收稿日期: 1999-08-30
修回日期: 2000-05-08
网络出版日期: 2000-12-01
基金资助
国家自然科学基金项目“吐哈盆地侏罗系储层地球化学研究”(编号:49773179);中国博士后科学基金项目“用TOF-SIMS分析矿物中单个有机包裹体成分”(编号:1999/10)和贵州省自然科学基金项目“黔西南三叠纪高分辨率层序地层的同位素地球化学响应(编号:99-3091)联合资助。
VARIATIONS OF RATIO OF87Sr/86Sr IN SEAWATER WITH TIME:IMPLICATIONS FOR SEA LEVEL CHANGES AND GLOBAL CORRELATION
Received date: 1999-08-30
Revised date: 2000-05-08
Online published: 2000-12-01
综述了近年来国际上在Sr同位素研究应用方面的新成果,着重讨论了如何应用海相沉积岩(物)87Sr/86Sr比值来研究海平面变化和全球对比问题。综合分析表明,海水Sr同位素组成受Sr的来源控制,海水87Sr/86Sr比值随时间变化与海平面变化有内在的联系,高频旋回(时限约2.0Ma)的87Sr/86Sr变化与三级海平面变化相对应。研究认为牙形石是分析Sr同位素组成最理想的样品,用之建立的87Sr/86Sr变化曲线最具全球对比意义。与国外相比,我国在这方面研究成果较少,但从地质条件分析,我国独有的一些地质记录,在古海平面变化和全球对比研究中占据着不可缺少或不可代替的地位,其中扬子地块西南缘二叠—三叠纪界限附近的87Sr/86Sr变化曲线,可以弥补国外一些学者建立的自显生宙以来全球海水87Sr/86Sr变化曲线在该时段存在的“断层”现象。
李荣西,魏家庸,杨卫东,郭庆军 . 用87Sr/86Sr研究海平面变化与全球对比问题[J]. 地球科学进展, 2000 , 15(6) : 729 -733 . DOI: 10.11867/j.issn.1001-8166.2000.06.0729
Strontium(Sr) is one of the most sensitive indicators to seawater. It has been widely exploited both in terms of its concentration and particularly in its isotope, which has been used to investigating ancient sea level fluctuations. Appreciable progresses have been achieved in recent years, but problems still remained with the seawater87Sr/86Sr curve construction for the purpose of global correlation. It is shown that the variations of 87Sr/86Sr throughout the Phanerozoic are related to the sea level changes. High-frequence(2.0 Ma) fluctuations in seawater 87Sr/86Sr consistent with third-order sequence. These changes are controlled by Sr sources of the seawater. There are two main Sr sources, one is“the continental Sr”with a high 87Sr/86Sr, which is input to seawater by flux, the other one is“the oceanic Sr”with a low 87Sr/86Sr, which is got into seawater directly by hydrothermal circulation through seafloor. Conodont is the idea sample for the studies because of its precise stratigraphic age and high Sr concentrations as well as relatively resistant to digenetic alternation. The 87Sr/86Sr curve of seawater constructed by using conodont is the best standard for global correlation. China possesses some unique geological records, such as the continuous sedimentation at the Permian/Triassic boundary, which is very helpful to supplement the gap in the87Sr/86Sr curve constructed for seawater from Permian to Jurassic by R. B. Koepnicket al(1998) on the basis of Burkeet al(1982).
Key words： Strontium isotope; Sea level change; Global correlation; Conodont.
[1] Capo R C, Depaolo D J. Seawater strontium isotopic variation from 2.5 million years ago to present[J]. Science, 1990,249:51～55.
[2] Hodell D A, Mueller P A, Mckenzie J A. Strontium isotope stratigraphy and geochemistry of the late Neogene ocean[J].Earth Planet Sci Lett, 1989,92:165～178.
[3] Burke W H, Denison R E, Hethermgton E A,et al. Variation of seawater87Sr/86Sr throughout Phanerozic time [J].Geology, 1982,10:516～519.
[4] Asmerom Y. Strontium isotopic variation of Neoproterozoic seawater: implication for crystal evolution[J]. Geochimica et Cosmochimica Acta, 1991,55:2 883～2 894.
[5] Montanez I P. Integrated Sr isotope variations and sea-level history of Middle to Upper Cambrian platform carbonates:Implication for the evolution of Cambrian seawater 87Sr/86Sr[J]. Geology,1996,24(10):917～920.
[6] Veizet J, Compton W.87Sr/86Sr composition of seawater during the phanerozoic [J]. Geochimica et Cosmochimica Acta,1974,38:1 461～1 484.
[7] Hess J, Bender M L, Schissing J G. Evolution of the ratio of 87Sr/86Sr in seawater from Cretaceous to present[J]. Science,1986,231:979～984.
[8] Gavish E, Friedman G. Progressive diagenesis in Quaternary to later Tertiary carbonate sediments: sequence and time scale[J]. J Sediment Petrol, 1969,39:980～1 006.
[9] Morrow D W, Mayers L R. Simulation of linestone dingeneses: a model based on strontium depletion [J].Canadian J Earth Sci, 1978,15:376～296.
[10] Spoomer E T C. The strontium isotopic composition of sea water, and seawater-oceanic crust interaction [J]. Earth Planet Sci Lett, 31:167～174.
[11] Mc Arthur. Recent trends in strontium isotope stratigraphy[J]. Terra Mova, 1994,6:331～359.
[12] Denison R E, Koepnick R B, Burke W H. Construction of the Cambrian and Ordovician seawater 87Sr/86Sr[J].Chermcal Geology,1998,152:325～340.
[13] Heather M S, Daniel P S. Effects of quatrnary sea level cycles on Sr in seawater [J]. Geochimica et Cosmochimica Acta, 1998,62(7):1 107～1 118.
[14] Denison R E, Koepnick B B, Fletcher A,et al.Criteria for the retention of original seawater in ancient shelf limestone[J]. Chemical Geology, 1994,112:131～143.
[15] Cummins D J, Elderfield H. The Strontium isotopic composition of Brigantian(late Dinantian) seawater[J]. Chemical Geology,1994,118:255～270.
[16] Diener A, Eloneth S, Veizer J.et al. Strontium isotope stratigraphy of the Middle Devonian: Brachiopods and conodonts[J].Geochimica et Cosmochimica Acta,1996,60:639～652.
[17] Kovach J. The Sr content of conodonts and possible use of the Sr concentrations and Srisotope composition of conodonts for correlation purpose[J]. Geological Society of America Abstracts with Programs, 1981,13:285～286.
[18] Stephen C, Ruppel Eric W J, James E B,et al.High-resolution 87Sr/86Sr chemistratigraph of the silurian: Implication for event correlation and Strontium flux[J]. Geology,1996,24(9):831～834.
[19] Epstein A G, Epstein J B, Harris L D. Conodont color alternation: An index to organic metamorphism [A]. In: US Geological Survey Professional Paper [C]. Washington:United State Government Printing office,1977.
[20] Ruppel S C, James E W, Barrick J E. Improvement in the Record of Secular Change in Sea-Water 87Sr/86Sr: A Stronger Bases for Dating of Paleozoic Digaenetic and Depositional Events[C]. AAPG Annual Convention Program, Honston,84A.
[21] Koepnick R B, Denison R E, Burke W H,et al.Construction of the Triassic and Jurassic portion of the Phanerozoic curve of seawater 87Sr/86Sr[J]. Chemical Geology, 1990,80:327～349.
[22] Schopf T J M. Permo-Triassic extinctions: relation to seafloor spreading[J]. Joumal Geology, 1974,82:126～143.
[23] Enos P, Wei Jiayong, Yan Yangji. Facies distribution province South China[J]. Sedimentary, 1997,44(3):563～584.
[24] Lehrmann, D J, Wei Jiayong, Enos D. Controls on facies architecture of large Triassic carbonate platform: the Grant Bank of Guizhou, Nanpanjiang Basin, South China[J]. J of Sedimentary Research, 1998,68(2):311～326.
[25] Yang Zunyi, Wu Shunbao, Yin Hongfu,et al. Geologic Accident in Transitional Permier-Triassic in Southern China[M]. Beijing: Geological Press,1991.
[26] Yin Hongfu, Tong Jinnan, Ding Meihua,et al. Sea level changes of later permier-Middle Triassic in Yangts area[J].Earth Science J of China Uni of Geology,1994,19(5):627～632.
/
| 〈 |
|
〉 |
甘公网安备62010202000687
