Deprecated: Assigning the return value of new by reference is deprecated in D:\nadm\history\ on line 75 地質名人館
  • 館藏編號:NTUG010-T700014
  • 題名:岩石地球化學及地球的演化
  • 作者:孫賢鉥
  • 藏品形式:稿本
  • 尺寸:297X210(mm)
  • 簡述:第一講:主要課題內容及其相關性
  • 內容:

    How about geotherm established by study of mantle xenoliths?
     Some sheared nodules 1450゚C, 200km: plumeeffect?
    b. Different processes involved
    different ages & tectonic history, e.g., deep root (~200km) of the Archean craton,  very refractory (high Fo, residual) as compared to younger terrains (denser & easier to delaminate); some alpine peridotites may represent recycled oceanic crust (rich in graphite, originally diamonds?, with δ^13C organic character -25); some highly metasomtized by subduction zone processes ± sediments (where?) ; some affected by intraplate LVZ meta somatism, mantle plume under plating, thermal erosion, delamination.
    c. Reactivation of the lithospheric mantle for magma generation
    Decompression, thermal erosion, heating by rifting, plume underplating: mixing of magmas derived from mantle plume and the low temperature melting & metasomatized potion of the plume derived melts?
    d. continental litheospheric mantle compared with oceanic lithenosphe less than 10% LIL elements of the bluk Earth stored in the continental lithospheric mantle?
    Elemental systematic observed in fertile spinel lherzalites → estinate & reconstruct the composition of the primitive mantle.
    Problem: secular systematic variations? E.g., different Ti/PGE in the Archean mantle and modern mantle? (apparently not).
    9. 地殼的形成和發展
    a. Why melt? Process involved & secular variation P.T.X, heat source.
    1. Orogenic magmatism: subduction, collision, underplating
    reconstruction indicators: ophiolites, boninites, K_2 O variation sedimentology……
    Kimverlite 常發生於超岩石圈之段震帶

    Tlood basalt 常為 plume head , 故其 isotope chemailer show: subcontinental lithospheric mantle + crust 參予