近2.1 Ma以来帕里西维拉海盆黏土矿物输入变化及其对中更新世气候转型的响应

Variation of clay mineral input in the Parece Vela Basin since the last 2.1 Ma and the response to the mid-Pleistocene climate transition

  • 摘要: 对帕里西维拉海盆PV090102孔2.1 Ma以来沉积物中黏土矿物的含量、特征参数和形貌特征进行了分析,结果表明,黏土矿物以伊利石(48%)和蒙皂石(34%)为主,绿泥石(13%)和高岭石(6%)含量较低。伊利石结晶度平均为0.29°△2θ,表明其形成于气候寒冷且水解作用弱的陆地源区;伊利石化学指数平均为0.32,表明该孔伊利石为富Fe-Mg伊利石,且经历了较强的物理风化。黏土矿物的组合特征和形貌特征表明,蒙皂石主要来源于周围火山岛弧,伊利石、绿泥石和高岭石主要来源于亚洲大陆风尘。在中更新世气候转型期,伊利石通量、绿泥石通量和高岭石通量均呈增加趋势,这与该孔总的风尘通量和风尘石英通量的变化趋势一致,且与亚洲大陆干旱化一致,表明其响应了中更新世气候转型期亚洲内陆的干旱变化,因而可以作为亚洲内陆干湿变化的示踪指标。此外,第四纪以来PV090102孔蒙皂石通量的变化与该孔火山物质通量的变化趋势具有很好的一致性,因而可以作为火山物质输入西菲律宾海的替代指标。

     

    Abstract: The composition and morphology of clay minerals collected from Core PV090102 in the Parece Vela Basin over the last 2.1 Ma were analyzed. Results show that the clays are mainly composed of illite (48% on average) and smectite (34%), and chlorite (13%) and kaolinite (6%). The illite crystallinity (0.29°Δ2θ) indicates that illite is mainly derived from cold and dry terrestrial regions; and the illite chemical index (0.32) implies that illite is rich in Fe-Mg and has experienced strong physical weathering. The clay mineral assemblage and morphological characteristics reflect that smectite is mainly derived from surrounding volcanic islands, while illite, chlorite, and kaolinite from Asian dust. The mass accumulation rates (MARs) of illite, chlorite, and kaolinite in Core PV090102 increased during mid-Pleistocene, which is consistent with the increase of MARs of eolian dust quartz in the Parece Vela Basin and Asia continent, suggesting that the MARs of illite, chlorite, and kaolinite in the Parece Vela Basin responded to the aridification in Asia during the mid-Pleistocene. Therefore, the MARs of illite, chlorite, and kaolinite in the Parece Vela Basin can be used to trace the paleoclimate change of Asian continent. In addition, variation of smectite MARs in Core PV090102 since the Quaternary is very consistent with the trend of volcanic material MARs in this core, and thus the variation can be used as a proxy of volcanic material input into the West Philippine Sea.

     

/

返回文章
返回