提高。② 反贫困绩效总体上呈现出高、中、低3种绩效水平交替分布的空间特征,愈靠近武陵源区、鹤城区和长株潭地区的贫困县市,综合反贫困绩效水平愈高。③ 县域发展情况是影响湖南省反贫困绩效的决定性因素,农户条件与乡村状况是基础性因素,自然条件是重要因素,各因子间交互作用的影响远大于单因子,不存在独立作用的因素,体现出湖南省反贫困绩效影响因素的复杂性特征。     

旅游驱动的乡村振兴实践及发展路径

归纳案例地为摆脱贫困适应时代需要的具体实践过程,从“三个转向”（产业转向、管理转向、空间转向）解析旅游驱动的乡村振兴实践,总结旅游业驱动乡村振兴的一般机制及路径,为理解旅游业在乡村振兴中发挥的作用提供新视角。研究发现：① 发展旅游业是旅游资源富足的贫困地区脱贫致富,实现乡村振兴的主渠道和中坚力量;② 武陵源区主导产业由林业转向旅游业这一过程,为实现乡村振兴实践提供动力基础;景区经营权与管理权的分离,促进乡村经济的发展;“景区游,城区住”的格局加速了武陵源区乡村振兴的步伐;③ 武陵源区在长期发展实践中形成了“旅游产业发展→旅游小镇发育壮大→乡村振兴→城乡融合”之实践模式;④ 加快推进旅游业态创新,不断增加农民收入,加强乡风建设,以政府为主导,加速基础设施建设是资源富足贫困地区实现乡村振兴的必由之路。     

武陵源水体环境质量现状分析及评价

武陵源自1992年被列为世界自然遗产以来,由于重开发、轻保护,其水体环境受到了明显影响,水体质量基本上呈现逐年下降的趋势。本文选取对水体环境质量影响较大的BOD5、COD、TN、TP、As、MnO4-作为评价因子,对武陵源主要水系金鞭溪和索溪沿途4个主要断面进行监测,并利用模糊综合评价法,进一步研究武陵源水体污染程度,探讨武陵源水体环境变化规律。评价结果显示:水绕四门、吴家峪口、紫草潭断面的水体质量级别为II级,老磨湾断面的水体质量级别为III级,评价结果与实际监测数据基本一致。在此基础上,有针对性地提出了水体环境质量改善措施,为提高世界自然遗产地武陵源水体环境质量提供科学依据。     

湖北潜江凹陷北部古近系孔隙卤水矿床特征及成因

深层卤水是我国重要的液体矿产资源,其中含有钾、锂、铷、铯、溴、碘、硼等高价值元素,具有广阔的综合利用开发前景。通过研究江汉盆地潜江凹陷北部地区潜江组卤水矿床的储层以及水化学特征,对该地区卤水成因及其成藏条件进行了分析。深层卤水赋存于潜江凹陷古近系潜江组砂岩中,水化学类型以硫酸钠亚型为主,其次为碳酸盐型、氯化钙型和硫酸镁亚型。总矿化度在221.3~323.5 g/L之间,平均值为274.08 g/L,酸碱度为4.5~6.5。潜江组卤水浓缩程度不高,变质程度低,体系较为开放。结合卤水矿床的水化学和储层特征,盆地卤水来源主要有火山—地热水的补给、基性火山岩的水—岩反应和蒸发岩的地下溶解。位于潜江凹陷北缘的钟西地区砂岩厚度大,具有巨大的储集空间,在构造—岩相作用下可能储藏了来自潜江凹陷南部古盐湖的卤水,因此潜江凹陷北部钟西地区砂岩具有较好的成藏条件。     

Petrochemical and Tectonogenesis of Granitoids in the Wuyo-Gubrunde Horst,Northeastern Nigeria: Implication for Uranium Enrichment

The Wuyo-Gubrunde Horst in the northeastern Nigeria consists of migmatite gneiss, unaltered, altered, and sheared porphyritic granites, pegmatites, aplites, basalts, and sandstone. Uranium has been reported in rhyolite, sheared rocks, and sandstone within the area. The petrogenesis of the granitoids and associated rocks in the area was evaluated in the light of new geochemical data, which showed that the U content of altered porphyritic granite is highest and hydrothermal-related. The granitoids are metaluminous, sub-alkaline, and S-type granite, and have evolved by partial melting of crustal material emplaced at moderate depth of 20–30 km in a syn-to late-collisional within-plate tectonic setting. The negative Eu/Eu* anomaly and high (La/Yb)_N ratio of the granitoids indicate magma fractionation. The low SiO₂ (<53%) and high Fe₂O₃ (10%) of the altered porphyritic granite compared to other similar rock units suggest pervasive alteration. The associated basalts are tholeiitic, emplaced within continental plate tectonic setting, and enriched in Ni, V, Nb, Sr, and light rare earth elements, and they have SiO₂, Fe₂O₃, V, Th, and Co contents that are similar to those of the altered porphyritic granites. The U occurrence in the Wuyo-Gubrunde Horst is believed to be sourced from the adjoining Bima sandstone in the Benue Trough, which locally contains carbonaceous zones with anomalously high concentrations of U. The Fe²⁺/Fe³⁺ redox fronts formed by alteration of the iron-rich basalts provided the requisite geochemical barrier for U-bearing hydrothermal fluid, causing enrichment of U leached and mobilized from the sandstone through fractures in the rocks.     

Tectonic,sedimentary and diagenetic controls on sediment maturity of lower Cambrian quartz arenite from southwestern Baltica

Lower Cambrian quartz arenitic deposits have a worldwide occurrence. In this study, petrographic and mineralogical analyses were carried out on samples from the quartz‐rich Ringsaker Member of the Vangsås Formation from southern Norway and the corresponding Hardeberga Formation from southern Sweden and on the Danish island of Bornholm. The quartz arenite is almost completely quartz cemented and has an average intergranular volume of 30%. The quartz cement is the dominating cause for porosity loss. Dissolution along stylolites and microstylolites is suggested to be the primary and secondary source for the quartz cement respectively. The quartzose sandstone from southern Norway was severely cemented prior to the Caledonian Orogeny, thus limiting the tectonic influence on diagenesis during thrusting. For most samples, authigenic clay minerals and detrital phyllosilicates represent ca. 5% of the present‐day composition. This, together with a low feldspar content, of on average 4%, indicates that the sediment was extremely quartz‐rich already during deposition. The low amount of feldspar prior to burial and the formation of early diagenetic kaolinite point to weathering, sediment reworking and early diagenesis act as important controls on sediment maturity. The large variation in clay‐mineral and feldspar content between the localities, as well as within the sandstone successions, can be explained by different palaeogeography on the shelf during deposition and subsequently dissimilar subjection to reworking and early diagenetic processes. Weathering in the provenance area, reworking in the depositional shallow‐marine environment and meteoric flushing during the burial stage are suggested to explain the high mineralogical maturity of the lower Cambrian sandstone from southwestern Baltica. These processes may generally account for similar quartz‐rich shallow‐marine sandstone units, deposited as a result of intensive continental denudation and during temperate to subtropical and moderately humid conditions.