2009-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/704734摘要：本計畫是台灣與菲律賓的地體動力學研究計畫之子計畫，是三年整合型計畫的第三年，旨在通過對菲律賓Taal火山進行系統地地球化學研究，重建全新世以來 Taal 火山的噴發歷史，瞭解研究地區的古氣候和古環境變化。在第一年計畫中，對Taal湖及其周邊的水體和沉積剖面進行了採樣和分析工作，並采得3 根 0.4-1.2米長的重力岩芯，從大量的水樣分析中擇選了幾個帶有火山熱液特徵的元素和同位素。在第二年計畫中，對重力岩芯樣品進行14C法定年，得到非常精彩的核爆14C曲線，以及1千年來的沉積序列。對岩芯樣品進行了含水率、碳酸鹽、總有機碳、氮含量和碳氮同位素的測定，發現可能的火山活動影響湖泊沉積迴圈的現象。另外，在97年10-11月期間，在Taal湖西岸鑽取了84米深的岩芯，沉積物總長為65米，基本上穿透了泥質湖相沉積層。在98年度的計畫中，我們將對這65米長的岩芯進行岩性和地球化學分析。主要研究內容有：1. 14C定年；2. TOC, TON和TIC的量測；3. 有機相13C和15N的量測；4. 碳酸鹽13C和18O的量測；5. 沉積物薄片分析；6. 火山噴出物的SEM和TEM分析；7. 沉積物稀酸溶出相的化學元素含量分析；8. 計算Taal 湖化學元素輸入通量。 通過上述分析，本研究將對火山噴發的機制、古火山特徵指標、火山噴發與氣候變化的互動、以及湖體環境變化提供重要的科學理論和應用基礎。<br> Abstract: The present proposal is one sub-proposal of a 3-year integrated project so called: “Geodynamics of Taiwan and the Philippines”. This sub-proposal is the third year project for the on-going program. The sub-project aims to reconstruct the history of Taal volcanic eruption, paleoclimate and paleoenvironmental changes during the Holocene by studying geochemical properties of the volcanic system. During the first year of the project (2006-2007), we had investigated geochemical properties of Taal Lake system, including the main lake, crater lakes, Taal tributary steams, springs and rains. We collected more than 50 water samples for analyses of T, pH, dissolved O2, salinity, alkalinity, major/minor cations and anions, trace elements, heavy metals and isotopic compositions (such as 18O, D, 87Sr, 13C of DIC and Corg). These analyses allow us to filter out the important geochemical properties for detecting volcanic activity. We also retrieved three gravity cores from lake water depths of 100 m and 15 m, respectively. Four outcrops of paleo-eruption were sampled. During the second year of the project (2007-2008), two gravity cores (TLS1 and TLS2) have been analyzed and dated by AMS 14C. We obtained a beautiful bomb-introduced 14C curve from TLS2 and established the chronology of the core. We have measured water and TIC contents, TOC, TON, 13C and 15N of organic matter in the lake sediments. We found those apparent decadal cycles of water, TIC and TOC contents exist in the cores, being lower water, TIC and TOC contents corresponding to higher volcanic glass contents. These layers of lower water, TIC and TOC contents may reflect the periods of high volcanic activity. During Oct.-Nov. 2007, we drilled an 85-m deep core and recovered a 64-m sediment core from the western shore of Taal Lake. In this year, we plan to work on this long core. The analyses include: (1) radiocarbon dating; (2) measurements of TIC, TOC and TON; (3) measuring 13C and 15N of organic matter in the core sediments; (4) measurements of 13C and 18O in sedimentary carbonates; (5) conducting study of thin-sections of sediment slides for mineralogy and chemical compositions; (6) analysis of SEM and TEM on the sediment slides; (7) elemental analyses of acid leaching component; and (8) modeling the geochemical budgets of Taal Lake. Throughout the above analyses, we anticipate to understand the frequency, cyclicity, and controlling factor of Taal volcano eruption. This study will fill up the gap of paleoclimate and paleo-environmental history of the region.菲律賓Taal火山湖14C定年地球化學分析火山噴發機制全新世古氣候Taal LakeRadiocarbon datingGeochemistryVolcanic eruptionPaleoclimateHolocene