Using Sediments Examines the Chemical Weathering Proxy - the Simulate Systems of Experimental Petrology

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Project title

Code/計畫編號

NSC101-2116-M019-001

Translated Name/計畫中文名

利用沉積物探討化學風化指標(III) -實驗岩石學之模擬系統

Project Coordinator/計畫主持人

Huei-Fen Chen

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Institute of Earth Sciences

Website

https://www.grb.gov.tw/search/planDetail?id=2627595

Year

2012

Start date/計畫起

01-08-2012

Expected Completion/計畫迄

01-07-2013

Bugetid/研究經費

1262千元

ResearchField/研究領域

地球科學

"承繼前兩年在中國大陸和台灣地區湖泊岩心的研究計畫，本年度即將進入第三年的實驗岩石學驗證步驟，並將整合不同地區湖泊岩心之資料對比由實驗方法驗證所得的結果，進行統整。過去有感於諸多研究使用如Rb/Sr 比值與CIA 等做為化學風化指標，並且用於探討亞洲夏季季風的強弱，但這些指標使用於台灣地區的湖泊，卻發現有諸多矛盾的問題產生。首先是沉積物之母岩來源是否改變? 再則，風化過程各礦物元素遷徙的順序在侵蝕區和沉澱區有何不同?首先當沉積環境中的母岩來源改變時，將直接影響到礦物種類和元素比例，因此沉積物中的礦物分析相當重要。如果就封閉的湖盆環境而言，沉積物來源穩定，則可單純考量化學風化造成之元素遷徙順序。由於台灣和大陸北方的湖泊處於完全不同的酸鹼環境下，因此探討酸性和鹼性湖泊環境之元素遷徙和沉澱的順序為本研究須假設之重要前提。故本年度研究將嘗試使用實驗岩石學的方法，利用台灣不同地區的岩石做為母岩，包含沉積岩、火成岩和變質岩等三大岩類進行不同反應時間的酸溶與鹼溶試驗。用以模擬酸性和鹼性沉積環境下，各主要元素的溶解和遷移過程，以及計算黏土礦物種類和結晶度的變化。最後，尋求在不同原岩來源的環境下，最具代表性的化學風化指標。" "Following prior study projects of lake cores in China and Taiwan, this project will be proceeded with confirmable works of the experimental petrology in the third year. In addition, we will compare all data from the lake cores in different areas to organize the results of experimental petrology. Previous studies have used the Rb/Sr ratio and CIA as the chemical weathering proxies, and used theses proxies to interpret the intensity of Asian summer monsoon. When these proxies are used in Taiwan's lakes, however many contradictory problems will occur. First, does the origin of sedimentary parent rocks change? Second, is there any difference on the migration sequence of each element during weathering processes in the erosion and precipitation provinces? As the parent rocks of sedimentary origins changed, it will affect the mineral assemblages and elementary ratio in the sediments. Therefore, the mineral analysis of sediments is very important. In a closed environment of lake basin, we can simply consider the sequence of elemental migration during chemical weathering processes, when the origin of sediments is stable. Furthermore, we must probe the sequences of elementary migration and precipitation in acid and alkaline lake environments, because the lakes in Taiwan and North China are situated in different acid and alkaline environments. We will try to use the method of experimental petrology, and use the diverse parent rocks including sedimentary, igneous and metamorphic rocks to carry out the acid and alkaline dissolution. We can simulate the sequences of elementary migration and calculate the variation of clay mineral contents and crystallinity under the acid and alkaline environments. Finally, we want to find the typical weathering proxies from dissimilar parent rocks."

Keyword(s)

湖泊岩心
實驗岩石學
礦物
元素
化學風化

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Using Sediments Examines the Chemical Weathering Proxy - the Simulate Systems of Experimental Petrology

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