在第四紀的研究中，在環境及氣候變遷、人類的演進，年代學均扮演者不可或缺的串聯角色，而鈾系定年法為目前最為廣泛所使用的定年方法。利用（230Th/234U）定年可以提供45萬年的年代學記錄，而目前鈾系定年法常應用於碳酸鹽類的地質樣品，例如：珊瑚、鐘乳石，以及牙齒化石樣品。而在過去的研究中，對於牙齒化石是否適合作為定年的地質材料，目前仍有爭議，主要原因在於牙齒化石並非處於封閉系統下。因此鈾在牙齒化石中的遷移機制便顯得相當重要，經由模式的推演可以獲得校正後的年齡；目前仍然沒有一個模式可以完全說明鈾的遷移機制，可見得影響因素相當複雜。
　　本研究首先分析國際標準樣品，包含三個珊瑚標準樣品（RKM-4、RKM-5及JCp-1）以及三個鐘乳石標準樣品（76001、GBW04412及GBW04413），利用高解析度感應耦合電漿質譜儀（HR-ICP-MS）進行量測。在上述的標準樣品中，只有JCp-1有微量元素之定量數據，經由本研究的分析結果與過去的研究結果比較，審視儀器分析方法是否得宜，同時並建立其他標準樣品微量元素的資料庫。
　　在針對牙齒化石中的微量元素分佈，本研究利用雷射剝蝕系統進行牙齒化石的線性剖面掃瞄，再同樣利用高解析度感應耦合電漿質譜儀（HR-ICP-MS）進行量測，藉以瞭解牙齒化石中的元素分佈。根據Millard以及Hedges所提出的擴散吸附模式（Diffusion-Adsorption Model），鈾在不同的遷移機制下，可以推演出不同的鈾分佈情形，亦顯示是否具有代表年齡的意義，藉以評估牙齒化石的定年價值。
　　初步結果顯示，鈾富集於牙齒中象牙質的部分，釷在牙齒化石中的含量非常低，使得230Th對於定年結果的影響相對降低，就定年的角度來說，實為極大的優勢；而Fe、Mn、Al、Pb則富集於牙齒中黑色斑紋的區域以及裂隙的地方，顯示牙齒化石樣品可能受到些許的成岩作用影響。即使如此，從鈾的分佈曲線，在象牙質中的分佈是相當一致的，顯示鈾於牙齒化石中可能已達到飽和，具備可測得準確年齡的可能性。

　　In the Quaternary research, a precise chronological controlling method plays the most significant role in connecting the evolution processes of environment, climate and human being. The U-series dating is the most powerful method to apply in Quaternary, especially the radiogenic pairs of 234U and 230Th. The 234U-230Th method can be used to provide precise age up to 450 thousand years. At present, there are many geological samples dated with U-series including carbonates, corals, speleothems and fossil teeth. In order to obtain an accurate age, one has to assure all samples were in a closed system, otherwise, it is necessary to correct the artifacts by applying proper model calibration. Especially for the fossil teeth dating, it is still a series problem whether the obtained age is accurate or not. Hence, it is important to study how uranium migrated into the fossil teeth and how to create a proper model to calibrate these ages.
　　Aimed to check the instrumental parameters, we have analyzed several international carbonate standards, including three coral ( RKM-4、RKM-5 and JCp-1 ) and three speleothems ( 76001、GBW04412 and GBW04413 ) standards. We used standard addition method to quantify these standards using a high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). There is no trace element composition available in these standards, except for JCp-1. A comparison of JCp-1 results with previous measurements allows us to evaluate systematically of the ICP-MS technique. On the other hand, a new database of trace element compositions can be certified for these international standards.
　　For the fossil teeth, major, minor and trace elements were pre-scanned using laser ablation before HR-ICP-MS analyses. According to the Diffusion-Adsorption Model suggested by Millard and Hedges, the uranium distribution patterns in the fossil teeth provide information on preservation status and if is worthy of efforts for dating. The trace elements distribution also can be used to evaluate the artifacts after buried.
　　The preliminary results indicate that uranium was enriched in the dentine compared with enamel. There is low thorium in the teeth except where fracture located. This indicates the overestimation of ages due to uptake of 230Th is unlikely. Moreover, Fe, Mn, Al, and Pb shows similar distribution in the crack or certain spots of the teeth, probably relatd to diagenesis. In summary, the uranium distribution is concentrated in the dentine, and is apparently saturated and therefore an accurate age is likely can be obtained.

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