首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 171 毫秒
1.
We explore the hypothesis that the abrupt drainage of Laurentide lakes and associated rapid switch of the North Atlantic thermohaline circulation 8200 yr ago had a catastrophic influence on Neolithic civilisation in large parts of southeastern Europe, Anatolia, Cyprus, and the Near East. The event at 8200 cal yr BP is observed in a large number of high-resolution climate proxies in the Northern Hemisphere, and in many cases corresponds to markedly cold and arid conditions. We identify the relevant archaeological levels of major Neolithic settlements in Central Anatolia, Cyprus, Greece and Bulgaria, and examine published stratigraphic, architectural, cultural and geoarchaeological studies for these sites. The specific archaeological events and processes we observe at a number of these sites during the study interval 8400–8000 cal yr BP lead us to refine some previously established Neolithisation models. The introduction of farming to South-East Europe occurs in all study regions (Thrace, Macedonia, Thessaly, Bulgaria) near 8200 cal yr BP. We observe major disruptions of Neolithic cultures in the Levant, North Syria, South-East Anatolia, Central Anatolia and Cyprus, at the same time. We conclude that the 8200 cal yr BP aridity event triggered the spread of early farmers, by different routes, out of West Asia and the Near East into Greece and Bulgaria.  相似文献   

2.
研究目的】在末次冰期,全球气候变化以千年尺度的快速、大幅度温度波动旋回为特征,这种波动变化在两极冰芯、深海沉积、中国黄土和洞穴石笋等诸多地质样品中均有记录。黑海位于北大西洋与东亚季风区过渡带,具有极有代表性的沉积记录。本文旨在通过对黑海沉积序列的研究,建立起其区域环境变化与北大西洋及东亚季风气候域气候变化的联系。【研究方法】研究对取自黑海西北部罗马尼亚陆坡区多瑙河峡谷北侧GAS-CS12钻孔的长22.0 m的岩芯样品,进行了粒度、矿物成分、主量元素、有机碳、总氮及碳氮同位素等分析。【研究结果】揭示出该段岩芯沉积于末次冰期中后期“Neoeuxine”湖相阶段,可划分为5个沉积单元,对应于北大西洋H4、H3、H1气候变化事件、末次冰盛期(LGM)及Bolling-Allerod气候变暖事件。【结论】建立起了其沉积序列及区域环境变化与北大西洋及东亚季风气候域气候变化的联系,印证了末次冰期千年尺度的气候变化事件在北大西洋、东亚季风区及两者过渡带上具有高度的一致性。创新点:建立了黑海西北沉积序列与区域环境变化的关系;补充了北大西洋与东亚季风区两者过渡带上气候波动事件的可靠时标。  相似文献   

3.
A major environmental and societal event struck the Mediterranean basin during the 9th millennium cal BP. A sudden and major climatic crisis occurred in the Northern Hemisphere around 8200 cal BP leading to hyper arid conditions along a tropical zone between 15° and 40° North (Near and Middle East), cooler and wetter conditions in western and central Europe, and marked climatic irregularity in the northern Mediterranean basin. At the same time, frequent cultural gaps are observed in cave infillings from Greece to the Spanish peninsula between 8500 and 8000 cal BP, making the vision of the European Mesolithic–Neolithic transition more complex. Furthermore, a stratigraphic and socio-economic rupture associated with a spatial redistribution of sites characterizes the PPNB-NC/Yarmoukian transition in the Near East. The impact of these climatic and environmental changes in the first centuries of the neolithisation of Mediterranean Europe is discussed, using the socio-cultural, economic, stratigraphic and chronological evidence for the first farmers and last hunter-gatherers. This evidence is compared to recent paleoclimatic and geo-archaeological data obtained from prehistoric contexts, in order to measure the hydro-morphological impact on activities in valleys and karstic rockshelters.  相似文献   

4.
Divya P. Tolia-Kelly   《Geoforum》2004,35(6):675-688
This paper considers the role of visual cultures in understanding the value of landscape to post-colonial migrants living in Britain. The paper also considers these visual cultures as prismatic devices which refract lived landscapes of South Asia and East Africa into British domestic scene. The visual cultures are investigated using a materialist lens. They are positioned as materials that allow embodied connections to landscapes experienced pre-migration, including sensory connections with past homes, natures and family life. These then become artefacts symbolising relationships with past landscapes, made meaningful in their presence in Britain homes. Using this materialist lens, visual cultures in the British Asian home, such as photographs, pictures, and paintings, are given meaning and value beyond their textual content. This paper is an exercise in reading visual cultures in the everyday through a materialist lens which allows for an examination of their place in the process of ‘making home' for South Asian women in Britain. In particular, objects presence the migratory experience of the South Asian community, importing ‘other' landscapes (previously shaped by colonial governance) into Britain, and help to shape environmental values, landscape imaginaries and South Asian landscapes of belonging in the post-colonial period.  相似文献   

5.
Until recently the world economy was focused on four core areas: in western Europe, North America, the Soviet Union, and Japan. Beyond them was the periphery. The economic growth of the periphery depended on core-periphery trade. Since the existing core areas were too few to absorb the periphery's potential production, much of the periphery was producing below capacity. Currently more core areas are coming into existence in Brazil, South Korea, and India. They promote economic development by enlarging the market for peripheral products, drawing resources from the remaining periphery, and providing competition to existing core areas. Latent potentials for core area growth exist in the Near East and southern Africa, but their realization presumes political settlements. The west European core area has expanded onto the Iberian Peninsula and may expand soon beyond the erstwhile Iron Curtain.  相似文献   

6.
The first unequivocal remains of medium to large-sized mustelids from the middle Miocene Halamagai and Kekemaideng formations have been found in the Ulungur River area, Xinjiang, northwestern China. These new fossils are referred to the hypercarnivorous mustelid Hoplictis Ginsburg, 1961 and denote the first record of the genus in East Asia.We define Hoplictis baihu n. sp., for the mustelid from Tieersihabahe(Halamagai Fm.), which represents the smallest species of the genus. This primitive form is closer to H. florancei and H. noueli than to H. anatolicus and later, larger and more derived Hoplictis spp., from Europe and North America. A large toothless mandible from Duolebulejin(Kekemaiden Fm.) is assigned to Hoplictis cf. helbingi, and it presumably might represent the first record of H. helbingi outside Western Europe. The systematic position of Hoplicitis in relation to Ischyrictis with which it is similar is clarified. The occurrence in East Asia of two species of Hoplictis greatly expands the known distribution and diversity of the genus, and supports a Palaearctic Neogene dispersal event of carnivorans between Europe and Asia during the late Shanwangian–early Tunggurian equivalent to MN5–6 in Europe, and indication of another dispersal event from Europe to North America,through Northwest China during the late Tunggurian, equivalent to MN7–8 in Europe.  相似文献   

7.
The early stages of agriculture in the Boreal forests of Northern Europe remain poorly understood. Although pottery appeared during the 6th millennium B.C., this has not been seen as an indication of a true Neolithic in the north. In later prehistory, vast parts of the region are thought to have remained a wilderness. In order to test these assumptions, a high‐resolution pollen analysis and an archaeological survey were carried out at Lake Huhdasjärvi, SE Finland. The results indicate signs of cultivation already by the early Neolithic, 5260–4260 B.C., and slash‐and‐burn cultivation concentrated on deciduous forests is recorded from ca. A.D. 600 onwards. By A.D. 930, an intensive form of swidden cultivation began in the coniferous forests, indicating a well‐established agricultural settlement. The discovery of Neolithic (late 6th millennium B.C.) buckwheat pollen suggests that the roots of agriculture in northernmost Europe may have to be searched for in China rather than the Near East.  相似文献   

8.
Supergene manganese deposits commonly contain K-rich Mn oxides with tunnel structure, such as cryptomelane, which are suitable for radiometric dating using the 39Ar–40Ar method. In Africa, Mn deposits have been dated by this method for localities in western and southern parts of the continent, whereas only some preliminary data are available for Central Africa. Here we present new 39Ar–40Ar ages for Mn oxide samples of the Kisenge deposit, in southwestern Katanga, Democratic Republic of the Congo. The samples represent supergene Mn oxide deposits that formed at the expense of primary Paleoproterozoic rhodochrosite-dominated carbonate ores. Main phases of Mn oxide formation are dated at c. 10.5 Ma, 3.6 Ma and 2.6 Ma for a core that crosses a mineralized interval. The latter shows a decrease in age with increasing depth, recording downward penetration of a weathering front. Surface samples of the Kisenge deposits also record a ≥ c.19.2 Ma phase, as well as c. 15.7 Ma, 14.2 Ma and 13.6 Ma phases. The obtained ages correspond to distinct periods of paleosurface development and stability during the Mio-Pliocene in Katanga. Because Katanga is a key area bordered to the North by the Congo Basin and to the East by the East African Rift System, these ages also provide constraints for the geodynamic evolution of the entire region. For the Mio-Pliocene, the Kisenge deposits record ages that are not systematically found elsewhere in Africa, although the 10.5–11 Ma event corresponds to a roughly simultaneous event in the Kalahari Manganese Field, South Africa. The rest of the Katanga paleosurface record differs somewhat from records for other parts of Africa, for which older, Eocene ages have been obtained. This difference is most probably related to the specific regional geodynamic context: uplift of the East African Plateau, with associated erosion, and the opening of the East African Rift System at c. 25 Ma are events whose effects, in the study area, interfere with those of processes responsible for the development of continent-wide paleosurfaces.  相似文献   

9.
The Nubia Sandstone aquifer system is one of the most extensive groundwater systems in North Africa, covering an area of about 2,000,000 km2, including parts of Egypt, Libya, Sudan, and Chad. In the Western Desert of Egypt, the Nubian formation has a thermal gradient of 1.1–5°C 100 m–1 with the exception of the East Oweinat area, located in the southern part of the Western Desert. This is the only part of this huge system where ground-water occurs under unconfmed conditions in an area where the Nubian sandstone crops out and is underlain by shallow basement rocks; in this area groundwater has no thermal characteristics. The aquifer system in the East Oweinat area attains a relatively high hydraulic conductivity. The direction of groundwater flow is generally northeastwards but is distorted at faults and fracture zones. Chemical analyses of groundwater in the area indicate a low salt content and suitability for irrigation purposes. As the estimated recharge to the area is low compared with the foreseen irrigation water requirement, the development of groundwater in the East Oweinat should be based on groundwater mining. Although the evaluation of the groundwater resources in East Oweinat has indicated that groundwater can be extracted at a rate of 4.7×106 m3 d–1, the long-term economics of extraction that can sustain large-scale development projects has to be assessed.  相似文献   

10.
Late Pleistocene variations in rainfall in subtropical southern African are estimated from sediments preserved in the Pretoria Saltpan, a 200000 year-old closed-basin crater lake on the interior plateau of South Africa. We show that South African summer rainfall covaried with changes in southern hemisphere summer insolation resulting from orbital precession. As predicted by orbital precession geometry (Berger, 1978), this South African record is out of phase with North African palaeomonsoon indices (Street and Grove, 1979; Rossignol-Strick, 1983; McIntyre et al., 1989); the amplitude of the rainfall response to insolation forcing agrees with climate model estimates (Prell and Kutzbach, 1987). These results document the importance of direct orbital insolation forcing on both subtropical North and South African climate as well as the predicted antiphase sensitivity to precessional insolation forcing.  相似文献   

11.
Orthophragminids from the Bartonian Fulra Limestone in Kutch, India and the coeval units in Sulaiman Range in Pakistan suggest the establishment of a significant number of endemic species in the Indian subcontinent (Eastern Tethys). Among a total of fifteen species of Discocyclina, Orbitoclypeus and Asterocyclina, six of them appear to be confined to Indian subcontinent while seven species are common both to the peri-Mediterranean/Europe region (Western Tethys) and Indian subcontinent. Two species, Asterocyclina sireli, a four-ribbed species of possibly Indo-Pacific origin, and Orbitoclypeus haynesi that form large populations in Fulra Limestone, appear to have spread into North Africa and Turkey but not into European platforms as a response to Middle Eocene Climatic Optimum (MECO). The lack of Lutetian and Priabonian fauna in the studied sections, either due to a hiatus or unsuitable depositional environments, hampers the establishment of the actual stratigraphic ranges of the identified taxa. Our record provides us to characterize the orthophragminids in shallow benthic zone (SBZ) 17 for Eastern Tethys in detail by comparing the data from the above localities with those from the North Africa, Europe and Turkey, showing the change in diversity.  相似文献   

12.
寒武纪三叶虫生物地理区的一些问题   总被引:1,自引:0,他引:1  
张文堂 《地学前缘》2006,13(6):139-144
文内叙述寒武纪三叶虫分类、分布和分区。世界上有两个寒武纪生物地理区,一个是北区,另一个是南区。斜坡带的球接子类及少数多节类是世界性分布的,仅能视作任何一区内的生态小区。两区的分界在北非的北部、土耳其的南部,再向东连接天山的北部边缘及蒙古的南部边缘。从南欧寒武纪三叶虫的情况看,是海水深度频繁变化的结果。中国任何一个地区,既不属东冈瓦纳,也不属西冈瓦纳。  相似文献   

13.
Aeromagnetic surveys help reveal the geometry of Precambrian terranes through extending the mapping of structures and lithologies from well-exposed areas into areas of younger cover. Continent-wide aeromagnetic compilations therefore help extend geological mapping beyond the scale of a single country and, in turn, help link regional geology with processes of global tectonics. In Africa, India and related smaller fragments of Gondwana, the margins of Precambrian crustal blocks that have escaped (or successfully resisted) fracture or extension in Phanerozoic time can often be identified from their aeromagnetic expression. We differentiate between these rigid pieces of Precambrian crust and the intervening lithosphere that has been subjected to deformation (usually a combination of extension and strike-slip) in one or more of three rifting episodes affecting Africa during the Phanerozoic: Karoo, Early Cretaceous and (post-) Miocene. Modest relative movements between adjacent fragments in the African mosaic, commensurate with the observed rifting and transcurrent faulting, lead to small adjustments in the position of sub-Saharan Africa with respect to North Africa and Arabia. The tight reassembly of Precambrian sub-Saharan Africa with Madagascar, India, Sri Lanka and Antarctica (see animation in http://kartoweb.itc.nl/gondwana) can then be extended north between NW India and Somalia once the Early Cretaceous movements in North Africa have been undone. The Seychelles and smaller continental fragments that stayed with India may be accommodated north of Madagascar. The reassembly includes an attempt to undo strike-slip on the Southern Trans-Africa Shear System. This cryptic tectonic transcontinental corridor, which first formed as a Pan-African shear belt 700–500 Ma, also displays demonstrable dextral and sinistral movement between 300 and 200 Ma, not only evident in the alignment of the unsuccessful Karoo rifts now mapped from Tanzania to Namibia but also having an effect on many of the eventually successful rifts between Africa-Arabia and East Gondwana. We postulate its continuation into the Tethys Ocean as a major transform or megashear, allowing minor independence of movements between West Gondwana (partnered across the Tethys Ocean with Europe) and East Gondwana (partnered with Asia), Europe and Asia being independent before the 250 Ma consolidation of the Urals suture. The relative importance of primary driving forces, such as subduction ‘pull’, and ‘jostling’ forces experienced between adjacent rigid fragments could be related to plate size, the larger plates being relatively closely-coupled to the convecting mantle in the global scheme while the smaller ones may experience a preponderance of ‘jostling’ forces from their rigid neighbours.  相似文献   

14.
1 Introduction The stromatolites of the Jiawengmen area in the southern belt of the Eastern Kunlun orogen were initially interpreted as vortex structures by the Regional Geological Survey Team, Qinghai Bureau of Geology and Mineral Resources in 1973; these samples were then identified as algal fossils of Sinian age by the Nanjing Institute of Geology and Paleontology (Qinghai Bureau of Geology and Mineral Resources, 1973). In 1994, Chen and Luo (1998) discovered some stromatolites, i…  相似文献   

15.
Marine sediment location spread over a wide range of environments contain evidence of anoxic intervals dated early Late Cretaceous. In the north and south deep Atlantic deposition of anoxic layers followed a widespread sedimentary hiatus of Middle Cenomanian age. In the eastern-central parts of the Atlantic (Angola and Cape Verde basins) rythmic deposition of anoxic layers commenced in the Latermost Cenomanian and lasted as late as the Santonian. In the rest of the deep north Atlantic on the contrary anoxia duration was probably limited to the Cenomanian-Turonian boundary or thereabout. Late Cretaceous anoxic layer is not yet recorded south of the Walvis-Rio Grande Rises in the South Atlantic. In a number of locations in marginal and epicontinental seas in America, Africa and Europe previously related to the Tethys a few anoxic layers dated Cenomanian-Turonian are intercalated within thick oxic series. Coniacian to Santonian anoxic layers are limited to small areas in epeiric and marginal domains in the southern Alps, North Africa, Israel, North America (Santonian in the Western Interior) and (?) Australia all with no clear link with any ocean-wide event of early Senonian age. Rythmical alternation of oxic/anoxic layers helps to document the emplacement of sediment and disposition of anaerobic water masses. Development of anoxia at about the Cenomanian-Turonian boundary induced abnormal concentration of trace metals and a partial renewal of the marine fauna. To understand the relationship between a number of factors such as sea-level changes, climates, terrestrial influences, biogenic fertility, sedimentation rates, etc., is essential to explain of the very peculiar anoxic global event of early Late Cretaceous age.  相似文献   

16.
Southeast Europe has historically been at the crossroads of migration routes between Western Asia and Europe. In the Holocene, this area might have been home to malaria. However, it is questionable when malaria arrived in this area and whether it could persist continuously or not in the Holocene. To begin to answer these questions, the July potential generation number of two malaria parasites were modelled, based on the reconstructed mean July temperatures of 52 times in the last 27 000 years. The results indicate that in the late Pleistocene era (27–12 kya bp ), vivax malaria might have been present in the south-east Black Sea and Aegean Sea's coastal areas. Vivax malaria could also be present in the Pannonian Basin and the inner parts of the North Balkans at least from the mid-Greenlandian period (~10 kya bp ). Although it is questionable whether falciparum malaria could be endemic in the Pannonian Basin during the mid-Holocene climate optimum (~6 kya bp ), this malaria plausibly could be endemic from the Neolithic era (~12–6.5 kya bp ) in the major river valleys of the North Balkan region, millennia ahead of the Graeco-Roman times (8th century bce to 6th century ce ).  相似文献   

17.
A series of discontinuous sediment sequences, of Plio/Pleistocene age, occur onshore around the southern North Sea margins, notably in the East Anglian region of Britain. Intensive lithological and palaeontological analyses of these sediments have shown that they record both major and minor oscillations in climate, sea level and environmental conditions. However, significant uncertainties exist regarding the absolute and relative chronostratigraphies of many of these sequences, hindering understanding of the relative impacts of climatic, eustatic and tectonic changes on the palaeogeographic development of the southern North Sea basin. Here, a number of key East Anglian Plio/Pleistocene sites are subjected to robust palaeomagnetic and mineralogical examination, in order to determine those sediments which display reliable, syn‐depositional magnetic polarities, which are thus of use in ascribing a palaeomagnetically determined age from comparison with the Geomagnetic Polarity Timescale (GPTS). Based on a range of palaeomagnetic and complementary mineralogical methods, reliable palaeomagnetic directions were obtained from eight sites, with reversed polarities displayed by sediments from three sites. These polarity determinations can be used to infer absolute ages and test published, between‐site correlations. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

18.
We present a thorough review of the knowledge on the climate and environment in Sicily over the last 20 000 years, taking into account results of several studies carried using terrestrial and marine records. We obtain a coherent framework of the most important changes succeeded in the island, even if some points need further investigation. All the reconstructions of surface temperatures of the seas and the air surrounding Sicily point out severe climatic conditions during the last glacial period. The steppe- and semisteppe-like vegetation pattern testifies, together with additional evidence from geochemical data of lacustrine evidence, markedly arid conditions. Fi-nally, significant episodes of sea level drop connected Sicily to the Italian Peninsula and favoured the dispersion of faunal elements from southern Italy. The transition between the last glacial and the Holocene was not characterized by a gradual warming but was punctuated by two abrupt suborbital climatic fluctuations: Bølling-Allerød (warm) and Younger Dryas (cold), as recognized in the sediments recovered close to the northern and southern coast of Sicily. A denser arboreal cover is possibly indicated by the occurrence of dormouse and Arvicola remains. Finally the sensitivity of Sicily to climate perturbations is demonstrated by the occurrence of repeated subtle climatic anomalies during the Holocene, including the Little Ice Age, also known from historical chronicles. Forests, woods and Mediterranean maquis developed in the early-middle Holocene. Thereafter was a general decline of arboreal vegetation, following a general aridification trend that seems to be a common feature in southern Europe and North Africa. Science Greek colonization (7th century before Christ), the landscape was intensively modelled for agriculture and breeding, leading to a significant loss of vegetation cover.  相似文献   

19.
通过实地考察和对收藏标本的细致研究,以获取第一手资料的方式,文章客观地评价了中国古人类学研究者的工作业绩和历史局限,认为在中国发现的东亚早期人类的新证据为探讨人类起源的单极和多极理论提供了新的可能;东亚人的古老性是目前科研工作的关键问题,必须利用各种手段,对此予以尽可能准确的界定。与中国学者合作研究人字洞遗址、龙骨坡遗址和东谷坨遗址的结果说明中国的考古遗址具有多样性,各遗址的石器相互间差异性很大,与同一时期非洲的模式不同,在这里可以找到更加有趣的材料来认识早期人类的方方面面,因此,应以最严谨的态度和最高的注意力对待中国的考古发现。此外,结合中国古人类、旧石器遗址和古气候学的研究资料,文章从宏观地理学的角度阐述了旧石器时代阿舍利和勒瓦娄哇两个典型的文化现象及其发展脉络,探讨了旧石器时代东亚和西亚之间的关系,对中国旧石器文化的发展模式及其与西亚乃至全球的关系提出了个人的独到见解;着眼于研究早期工业技术的发现地、创新地及其传播地点等问题认为,中国同西欧一样,在地理环境和人类生存方面都处于孤立无援的境地,其技术的发展亲历了在本土发明、从境外引进和向外输出等不同阶段,它们不愧是穿越时空来追随技术变革的两大实验场。文章  相似文献   

20.
We discuss the question whether the late Mesoproterozoic and early Neoproterozoic rocks of eastern, central and southern Africa, Madagascar, southern India, Sri Lanka and South America have played any role in the formation and dispersal of the supercontinent Rodinia, believed to have existed between about 1000 and 750 Ma ago. First, there is little evidence for the production of significant volumes of ˜1.4–1.0 Ga (Kibaran or Grenvillian age) continental crust in the Mozambique belt (MB) of East Africa, except, perhaps, in parts of northern Mozambique. This is also valid for most terranes related to West Gondwana, which are made up of basement rocks older than Mesoproterozoic, reworked in the Brasiliano/Pan-African orogenic cycle. This crust cannot be conclusively related to either magmatic accretion processes on the active margin of Rodinia or continental collision leading to amalgamation of the supercontinent. So far, no 1.4–1.0 Ga rocks have been identified in Madagascar. Secondly, there is no conclusive evidence for a ˜1.0 Ga high-grade metamorphic event in the MB, although such metamorphism has been recorded in the presumed continuation of the MB in East Antarctica. In South America, even the Sunsas mobile belt, which is correlated with the Grenville belt of North America, does not include high-grade metamorphic rocks. All terranes with Mesoproterozoic ages seem to have evolved within extensional, aulacogen-type structures, and their compressional deformation, where observed, is normally much younger and is related to amalgamation of Gondwana. This is also valid for the Trans-Saharan and West Congo belts of West Africa.Third, there is also no evidence for post-1000 Ma sedimentary sequences that were deposited on the passive margin(s) of Rodinia. In contrast, the MB of East Africa and Madagascar is characterized by extensive structural reworking and metamorphic overprinting of Archaean rocks, particularly in Tanzania and Madagascar, and these rocks either constitute marginal parts of cratonic domains or represent crustal blocks (terranes or microcontinents?) of unknown derivation. This is also the case for most terranes included in the Borborema/Trans-Saharan belt of northeastern Brazil and west-central Africa, as well as those of the Central Goíás Massif in central Brazil and the Mantiqueira province of eastern and southeastern Brazil.Furthermore, there is evidence for extensive granitoid magmatism in the period ˜840 to <600 Ma whose predominant calc-alkaline chemistry suggests subduction-related active margin processes during the assembly of the supercontinent Gondwana. The location of the main Neoproterozoic magmatic arcs suggests that a large oceanic domain separated the core of Rodinia, namely Laurentia plus Amazonia, Baltica and West Africa, from several continental masses and fragments now in the southern hemisphere, such as the São Francisco/Congo, Kalahari and Rio de La Plata cratons, as well as the Borborema/Trans-Saharan, Central Goiás Massif and Paraná blocks. Moreover, many extensional tectonic events detected in the southern hemisphere continental masses, but also many radiometric ages of granitois that are already associated with the process of amalgamation of Gondwana, are comprised within the 800–1000 age interval. This seems incompatible with current views on the time of disintegration of Rodinia, assumed to have occurred at around 750 Ma.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号