西琛1井碳酸盐岩的矿物成分、地化特征及地质意义
Mineral content and geochemistry characteristics of carbonate rock in well No. Xichen-1 and geological significance
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摘要: 西沙群岛晚新生代碳酸盐岩是南海形成演化的产物,它的矿物组成、化学成分和Sr同位素组成可以较好地反映其形成时的古海洋环境.西沙群岛西琛1井是南海最深的全取心钻井,揭示3层白云岩和4层石灰岩.其中.白云岩层具有MgO含量高、Sr总量低的特点,同时出现岩盐、赤铁矿和菱锰矿等指相矿物,反映了古海水盐度较高的氧化环境,对应着三个冰期事件;石灰岩层具有MgO含量低、Sr总量高的特点,同时出现菱铁矿和黄铁矿等指相矿物,反映了古海水盐度较低的还原环境,对应着四个间冰期事件.整体上看,西沙群岛晚新生代碳酸盐岩中Sr的总量和87Sr/86Sr自下而上表现为递增趋势,受控于欧亚和印度板块碰撞引起的青藏高原隆升大的构造背景.但又具有明显的分层性,其中,中-上中新统白云岩层Sr含量偏低,而87Sr/86Sr增加趋势明显,与最大一次冰期事件引起的海退和强烈的白云岩化作用有关;上上新统-全新统石灰岩层Sr总量骤增,87Sr/86Sr明显减小,且变化幅度大,与中新世的白云岩化作用和第四纪幔源岩浆强烈喷发有关.
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关键词:
- 古海洋环境 /
- 碳酸盐岩矿物和地球化学成分 /
- 西沙群岛西琛1井 /
- 晚新生代
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[1] Banner JL and Hanson GN.1990. Calculation of simultaneous isotopic and trace element variations during water-rock interaction with applications to carbonate diagenesis.Geoclfim.Cesmochim.Acta,54:3123-3137
[2] Clemens SC,Famell JW and Gromet LP.1993. Synchronous charges in seawater strontium isotope composition and global climate.Nature,363:607-610
[3] Dasch EJ.1969. Strontium isotopes in weathering profiles,deep-sea sediments,and sedimentary rocks.Geochim.Cosmochim.Acta,33:1521-1552
[4] Davies TA,Hay WW,Southam JR et al.1977. Estimates of Cenozoic oceanic sedimentation rates.Science,197:53-55
[5] Elderfield H.1986. Strontium isotope stratigraphy.Paleogeography,Palaeoclimatology,Palaeecolngy,57:71 -90
[6] Emrich K and Fnhalt DH.1970. Carbon isotope fluctuation during the precipitation of calcium carbonate.Earth Planet Sci.Lett.,8:363 -371
[7] Fan QC,Sun Q,Li N et al.2004. Periods of vocanic activity and magma evolution of Holocene in North Hainsn Island.Acta Petrologica Sinica,20(3):533-544 (in Chinese with English abstract)
[8] Gerta K,Zsolt B,Thierry A and Doris S.2004. Cenomanian-Turonian and δ13C,and δ18 O,sea level and salinity variations at Pueblo,Colorado.Palcogeography,Palacoclimetohigy,Palcoecology,211:19-43
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