The Short-term Cycles of 87Sr/86Sr and CaC03 in Farly Miocene and the Implications for Pal eoceanography of the East Pacific

LIU Ji-hua; CHEN Ying-rong; LIANG Hong-feng; WANG Ying-xi

The piston core PC5794,698cm long,was recovered from the East Pacific Ocean. It is composed of Quaternary and early Miocene in stratigraphy. 55 nannofossils ooze samples of early Miocene(698-140cm,24.06-22.06Ma)were collected in the interval of 5cm,and the ⁸⁷Sr/⁸⁶Sr Isotope-MS,ICP and chemical method respectively. The fluctuations of ⁸⁷Sr/⁸⁶Sr and CaC0₃ through time display two and an half short-term cycles which are opposite in direction. The cycles are significant to paleoceanography. (1) The positive and negative cycles of ⁸⁷Sr/⁸⁶Sr reflect the increased trends of chemical weathering of old crust and volcanic activities in ocean respectively, while the positive and negative CaC0₃ cycles are constant with warming and cooling trends of paleoclimate. In general,the temperatures of air were lower in the eras of strong volcanic activity. (2) Compared to middle and late Miocene,the influences of the Antarctic Bottom Water to sedimentation and water of east Pacific were less important in early Miocene. But the Antarctic Bottom Water formed CaC0₃ dissolution and high contents of benthic foraminifera.

The Short-term Cycles of ⁸⁷Sr/⁸⁶Sr and CaC0₃ in Farly Miocene and the Implications for Pal eoceanography of the East Pacific

1. Institute of Marine Geology, MLNR, Qingdao, Shandong 266071;

2. Institute of Oceanology, Academia Sinica, Qingdao Shandong 266071;

3. Modern Analysis Center,Nanjing Univ,Nanjing 210093

Received Date: 1999-06-21

Publish Date: 1999-12-10

Key words:

the east Pacific Ocean Early Miocene cycles of ⁸⁷Sr/⁸⁶Sr and CaC0₃ paleoceanography /
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Abstract: The piston core PC5794,698cm long,was recovered from the East Pacific Ocean. It is composed of Quaternary and early Miocene in stratigraphy. 55 nannofossils ooze samples of early Miocene(698-140cm,24.06-22.06Ma)were collected in the interval of 5cm,and the ⁸⁷Sr/⁸⁶Sr Isotope-MS,ICP and chemical method respectively. The fluctuations of ⁸⁷Sr/⁸⁶Sr and CaC0₃ through time display two and an half short-term cycles which are opposite in direction. The cycles are significant to paleoceanography. (1) The positive and negative cycles of ⁸⁷Sr/⁸⁶Sr reflect the increased trends of chemical weathering of old crust and volcanic activities in ocean respectively, while the positive and negative CaC0₃ cycles are constant with warming and cooling trends of paleoclimate. In general,the temperatures of air were lower in the eras of strong volcanic activity. (2) Compared to middle and late Miocene,the influences of the Antarctic Bottom Water to sedimentation and water of east Pacific were less important in early Miocene. But the Antarctic Bottom Water formed CaC0₃ dissolution and high contents of benthic foraminifera.

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The Short-term Cycles of ⁸⁷Sr/⁸⁶Sr and CaC0₃ in Farly Miocene and the Implications for Pal eoceanography of the East Pacific

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The Short-term Cycles of ⁸⁷Sr/⁸⁶Sr and CaC0₃ in Farly Miocene and the Implications for Pal eoceanography of the East Pacific

1. Institute of Marine Geology, MLNR, Qingdao, Shandong 266071;

2. Institute of Oceanology, Academia Sinica, Qingdao Shandong 266071;

3. Modern Analysis Center,Nanjing Univ,Nanjing 210093

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The Short-term Cycles of 87Sr/86Sr and CaC03 in Farly Miocene and the Implications for Pal eoceanography of the East Pacific

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