Potential application of biogenic silica as an indicator of paleo-primary productivity in East Antarctic lakes     

JIANG Shan  LIU XiaoDong  XU LiQiang  SUN LiGuang 《极地研究(英文版)》2011,(3):131-142

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Distribution characteristics,exploration and development,geological theories research progress and exploration directions of shale gas in China     

Shi-zhen Li  Zhi Zhou  Hai-kuan Nie  Lei-fu Zhang  Teng Song  Wei-bin Liu  Hao-han Li  Qiu-chen Xu  Si-yu Wei  Shu Tao 《China Geology》2022,5(1):110-135

The shale gas resources in China have great potential and the geological resources of shale gas is over 100×10¹²m³,which includes about 20×10¹²m³ of recoverable resources.Organic-rich shales can be divided into three types according to their sedimentary environments,namely marine,marine-continental transitional,and continental shales,which are distributed in 13 stratigraphic systems from the Mesoproterozoic to the Cenozoic.The Sichuan Basin and its surrounding areas have the highest geological resources of shale gas,and the commercial development of shale gas has been achieved in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in these areas,with a shale gas production of up to 20×10⁹m³ in 2020.China has seen rapid shale gas exploration and development over the last five years,successively achieving breakthroughs and important findings in many areas and strata.The details are as follows.(1)Large-scale development of middle-shallow shale gas(burial depth:less than 3500 m)has been realized,with the productivity having rapidly increased;(2)breakthroughs have been constantly made in the development of deep shale gas(burial depth:3500-4500 m),and the ultradeep shale gas(burial depth:greater than 4500 m)is under testing;(3)breakthroughs have been made in the development of normal-pressure shale gas,and the assessment of the shale gas in complex tectonic areas is being accelerated;(4)shale gas has been frequently discovered in new areas and new strata,exhibiting a great prospect.Based on the exploration and development practice,three aspects of consensus have been gradually reached on the research progress in the geological theories of shale gas achieved in China.(1)in terms of deep-water fine-grained sediments,organic-rich shales are the base for the formation of shale gas;(2)in terms of high-quality reservoirs,the development of micro-nano organic matter-hosted pores serves as the core of shale gas accumulation;(3)in terms of preservation conditions,weak structural transformation,a moderate degree of thermal evolution,and a high pressure coefficient are the key to shale gas enrichment.As a type of important low-carbon fossil energy,shale gas will play an increasingly important role in achieving the strategic goals of peak carbon dioxide emissions and carbon neutrality.Based on the in-depth study of shale gas geological conditions and current exploration progress,three important directions for shale gas exploration in China in the next five years are put forward.  相似文献   

Burial and infilling of a karst in Papua New Guinea by road erosion sediments     

J. M. James 《Environmental Geology》1993,21(3):144-151

The anthropogenic impact on karst in Papua New Guinea is briefly introduced and a specific case is presented detailing the effect of road erosion sediments on a small karst. The karst is in the perennially humid tropics and covered with primary rain forest. The road was placed high above the karst on steep friable rock and traverses several of its catchments. The changes to and the rate of burial of parts of the karst and the infilling of the caves are described. The karst drainage has altered, and there is increased water storage. The sediment build-up ceased in less than a year due to vegetation and stabilization of the road embankments. It is concluded that any construction within a catchment leading to a karst should be assessed as to its impact on the karst.  相似文献   

Investigating contemporary and historical sediment inputs to Slapton Higher Ley: an analysis of the robustness of source ascription methods when applied to lake sediment data     

N. Jenns  C. M. Heppell  T. P. Burt  J. Walden  I. D. L. Foster 《水文研究》2002,16(17):3467-3486

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Terraced fills of Pleistocene and Holocene age in the Rheidol Valley,Wales     

Mark G. Macklin  John Lewin 《第四纪科学杂志》1986,1(1):21-34

The legacy of repeated Pleistocene glaciations has endowed many Welsh river valleys with locally thick successions of glacial and alluvial sediments. Investigations of a well-preserved flight of terraced sediments with good exposures at Capel Bangor, on the Afon Rheidol, mid-Wales, has allowed its Quaternary valley fill stratigraphy to be examined in detail. Study has revealed five terraced fills consisting of seven distinct sedimentary units. These range from Late Devensian ice-contact and ice-marginal deposits, to Holocene high-sinuosity stream sediments with episodes of man-induced accelerated deposition of fine-grained alluvium, and to aggradation and subsequent incision associated with historic metal mining. Examination of general sedimentary properties (e.g., granulometry, sedimentary structures, terrace surface morphology) show both differences in the pattern and controls of deposition and also progressive changes over Late Devensian and Holocene times. The sediments of the Rheidol Valley record the response and subsequent recovery of a drainage basin to glaciation, and the increasing influence of man on sediment yields, channel processes, and sediment quality.  相似文献   

Decadal to millennial cyclicity in varves and turbidites from the Arabian Sea: hypothesis of tidal origin   总被引：1，自引：0，他引：1  

W. H. Berger  U. von Rad 《Global and Planetary Change》2002,34(3-4)

We have analyzed a Late Holocene record, almost 5000 years long, consisting of varved sediments deposited in the oxygen-minimum zone (OMZ) off Pakistan. We searched for cyclicity in the series of varve thickness (“varve” cycles), of unusually large excursions in varve thickness (“agitation” cycles), and of abundance of turbidites (“turbidite” cycles). We found the following high-frequency cycles (periods between 10 and 100 years) in one or several of the three types of series as follows: near 12.4, 14–15, 16.8, 18.6 (strong, agitation), 25–26 (strong, turbidite), 29–31 (strong, agitation), 39 (varve), 44 (strong, turbidite), 51–54 (strong, agitation), 56 (strong, varve), 64 (strong, turbidite), 69, 77 (strong, turbidite), 82 (very strong, agitation), and 95 years (strong, varve). Low-frequency cycles center around 99–115, 125 (very strong, varve), 164, 177, 202, 242–255 (strong, agitation and turbidite), 280 (strong, varve; doubled, turbidite), 340–370 and 460–490 years.Some cycles of varve thickness match the cyclicity of turbidite frequency (12.3, 14–15, 25–26, 245–255 years) but similarities between spectra are not striking. Taken as a whole, however, the sequence of cycles detected (by autocorrelation and standard Fourier analysis) seems to contain a large proportion of multiples of the basic tidal cycles 4.425 (lunar perigee cycle) and 9.3 years (lunar half-nodal cycle). This impression is supported by testing the three binned spectra for whole-number multiples and fractions as well as whole-number beat structure. We therefore propose that a large proportion of the cyclicity detected can be ascribed to tidal action. Our record also contains evidence for the presence of the 1470-year cycle previously reported from the glacial-age Greenland ice record. The main harmonics of this Greenland cycle can be tied to the pattern of periods seen in the varved sediments. We hypothesize that tidal action produces the cycle, and that the reason for its great length is the requirement that maximum tidal activity has to fall into a narrow seasonal window to be geologically effective.  相似文献   

The HON-Kajak sediment corer   总被引：17，自引：10，他引：7  

Ingemar Renberg 《Journal of Paleolimnology》1991,6(2):167-170

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RIVERINE SEDIMENTS AND CHINESE COASTLINE CHANGES     

李从先  张桂甲 《中国地理科学(英文版)》1997,7(3):201-207

I.TI~IC~~RIWiRIrmssoITheupliftingoftheQiughal--Xoing(Tibet)PIateaugeneratedlargeandsediment--ladenrivers,thusthenorthernindianOceanandthewesternPacificOceanreceivedlargevolumeofriverinesedimentswhichconstituteabbothalfofthetotalbinesedimentsintheworld.ChineseoutlinecrossesbobtectonicupliftbeltsandtectonicdepressionbeltS.RiverssuchastheHuanghe(Yellow)myerandChangjiang(Yangtze)caver,etc.~nglargevolumeofSedimentsadnlyrunintOtheseaatthetectonicdepreSSionbelts,andriverssuchastheZhujiang(…  相似文献   

The distribution and geochemistry of some trace metals in the Bermuda coastal environment     

T.D. Jickells  A.H. Knap 《Estuarine, Coastal and Shelf Science》1984,18(3):245-262

Results of the analyses of the water column and sediments of the Bermuda Platform for Cd, Cu, Fe, Mn, Ni, Pb and Zn are presented. The major process controlling the water column concentrations is physical mixing of open ocean waters with inshore waters, which are polluted by a wide range of diffuse inputs. Sedimentation within the inshore waters plays a lesser, but significant, role as do fluxes from the sediments of Fe and Mn and possibly phytoplankton uptake of Zn. Concentrations within the sediments are controlled by the formation of trace metal enriched clay/organic particles in the inshore areas and their subsequent redistribution by sediment resuspension, except for Fe and Mn which are largely associated with clay lattices.  相似文献   

Desorption of ¹⁰⁶Ru, ¹³⁴Cs, ¹³⁷Cs, ¹⁴⁴Ce and ²⁴¹Am from intertidal sediment contaminated by nuclear fuel reprocessing effluents     

D.A. Stanners  S.R. Aston 《Estuarine, Coastal and Shelf Science》1982,14(6):687-691

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