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1.
A new Geologic Time Scale, with special reference to Precambrian and Neogene   总被引:10,自引:0,他引:10  
A Geologic Time Scale (GTS2004) is presented that integrates currently available stratigraphic and geochronologic information. Key features of the new scale are outlined, how it was constructed, and how it can be further improved. The accompanying International Stratigraphic Chart, issued under auspices of the International Commission on Stratigraphy (ICS), shows the current chronostratigraphic scale and ages with estimates of uncertainty for all stage boundaries. Special reference is made to the Precambrian part of the time scale, which is coming of age in terms of detail, and to the Neogene portion, which has attained an ultra-high-precision absolute-age calibration.  相似文献   

2.
国际地层委员会前不久公布了2 0 0 4年“国际地层表”,并专门提出了“2 0 0 4—2 0 0 8年前寒武纪年表参考方案”。在2 0 0 4年版“国际地层表”中,新建了埃迪卡拉系,其时限从6 30 Ma至5 4 2 Ma。“2 0 0 4—2 0 0 8年前寒武系划分参考方案”指出应该根据唯一客观的物理标准——现存的岩石记录,对前寒武纪地质年表重新进行界定。前寒武纪的地层界线应标定于地层记录中的关键事件或转变点上,以突出反映地球系统演化的巨变。在介绍有关埃迪卡拉系的背景、地质特征和时限的同时,对“参考方案”中有关前寒武系划分原则和具体划分方案的新思路进行了介绍和评述,对“参考方案”中值得商榷的问题进行了初步分析,并对我国前寒武纪年代表制定中有关重点提出了建议  相似文献   

3.
沉积记录中的古气候周期及其在高频层序形成中的意义   总被引:2,自引:1,他引:1  
目前认为,构造升降、气候所控制的湖平面变化以及沉积物的供给对陆相湖盆层序发育的范围、厚度、演化阶段及层序边界的形成起着主要控制作用,而对于同一湖盆演化的不同阶段,则是不同因素对各级层序的形成起着主要的控制作用.某一时期,构造因素决定着较大级别层序边界的形成;而在构造活动相对稳定期,基于天文旋回的气候周期是高频层序形成的主要控制因素.在以往的研究中,对气候周期的深入分析一直较薄弱.加强气候因素的研究,从而更精确地解析高频层序的成因,进行高频层序的划分、对比,预测优质储层和烃源岩的特征及分布是今后能源和盆地研究中必不可少的一个工作重心.另外,随着"天文年代表"概念的提出,天文轨道旋回的方法已成为确定地层年代的一个重要手段.  相似文献   

4.
中国地层学研究近期面临的主要问题   总被引:1,自引:0,他引:1  
地层中包含了地球演化过程的许多重要信息,它是建立全球地质年代系统的重要基础。统一年代地层系统的建立有利于促进基础地质工作、矿产资源勘查、地质环境评价和地质灾害预测与防治等各项事业的发展,因此一直受到广大地质工作者的高度重视。目前在《国际地层表》已建的110个阶中,已有65个全球界线层型剖面和点位(简称GSSP)被国际地层委员会和国际地质科学联合会批准确认,其中有10个GSSP被确立在中国,我国是拥有GSSP最多的国家。在中国区域年代地层表的102个阶中,也有59个阶得到了较深入的研究,并建立了部分地层单位的划分对比标准。虽然我国的地层学研究取得了许多重要成果,但是在中国区域地层标准的建立与完善以及区域地层单位与GSSP的对比、变形和变质较强烈地区地层学研究方法的确定、广泛分布的中新生代陆相地层划分对比、中国典型地层剖面保护和规范化研究等方面还存在诸多尚未解决的重要问题,急待深入研究。  相似文献   

5.
中国陆相侏罗、白垩系划分对比述评   总被引:44,自引:7,他引:37  
陈丕基 《地层学杂志》2000,24(2):114-119
对我国东北、西南和东南沿海地区目前常用的陆相侏罗、白垩系的划分、对比方案的精度及其与海相标准分阶的对比证据进行了扼要分析和述评 ,指出东北地区陆相白垩系序列可以划分出 13个组 ,其精度已赶上了海相白垩系 12个阶的标准 ,而且许多组已找到了将海陆相地层进行对比的联系化石分子 ,亦具备了陆相地层建阶的条件。同时认为我国中生代陆相地层划分对比表中以往很少表现出地层缺失 ,大多数地区似乎从下向上都存在一个完整的沉积序列 ,这是与陆相地层形成的实际不相符的 ,今后要进一步做工作。  相似文献   

6.
<正> 1990年9月,我国地质出版社出版了由王鸿祯、李光岑合编的《国际地层时代对比表(Correlation Table of Stratigraphic Subdivision,CTSS)》,及时地把1989年7月17日由国际地层委员会通过的《全球地层表(Global Stratigraphic Chart,GSC)》介绍到国内并且增补了《中国地层时代表(A Stratigraphic and Geologic Time Scale of China,SGTSC)》和《地质时代表(A Geologic Time Scale,GTS)》,有力地推动了我国的地层学研究工作,起到了为地质勘探服务的积极作用。  相似文献   

7.
The Cryogenian succession of the Northern Flinders Ranges reveals a complex sedimentary record between the Sturtian and Marinoan glacial deposits. A major unconformity separates the Sturtian and Marinoan-aged sedimentary successions in the area. This forms a subaerial erosion surface with terrestrial and marginal marine infill directly above the Angepena and Balcanoona Formations in their respective localities. This exposure surface is here correlated with the previously documented submarine unconformity between the Yankaninna Formation and the underlying deep marine Tapley Hill Formation. This erosional event provides a chronostratigraphic marker horizon that coincides approximately with thepreviously defined Sturtian–Marinoan Time Series boundary in the Northern Flinders Ranges. These stratigraphic relationships also constrain lateral facies relationships between the Oodnaminta ReefComplex (Balcanoona Formation) and the Angepena Formation. Similarly, the shallow-water Weetootla Dolomite is correlated with the deeper water carbonates of the Yankaninna Formation.  相似文献   

8.
We present a high-resolution sedimentological analysis of Barremian–Aptian shallow-water carbonates from two cores (S. Maria 6 and 4) that were drilled in the central Apennines (central Italy) and one section (Monte Faito) that crops out in the southern Apennines (southern Italy). The aims of this work are (a) to propose a high-resolution correlation of sections that are located approximately 170 km apart in different tectonic units and paleogeographic domains using a microstratigraphic (cm-scale) approach and (b) to reveal global and regional mechanisms that control the stratigraphic architecture of these carbonate platform strata.A composite S. Maria section was assembled by integrating the sedimentologic and biostratigraphic analyses of the two cores, which overlap each other across the Barremian–Aptian boundary. Both the S. Maria and the Monte Faito sections show repetitive facies patterns that are expressed as elementary cycles, which are hierarchically grouped into bundles and superbundles. The elementary cycles are meter-scale sedimentary units that are bounded by subaerial erosion surfaces, which directly overlie subtidal deposits. This implies that they formed under the influence of relative sea-level fluctuations. In both sections, the superbundles are organized into Transgressive/Regressive Facies Trends (T/RFTs), which are considered to be expressions of lower-frequency relative sea-level changes.These deposits, like their Cretaceous analogues of other areas of the Apennines, show evidence of astronomically controlled eustatic oscillations, which are reflected in the hierarchical organization of their stacking patterns. They also exhibit a sequence-stratigraphic configuration that is best recognizable in the superbundles and T/RFTs. Based on integrated stratigraphic criteria, a high-resolution regional correlation between S. Maria and Monte Faito was developed and compared with the reference section of Monte Raggeto (M. Maggiore, southern Apennines, Italy), where biostratigraphic and cyclostratigraphic studies have been complemented by magneto- and isotope-stratigraphy.We also propose a chronostratigraphic correlation between our T/RFTs and the Tethyan stratigraphic cycles of Hardenbol et al. (1998). Based on the cyclostratigraphic interpretation and orbital chronostratigraphy of the studied interval, we estimate a minimum duration of 5.2 my for the Barremian interval, which is similar to the 4.5 my duration from the Geological Time Scale of Gradstein et al., (2012).  相似文献   

9.
The Regional Stratigraphic Scale (RSS) of the Permian deposits in northeastern Russia represents the only complete stratigraphic succession of Permian marine deposits distinguished in Russia, which serves as a standard at the correlation of Permian deposits of all regions of the eastern part of the Boreal Biogeographic Superrealm. However, a high level of faunistic endemism makes it extremely difficult to correlate directly stratons of the RSS with stages of the International Stratigraphic Scale (ISS) of the Permian deposits. The first U–Pb SIMS age datings of zircons from felsic tuffs of the Omchak Formation of the Ayan-Yuryakh Anticlinorium (the lower part of the Permian Khivachian Horizon of the RSS of northeastern Russia) allowed us to obtain the important reference level for the Upper Permian subdivision of the Permian RSS. The zircon age of 257.1 ± 3.0 Ma is in good agreement with the stratigraphic position of the studied sample, which makes it possible to correlate the surrounding deposits with the Wuchiapingian Stage of the Permian deposits in the International Stratigraphic Scale.  相似文献   

10.
从关键地质事件看华南的前寒武系划分   总被引:12,自引:1,他引:12  
吴根耀 《地层学杂志》2006,30(3):271-286
2004年的《国际地层表》与以往“国际地层表”的最大不同是对前寒武系的划分原则,即:以保存在地质记录中的地球系统巨变中的关键地质事件作为划分地层单位的界线,并据之建立“自然的”前寒武纪地质年表。在这一思想指导下,本文以川滇赣三省为重点,重新审视华南的前寒武系资料,分中太古—新太古代、跃迁期、古元古—中元古代和新元古代四大阶段阐述了关键地质事件并讨论了其在大陆岩石圈形成和演化中的构造意义。这四大阶段的主要构造面貌分别是:片麻岩基底和绿岩带盆地,古陆壳的形成与裂解,第一个超级大陆即哥伦比亚(或称努纳)超大陆的形成与离散,板块构造体制下罗迪尼亚超大陆的汇聚与离散,反映了大陆岩石圈的形成和由低级向高级的演化,因而每一阶段都有不同于前一阶段的沉积建造、火成岩类型及组合、变质作用、构造样式、构造线方向、变形方式和成矿作用。基于这些事件介绍了前寒武系的分布,列述了若干条相对连续的地质剖面上所见的这四大阶段的代表性地层序列及其对比方案。文章认为“参考方案”对前寒武系研究有推动和导向作用,并探讨了地层研究具体操作中关于事件的内容、事件与过程、现存地质记录的残破不全等问题。  相似文献   

11.
Data are provided on the new Ordovician stage standard of the International Stratigraphic Chart: Tremadocian, Floian, Dapingian, Darriwilian, Sandbian, Katian, and Hirnantian. Graptolite and conodont zonal and infrazonal successions are used for a precise estimation of the chrono- stratigraphic position of the boundaries of the previous and newly proposed Ordovician regional stratigraphic units (horizons) in the western Altai–Sayan Folded Area. The chronostratigraphic position of the boundaries of most of the Ordovician formations showing a wide lateral distribution in southern Siberia has been described in detail in terms of the new stage standard of the General Stratigraphic Scale of Russia.  相似文献   

12.
The sediment record from the Piànico palaeolake in the southern Alps is continuously varved, spans more than 15 500 years, and represents a key archive for interglacial climate variability at seasonal resolution. The stratigraphic position of the Piànico Interglacial has been controversial in the past. The identification of two volcanic ash layers and their microscopic analysis provides distinct marker layers for tephrochronological dating of these interglacial deposits. In addition to micro‐facies analyses reconstructing depositional processes of both tephra layers within the lake environment, their mineralogical and geochemical composition has been determined through major‐element electron probe micro‐analysis on glass shards. Comparison with published tephra data traced the volcanic source regions of the Piànico tephras to the Campanian volcanic complex of Roccamonfina (Italy) and probably the Puy de Sancy volcano in the French Massif Central. Available dating of near‐vent deposits from the Roccamonfina volcano provides a robust tephrochronological anchor point at around 400 ka for the Piànico Interglacial. These deposits correlate with marine oxygen isotope stage (MIS) 11 and thus are younger than Early to Middle Pleistocene previously suggested by K/Ar dating and older than the last interglacial as inferred from macrofloral remains and the geological setting. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

13.
From stratigraphic investigations of 38 piston and vibro cores, four fine-grained Late Weichselian sediment units can be defined in the southern Kattegat. A continuous stratigraphic record of the Late Weichselian sediments cannot be established from single cores due to the uneven distribution of the units, but by compilation of relative stratigraphies a composite record can be determined for sediments deposited between approximately 13,500 and 10,000 BP. The sediments contain both lithological and biostratigraphical evidence that the Baltic Ice Lake was suddenly drained through the Öresund Strait at about 12,700 BP. This drainage route appears to have been unchanged until about 10,300 BP when a passage opened in south central Sweden through which the final drainage of the Baltic Ice Lake took place. The Younger Dryas cold event appears to have had only marginal effects on the marine benthic life in the region. The data also indicate that drainage of fresh Baltic water through the Öresund Strait was the driving force for an inflow of marine water from the Skagerrak North Atlantic Ocean into the southern Kattegat, as occurring at the present. This paper is a contribution to IGCP 253, Termination of the Pleistocene .  相似文献   

14.
The late Miocene mammalian record in Samos Island, Greece, is extremely important for the Eurasian Neogene mammalian history and chronology. However, due to the mixed nature of old fossil collections and controversies on the stratigraphic position of fossil quarries, great confusion has arisen concerning the recognition of distinct faunal assemblages, their age(s) and biostratigraphic significance. This paper presents the magnetostratigraphy of the late Miocene continental deposits of the fossiliferous Mytilinii Basin, Samos Island, Greece. Old and new sites are stratigraphically controlled with accuracy and correlated with each other. The magnetostratigraphy of seven individual sections, covering the entire Mytilinii Formation, provides good correlation with the Geomagnetic Polarity Time Scale (GPTS). These results, as well as the relocation and precise litho- and magnetostratigraphic correlation of the old and new mammal localities, combined with new and reviewed paleontological data and thorough studying of the numerous radiometric dates, allowed us to define five biostratigraphic horizons. Their correlation with, and implications to the European Neogene mammal chronology ages and zones make up the following discussion and provides a modified determination of the middle Turolian (MN 12) boundaries.Abbreviations GPTS Geomagnetic Polarity Time Scale - IPGP Institute de Physic du Globe de Paris - MGL Musée Cantonal de Géologie, Lausanne - MNHA Museum of Natural History of the Aegean, Samos - BMNH Natural History Museum of London - Q quarries - Fm Formation  相似文献   

15.
《Quaternary Science Reviews》2004,23(23-24):2485-2500
A detailed tephrostratigraphy supported by accelerator mass spectrometry (AMS) 14C dating and isotopic and geochemical analyses has been carried out for a deep-sea core collected from the Southern Adriatic Sea, which spans the last 18 14C kyr. Fourteen ash layers have been recognized in the marine core and the origin was determined by comparing their age and geochemistry with tephra detected in terrestrial deposits. The geochemical signatures of marine ash layers indicate a prevailing Campanian and subordinate Etnean and Eolian provenances. Collectively, they are attributed to sources in the Phlegraean Fields (LAM-Lagno Amendolare; LN1/LN2-GM1; C-2/NYT-Neapolitan Yellow Tuff; C-1-Agnano Pomici Principali; AMS/PF-Agnano Monte Spina; AST-Astroni), Somma-Vesuvius (L9-Pomici di Base; L8-Greenish), Mount Etna (Et1-Y1-Biancavilla Ignimbrite), Lipari (E-1-Gabellotto-Fiumebianco) and Palinuro seamount (Pal 1). Some of these eruptions have been detected for the first time in marine cores (Astroni, LAM, L9, L8), and three were detected and dated by marine tephra (LN1, LN2, and Pal 1) providing new more precise stratigraphic markers for the last 18  kyr in the South Adriatic marine record.  相似文献   

16.
Disperse and punctual studies; absence of integration of data ranging from local to regional focus; interpretations based only on lithostratigraphic features; and interpretation of data premised on an allochthonous origin of the Caribbean plate, are some of factors that increase the confusion and uncertainty in understanding the Sinú-San Jacinto Basin. The sedimentary record of Upper Cretaceous to Eocene has been traditionally interpreted as the record of deep-water settings. However, recently these sediments have been related to shallow marine and deltaic settings. Second problematic point is about the deposition environment of the Oligocene to Late Miocene succession. Some studies suggest canyons, turbidites and sediments deposited in deep-water settings. However, recent studies propose deltaic and shallow marine settings. The last stratigraphic problem is related to the controversial fluvial vs. shallow marine interpretations of the Pliocene sediments. Based upon seismic stratigraphic analysis in recent and reprocessed 2D seismic data, integrated with well data, we propose chronostratigraphic charts for the northern, central and southern zones of the Sinú-San Jacinto Basin. Twenty seismic facies based on amplitude, continuity, frequency and geometry of seismic reflectors and twelve seismic sequences were recognized. The seismic stratigraphic analysis in this study suggests that the sediments of Upper Cretaceous to Paleocene/Eocene were associated to continental to shallow marine settings. Lagoons, coastal plain and carbonate platform dominated during this period. The Oligocene to Middle Miocene record was characterized by deep-water deposition, whereas the Late Miocene to recent sedimentation was characterized by falling base level, characterized by deltaic and fluvial deposits. Five syn-rift sequences with wedge-shaped geometry were identified in this study. Three Triassic to Jurassic syn-rift sequences were characterized by seismic facies typical of fluvial to lacustrine and flood plain sedimentation. Two Cretaceous to Paleocene syn-rift sequences were characterized by seismic facies related to lagoons to coastal plain settings. Normal high-angle faults with a northeast-southwest direction related to rifting processes controlled the development of these sequences. The sheet-drape post-rift section was characterized by passive margin settings in the northern part of the Sinú-San Jacinto Basin and by diachronic tectonic inversion of older normal faults during Cenozoic, predominantly in the central and southern zones. The stratigraphic record related to the Mesozoic to Early Cenozoic rifting; the shallow marine sedimentation during Eocene and the tectono-stratigraphic continuity across the northern Colombia and northwestern Venezuela is coherent and well explained by the in situ origin of the Caribbean plate and is not explained by the “allochthonous” model.  相似文献   

17.
A detailed integrated stratigraphic study was carried out on middle Miocene fluvial successions of the Upper Freshwater Molasse (OSM) from the North Alpine Foreland Basin, in eastern Bavaria, Germany. The biostratigraphic investigations yielded six new localities thereby refining the OSM biostratigraphy for units C to E (sensu; Heissig, Actes du Congres BiochroM’97. Mem Trav EPHE, Inst Montpellier 21, 1997) and further improving biostratigraphic correlations between the different sections throughout eastern Bavaria. Radioisotopic ages of 14.55 ± 0.19 and 14.88 ± 0.11 Ma have been obtained for glass shards from the main bentonite horizon and the Ries impactite: two important stratigraphic marker beds used for confirming our magnetostratigraphic calibration to the Astronomical Tuned Neogene Time Scale (ATNTS04; Lourens et al. in Geologic Time Scale 2004, Cambridge University Press, 2004). Paleomagnetic analysis was performed using alternating field (AF) and thermal (TH) demagnetization methods. The AF method revealed both normal and reverse polarities but proofs to yield unreliable ChRM directions for the Puttenhausen section. Using the biostratigraphic information and radioisotopic ages, the magnetostratigraphic records of the different sections are tentatively correlated to the Astronomical Tuned Neogene Time Scale (ATNTS04; Lourens et al. in Geologic Time Scale 2004, Cambridge University Press, 2004). This correlation implies that the main bentonite horizon coincides to chron C5ADn, which is corroborated by its radioisotopic age of 14.55 Ma, whereas the new fossil locality Furth 460, belonging to OSM unit E, probably correlates to chron C5Bn.1r. The latter correlation agrees well with the Swiss Molasse locality Frohberg. Correlations of the older sections are not straightforward. The Brock horizon, which comprises limestone ejecta from the Ries impact, possibly correlates to C5ADr (14.581–14.784 Ma), implying that, although within error, the radioisotopic age of 14.88 ± 0.11 Ma is somewhat too old. The fossil localities in Puttenhausen, belonging to the older part of OSM unit C, probably coincide with chron C5Cn.2n or older, which is older than the correlations established for the Swiss Molasse. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.  相似文献   

18.
Defining the Jurassic-Cretaceous boundary is a controversy in stratigraphic study of the world. It has been widely accepted that this boundary can be defined at the bottom of Berriasian in Tethys, with the appearance of the ammonite Berriasella jacobi dating to ca. 145 Ma. However, it is difficult for the widespread terrestrial deposits in China to correlate with the international standard of marine facies. The Somanakamura Group in Japan is represented by a succession of marine-continental transitional strata. It provides a bridge of marine and nonmarine stratigraphic correlation. The ammonite and radiolarian fossils preserved in this group suggest an age from Bajocian to early Valanginian. The J-K boundary was defined in or atop the Tomizawa Formation of the group according to the ammonite data. The present authors study the fossil spores and pollen newly found from the Tomizawa and Koyamada formations. Three assemblages have been recognized. They are Assemblage 1 (Cyathidites-Classopollis) from the upper part of the Tomizawa Formation, Assemblage 2 (Cyathidites-Jiaohepollis) from the lower part of the Koyamada Formation, and Assemblage 3 (Cyathidites-Spheripollenites-Ephedripites) from the middle to upper part of the Koyamada Formation. With the reference of ammonite evidence, the J-K boundary can be defined between Assemblage 1 and Assemblage 2. This palynological J-K boundary can be correlated with that of terrestrial sequence in China. However, local biostratigraphy imply that the continental J-K boundary in China is of 135 or 137 Ma age. It has a considerable discrepancy from the marine standard. Biogeographically, the distribution pattern of spores and pollen in southern China is in accordance with that in the Somanakamura Group, which parallels the Tuchengzi Formation in northeastern China. By the palynological correlation between the Somanakamura Group and the strata in southern China, and then with the sequence in northeastern China, it is suggested that the continental J-K boundary is located in the Tuchengzi Formation.  相似文献   

19.
南海北部深水区LS33a钻井微体古生物年代地层格架   总被引:1,自引:0,他引:1  
南海北部琼东南盆地深水区接收了渐新世以来数千米厚的海相沉积地层,蕴藏着丰富的微体古生物化石。对深水区LS33a钻井岩芯的取样和化石鉴定,识别出21个浮游有孔虫化石带(N22带~P19带)和12个钙质超微化石带(NN19带~NP24带)。通过与大洋钻探(ODP)在南海实施的184航次的钻探结果和“国际年代地层表(2012)”等的对比分析,探讨了化石事件的地质年代意义,构建了LS33a钻井生物年代地层格架。在此基础上,讨论了更新统与上新统、上上新统与下上新统、上新统与中新统、上中新统与中中新统、中中新统与下中新统、中新统与渐新统、上渐新统与下渐新统之间地层界线位置以及崖城组、陵水组、三亚组、梅山组、黄流组、莺歌海组和乐东组地层的时代归属,建立了适用于南海北部深水区的高分辨率综合年代地层格架。  相似文献   

20.
The >25 ka volcaniclastic ring-plain succession in south-west Taranaki has been remapped to establish a much more detailed understanding of the older stratigraphic record of Mt. Taranaki. Coastal cliff exposures show a range of volcaniclastic lithofacies, including debris-avalanche and lahar deposits, and allow a detailed chronological reconstruction of past volcanic and sedimentary events. Five new debris-avalanche deposits were identified, and their distribution in coastal cross-sections mapped. In addition, four previously described units were renamed and their stratigraphic position and lateral extent redefined. Chronostratigraphic control of the younger (<50 ka) sequence was obtained by radiocarbon dating of wood found within, or peat interbedded with, the deposits. Emplacement ages of the older units were estimated from their stratigraphic position and underlying marine wave-cut surfaces. Overall, at least 14 widespread debris-avalanche deposits occur within the <200 ka ring-plain record of Mt. Taranaki, suggesting one major edifice failure on average every 14,000 years, with an increase in frequency since 40 ka. The stratigraphic reconstruction of the ring-plain succession showed that the same pattern of deposition was repeatedly produced throughout the existence of Mt. Taranaki. Depending on their sedimentological characteristics, the different volcanic and sedimentary lithofacies can be related to phases of edifice-construction or collapse events. Based on the identified cyclic sedimentation pattern, we present a new episodic stratigraphy that integrates existing and new lithostratigraphic units into a coherent chronostratigraphic framework that can be applied to the entire volcanic and volcaniclastic succession at Mt. Taranaki. This model takes into account the complex geological processes that have taken place on the volcano and provides a more uniform stratigraphic terminology that could be applied to repeatedly collapsing stratovolcanoes elsewhere.  相似文献   

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