The relationship between the growth process of the ferromanganese crusts in the pacific seamount and Cenozoic ocean evolvement
The relationship between the growth process of the ferromanganese crusts in the pacific seamount and Cenozoic ocean evolvement
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DOI：
10.1007/s11430-009-0106-z
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发表时间：
2009-08
期刊：
影响因子：
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通讯作者：
Xuan Ding;Lian-feng Gao;Nian-qiao Fang;W. Qu;Jian Liu;Jiangshan Li
中科院分区：
文献类型：
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作者：
Xuan Ding;Lian-feng Gao;Nian-qiao Fang;W. Qu;Jian Liu;Jiangshan Li
根据Os同位素地层学和Co浓度经验生长速率模型，确定了太平洋海山铁锰结壳MHD 79和MP 3D 10的生长年龄。通过对ODP 144航次和中太平洋海山结壳CD 29 -2、N5 E-06、N1-15等已有成果的对比研究，发现它们具有统一的5个生长期和生长间断期，并与新生代海洋演化过程密切相关。古新世碳同位素极大期（皮姆），全球海洋生产力的上升促进了海山地壳的生长，铁锰结壳第一次生长间断（I）结束。古新世-始新世热盛期（PETM），虽然海水垂向交换减弱，但强烈的陆源化学风化作用导致陆源营养物质大量输入，生物生产力上升，不存在地壳间断。52-50 Ma为始新世早期最佳气候期（EECO），两极温暖，纬向温度梯度小，风驱动的海洋环流和上升流活动减弱，陆地风化作用也减弱，开阔洋生物生产力下降，铁锰结壳再次出现生长间断（II）。中始新世早期-晚始新世-渐新世为长期的逐渐冷却过程，海洋环流和上升流的加强导致生物生产力的提高，水成元素Fe、Mn、Co和生物元素Cu、Zn的含量增加，是研究区铁锰结壳生长的最有利阶段（生长期III和IV）。第III期裂孔对应始新世-渐新世界线，推测与始新世-渐新世过渡期全球气候转型、天体撞击事件有关。早中新世至中中新世，研究区铁锰结壳出现了一次大规模的生长间断（间断期IV），这可能与早中新世气候的短暂变暖和南极底层水的短暂撤退有关。之后，南极冰盖扩张，底层水环流加强，海洋肥力提高，一度中断的地壳在中新世晚期（生长期V）继续生长。
Base on the Os isotope stratigraphy together with the empirical growth rate models using Co concentrations, the growth ages of the ferromanganese crusts MHD79 and MP3D10 distributed in the seamount of Pacific are confirmed. Through the contrast and research on the previous achievements including ODP Leg 144 and the crusts CD29-2, N5E-06 and N1–15 of the seamount of the Central Pacific, the uniform five growth and growth hiatus periods of them are found, and closely related to the Cenozoic ocean evolvement process. In the Paleocene Carbon Isotope Maximum (PCIM), the rise of the global ocean productivity promoted the growth of the seamount crust; the first growth hiatus (I) of the ferromanganese crust finished. In the Paleocene-Eocene Thermal Maximum (PETM), though the vertical exchange of seawater was weakened, the strong terrestrial chemical weathering led to the input of a great amount of the terrigenous nutrients, which made the bioproductivity rise, so there were no crust hiatuses. During 52–50 Ma, the Early Eocene Optimum Climate (EECO), the two poles were warm, the latitudinal temperature gradient was small, the wind-driven sea circulation and upwelling activity were weak, the terrestrial weathering was also weakened, the open ocean bioproductivity decreased, and the ferromanganese crust had growth hiatus again (II). From early Middle Eocene-Late Eocene, Oligocene, it was a long-term gradually cooling process, the strengthening of the sea circulation and upwelling led to a rise of bioproductivity, and increase of the content of the hydrogenous element Fe, Mn and Co and the biogenous element Cu, Zn, so that was the most favorable stage for the growth of ferromanganese crust (growth periods III and IV) in the studied area. The hiatus III corresponded with the Eocene- Oligocene boundary, is inferred to relate with the global climate transformation, celestial body impact event in the Eocene-Oligocene transition. From the early to the middle Miocene, a large-scale growth hiatus (hiatus period IV) of the ferromanganese crust in the studied area is inferred to relate with temporary warm up climate and ephemeral withdrawal of Antarctic bottom water in the early Miocene. After that, the Antarctic ice sheets extended, the bottom water circumfluence strengthened, the ocean fertility increased, and the once interrupted crust continued to grow in the late Miocene (growth period V).