The British Palaeogene Volcanic Province - Ailsa Craig Geological Conservation Review site     

C.G. Smith  R.M.L. Wignall 《Proceedings of the Geologists' Association. Geologists' Association》2021,132(1):16-23

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Absence of regional stratigraphic hiatus in the late Carboniferous (Asturian - Stephanian) in the northern Variscan foreland: a review of the bio- and lithostratigraphical evidence in central england     

B.M. Besly  C.J. Cleal 《Proceedings of the Geologists' Association. Geologists' Association》2021,132(1):50-65

An extensive regional stratigraphic hiatus has been proposed in the Asturian to Stephanian foreland basin successions lying to the north of the main Variscan deformation belt, stretching from north west Europe to eastern North America. The hiatus is inferred on megafloral grounds and involves the absence of most if not all of Stephanian Substages B and C. If present it would have great significance for the understanding of regional basin dynamics in the later stages of the Variscan orogeny. However, its existence has been strongly contested. One of the keys to this hypothesis is the correct identification and interpretation of plant fossils from the Warwickshire Coalfield (Central England). The published identifications are here shown to be incorrect, and revised determinations taken in conjunction with other stratigraphic data from Central England suggest that a regional hiatus is not present in the early-mid Stephanian, and that any stratigraphic hiatuses at other horizons in the succession are of purely local extent. A review of known occurrences of the Asturian and Stephanian successions in basins stretching from eastern Canada to Germany suggests that, while facies developments may be similar, there is little uniformity in stratigraphic style and little evidence for a major Stephanian hiatus.  相似文献   

尼泊尔低喜马拉雅推覆带油源对比及油气成藏     

杨平  谭富文  施美凤  王正和  李忠雄  占王忠  Sudhir RAJAURE  Ganesh N.TRIPATHI 《地质学报》2021,95(11):3426-3441

尼泊尔低喜马拉雅推覆带油气苗来源不清极大地影响了该区油气勘探.在地质-地球物理综合调查的基础上,利用油气地球化学、碳同位素及生烃史模拟对尼泊尔代莱克地区油源和成藏过程进行了研究.结果表明:①尼泊尔代莱克地区油苗产于Padukasthan断裂,可分两期,第一期呈含油断层泥产出,氯仿沥青"A"为149～231 μg/g,RR.为0.81％,氯仿沥青"A"的δ13C相对较重(-26.24‰～-27.10‰),族组分具有正碳同位素序列,发黄绿色荧光,为典型的低熟煤成油,第二期呈液态油产出并遭受微生物降解,金刚烷IMD指数为0.33～0.45,R.为1.24％～1.53％,3,4-DMD含量46％～47％,全油δ13C为-29.50‰～-29.45‰,族组分碳同位素趋于一致,发蓝色荧光,为海相成因高熟油;②第一期油来源于Surkhet群的Melpani组和Gondwana群煤系烃源岩,为Ⅲ型有机质低熟阶段的产物,第二期来源于Surkhet群的Swat组浅海陆棚相黑色页岩,为Ⅱ1型有机质生油高峰的产物,两期油与Lakharpata群过成熟黑色泥岩和Siwalik群未熟泥岩没有亲缘关系;③尼泊尔低喜马拉雅推覆带具有"多源多期、推覆增熟、砂体控储、披覆控聚"的油气成藏模式,油气成藏过程可划分为沉积浅埋、构造圈闭形成、深埋油藏形成、气藏形成和晚期改造定型5个演化阶段;④尼泊尔低喜马拉雅推覆有利于Gondwana群、Surkhet群深埋增温、持续快速生烃和晚期成藏,对比邻区巴基斯坦的含油气盆地,尼泊尔低喜马拉雅推覆带及相邻类似地区具备良好的油气成藏条件.  相似文献   

Louis Leakey and Piltdown Man     

S. Kenneth Donovan 《Proceedings of the Geologists' Association. Geologists' Association》2021,132(3):405-406

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Trend Analysis of Polynomial Surfaces and Surface Dynamics (TAPS‒SDs): A Paradigm from (MMT‒NPHMZ) in the Northwestern Himalayas,Pakistan     

Kaukab  I. S.  Batool  S.  Mahmood  S. A. 《Geotectonics》2021,55(2):273-292

Geotectonics - Generation and interpretation of geomorphometric maps through remote sensing and GIS techniques are significant platforms for the investigations of neotectonics. This investigation...  相似文献   

Granitoid Massifs of the Krasnoleninsky Arch in Western Siberia: Composition,Structure, Age,and Formation Conditions     

Khotylev  A. O.  Mayorov  A. A.  Khudoley  A. K.  Ershova  V. B.  Kalmykov  G. A.  Khubanov  V. B.  Chervyakovskaya  M. V. 《Geotectonics》2021,55(2):219-239

Geotectonics - In our research we summarized data obtained on the composition, structure, and geochemical characteristics of the granitoid plutons of the eastern part of the Krasnoleninsky arch of...  相似文献   

Modeling and Simulating Ground Motion from Potential Seismic Sources to Kuwait: Local and Regional Scenarios     

Abd el-aal  A. K.  Parol  J.  Al-Jeri  F.  Al-Enezi  A. 《Geotectonics》2021,55(3):423-438

Geotectonics - The urban development in Kuwait is growing rapidly in the past few years. Recently, a large number of new bridges, tall buildings and other infrastructures are constructed in Kuwait....  相似文献   

Relationship between Strong Earthquakes and Activation of Deep Faults in Central Asia (Uzbekistan): Numerical Simulation of Stress Field Variations     

Atabekov  I. U.  Artikov  T. U.  Ibragimov  R. S.  Ibragimova  T. L.  Mirzaev  M. A. 《Geotectonics》2021,55(3):377-392

Geotectonics - The results of analyzing the data on strong М ≥ 5 earthquakes in Central Asia for 1901–2013 are presented. A statistical method for studying the influence of the...  相似文献   

Late Pleistocene baldcypress (Taxodium distichum) forest deposit on the continental shelf of the northern Gulf of Mexico     

Kristine L. Delong  Suyapa Gonzalez  Jeffrey B. Obelcz  Jonathan T. Truong  Samuel J. Bentley Sr  Kehui Xu  Carl A. Reese  Grant L. Harley  Alicia Caporaso  Zhixiong Shen  Beth A. Middleton 《Boreas: An International Journal of Quaternary Research》2021,50(3):871-892

Approximately 13 km south of Gulf Shores, Alabama (United States), divers found in situ baldcypress (Taxodium distichum) stumps 18 m below the ocean surface. These trees could have only lived when sea level fell during the Pleistocene subaerially exposing the tectonically stable continental shelf. Here we investigate the geophysical properties along with microfossil and stratigraphical analyses of sediment cores to understand the factors that lead to this wood’s preservation. The stumps are exposed in an elongated depression (~100 m long, ~1 m deep) nested in a trough of the northwest–southeast trending Holocene sand ridges and troughs with 2–5 m vertical relief and ~0.5 km wavelength. Radiocarbon ages of the wood were infinite thus optically stimulated luminescence (OSL) dating was used to constrain the site’s age. Below the Holocene sands (~0.1–4 m thick), separated by a regional erosional unconformity, are Late Pleistocene mud-peat (72±8 ka OSL), mud-sand (63±5, 73±6 ka OSL), and palaeosol (56±5 ka OSL) facies that grade laterally from west to east, respectively. Foraminiferal analysis reveals the location of the terrestrial-marine transitional layer above the Pleistocene facies in an interbedded sand and mud facies (3940±30 (1σ) ¹⁴C a BP), which is part of a lower shoreface or marine-dominated estuarine environment. The occurrence of palaeosol and swamp facies of broadly similar ages and elevation suggests the glacial landscape possessed topographic relief that allowed wood, mud and peats to be preserved for ~50 ka of subaerial exposure before transitioning to the modern marine environment. We hypothesize that rapid sea-level rise occurring ~60 or ~40 ka ago provided opportunities for local flood-plain aggradation to bury the swamp thus preserving the stumps and that other sites may exist in the northern Gulf of Mexico shelf.  相似文献   

9000 years of changes in peat organic matter composition in Store Mosse (Sweden) traced using FTIR-ATR     

Antonio Martínez Cortizas  Jenny K. Sjöström  Eleonor E. Ryberg  Malin E. Kylander  Joeri Kaal  Olalla López-Costas  Noemi Álvarez Fernández  Richard Bindler 《Boreas: An International Journal of Quaternary Research》2021,50(4):1161-1178

Store Mosse (the ‘Great Bog’ in Swedish) is one of the most extensive bog complexes in southern Sweden (~77 km²), where pioneering palaeoenvironmental research has been carried out since the early 20th century. This includes, for example, vegetation changes, carbon and nitrogen dynamics, peat decomposition, atmospheric metal pollution, mineral dust deposition, dendrochronology, and tephrochronology. Even though organic matter (OM) represents the bulk of the peat mass and its compositional change has the potential to provide crucial ecological information on bog responses to environmental factors, peat OM molecular composition has not been addressed in detail. Here, a 568-cm-deep peat sequence was studied at high resolution, by attenuated reflectance Fourier-transform infrared spectroscopy (FTIR-ATR) in the mid-infrared region (4000–400 cm^–1). Principal components analysis was performed on selected absorbances and change-point modelling was applied to the records to determine the timing of changes. Four components accounted for peat composition: (i) depletion/accumulation of labile (i.e. carbohydrates) and recalcitrant (i.e. lignin and other aromatics, aliphatics, organic acids and some N compounds) compounds, due to peat decomposition; (ii) variations in N compounds and carbohydrates; (iii) residual variation of lignin and organic acids; and (iv) residual variation of aliphatic structures. Peat decomposition showed two main patterns: a long-term trend highly correlated to peat age (r = 0.87), and a short-term trend, which showed five main phases of increased decomposition (at ~8.4–8.1, ~7.0–5.6, ~3.5–3.1, ~2.7–2.1 and ~1.6–1.3 ka) – mostly corresponding to drier climate and its effect on bog hydrology. The high peat accumulation event (~5.6–3.9 ka), described in earlier studies, is characterized by the lowest degree of peat decomposition of the whole record. Given that FTIR-ATR is a quick, non-destructive, cost-effective technique, our results indicate that it can be applied in a systematic way (including multicore studies) to peat research and provide relevant information on the evolution of peatlands.  相似文献