https://ir.lib.ncu.edu.tw/handle/987654321/66106 Search the Channel s https://ir.lib.ncu.edu.tw/simple-search https://ir.lib.ncu.edu.tw/handle/987654321/99337 title: 所羅門群島島弧岩漿作用的地球化學與年代學制約： 對隱沒帶極性反轉與地函域變化的啟示;Geochronological and Geochemical Constraints on Magmatism from the Solomon Island Arc: Implications for Subduction Polarity Reversals and Mantle Domain Shifts abstract: 摘要 俯冲极性反转(Subduction Polarity Reversals, SPRs)在岛弧岩浆记录中留下了独特的 地球化学印记,成为记录岩浆源演化及控制岩浆成因构造过程的可靠档案。自晚白垩世以 来,太平洋板块与印澳板块之间的相互作用导致了一系列长短不一的俯冲事件、微板块的 复杂参与以及西南太平洋地区伸展盆地的反复形成。安托亚瓦高原(Ontong Java Plateau, OJP)与所罗门群岛弧(Solomon Islands Arc, SIA)的碰撞及其与微陆块的相 互作用进一步加剧了该地区的构造复杂性。尽管已有研究记录了极性反转与碰撞事件,但 SIA在西南太平洋的确切起始时间与成因仍不明确。本研究通过对SIA岩浆样品的锆石U-Pb 定年、Hf同位素数据、全岩地球化学以及Sr-Nd-Hf-Pb同位素组成的综合分析,识别出三 个不同阶段的岛弧岩浆作用。 阶段1(约46 Ma) 包括来自圣伊莎贝尔岛(Santa Isabel)和乔伊索尔岛(Choiseul) 的低钾拉斑玄武质(tholeiitic, TH)岩石。这些岩石表现出N-MORB型稀土元素(REE) 分布特征,其全岩同位素比值表明其来源于原始地幔。阶段1样品在Hf–Nd同位素空间中显 示出太平洋地幔域的特征,被解释为在东北向俯冲的印澳板块之上,太平洋地幔楔部分熔 融所形成的岛弧岩浆。结合区域地质证据,该阶段被认为标志着SIA的第一次俯冲极性反 转(SPR),可能早在约65 Ma即已开始,与太平洋与澳大利亚板块运动方向变化有关。 阶段2(约35 Ma) 表现为来自吉佐岛(Ghizo)和新乔治亚群岛(New Georgia Group, NGG)的低钾钙碱性(calc-alkaline, CA)花岗岩的侵位。这些花岗岩显示出相对未分异 的REE分布及典型的岛弧地球化学特征,在蛛网图上表现为高场强元素(HFSEs,如Nb、Ta 和Ti)的显著亏损。其同位素特征显示出与印度型地幔源的亲缘关系。全岩同位素组成及 锆石εHf(t)值(+16.9至+13.2)表明其来源于经由上地幔上涌而生成的原始岩浆,该过 程发生在东北向板片断离事件之后。随后,路易西亚德高原(Louisiade Plateau)到达 Pocklington海槽,引发了向西南方向的俯冲,即第二次俯冲极性反转事件。 阶段3(约19 Ma至0.7 Ma) 包括来自新乔治亚群岛(NGG)和乔伊索尔岛的中至高钾钙碱 性(CA)岩石。这些岩石具有典型的岛弧地球化学特征,即大离子亲石元素(LILEs)和 轻稀土元素(LREEs)富集,同时高场强元素(HFSEs)亏损。其εNd(t)值(+7.2至+5.8 )和εHf(t)值(+13.3至+10.4)较前期阶段更低,表明地幔源区的异质性增强。我们推 vii 断,第三次SPR发生于约19 Ma,在约25–20 Ma安托亚瓦高原(OJP)抵达北所罗门海沟( North Solomon Trench, NST)之后,触发了OJP与印度型地幔域之间的相互作用。综合来 看,这三个阶段记录了多次重复发生的SPR事件,并限定了OJP–SIA碰撞的时间,该碰撞引 发了最新一次俯冲极性反转。 ;Abstract Subduction polarity reversals (SPRs) leave distinctive geochemical imprints in arc magmatic records, serving as robust archives for tracing magma source evolution and the tectonic processes controlling magma genesis. Since the Late Cretaceous, interactions between the Pacific and Indo- Australian plates have resulted in alternating long- and short-lived subduction episodes, complex involvement of microplates and the repeated formation of extensional basins across the southwest Pacific. The collision of the Ontong Java Plateau (OJP) with the Solomon Island arc (SIA) and its interaction with micro continental fragments have further complicated the tectonics. Although the polarity reversal and collision events have been documented, the precise timing and origin of the SIA in the southwest Pacific remain ambiguous. This study reports zircon U-Pb ages, Hf isotopic data, and whole-rock geochemistry as well as Sr-Nd-Hf-Pb isotopic compositions of magmatic samples from the SIA, revealing three distinct stages of arc magmatism. Stage 1 (~ 46 Ma) comprises a set of low-K tholeiitic (TH) rocks from Santa Isabel and Choiseul. These rocks exhibit N-MORB-like rare earth element (REE) patterns and their whole-rock Sr-Nd- Hf-Pb isotopic ratios suggest derivation from a depleted mantle source. Stage 1 samples display an affinity to the Pacific mantle domain in a Hf-Nd and 206Pb/204Pb versus 208Pb/204Pb isotopic space, and are interpreted as arc magmas generated by partial melting within the Pacific mantle wedge above the northeast-directed subduction of the Indo-Australian plate at the Pocklington Trough. Together with regional evidence, this stage is interpreted as marking the first reversal from SW- directed to NE-directed subduction, which may have initiated as early as ~65 Ma, accompanied by the changes in the Pacific and Australian plate motions. Stage 2 (~ 35 Ma) is marked by the emplacement of low-K calc-alkaline (CA) granites from Ghizo, New Georgia Group (NGG). These granites display relatively unfractionated REE patterns and arc-like geochemical signatures, ix marked by depletion in high field strength elements (HFSEs) such as Nb, Ta, and Ti in spider diagram. Their isotopic signatures show affinity with an Indian-type mantle source. Whole-rock isotopic compositions, together with zircon εHf(t) values ranging from +16.9 to +13.2, suggest derivation from a juvenile crustal source, generated by asthenospheric upwelling following a NE- directed slab break-off event. This event was subsequently followed by the arrival of the Louisiade Plateau at the Pocklington Trough, which triggered a southwest-directed subduction, the second reversal in subduction polarity. Stage 3 (~19 Ma to 0.7 Ma) comprises a set of medium- to high-K CA rocks from the NGG and Choiseul. These rocks exhibit typical arc-like geochemical signatures characterized by enrichment in large ion lithophile elements (LILEs) and light REEs, along with depletion in high field strength elements (HFSEs). Their less positive εNd(t) (+ 7.2 to + 5.8) and εHf(t) (+ 13.3 to + 10.4) values relative to earlier stage of magmas suggest involvement of enriched component. We infer a third SPR occurred ~ 19 Ma, following the ~25-20 Ma arrival of the OJP at the NST, which initiated interactions between OJP and Indian-type mantle domains. Collectively, these stages document recurrent SPR events and constrain the timing of the OJP–SIA collision that triggered the latest SPR. <br> https://ir.lib.ncu.edu.tw/handle/987654321/99335 title: 碳酸鹽與矽酸鹽體系中的三氧同位素分餾：實驗约束與 案例研究;Triple Oxygen Isotope Fractionation in Carbonate and Silicate Systems: Experimental Constraints and Case Studies abstract: 本論文系統性地探討三氧同位素系統在實驗、地質與環境脈絡中的行為機制，並以三氧同位素作為整合性的地球化學示蹤工具，用以解析連結岩石圈、水圈與大氣圈之間的物質與能量交換過程。研究首先從受控實驗室系統 CO₂–CaCO₃–H₂O 展開，透過探討 CO₂–H₂O 交換、碳酸鹽沉澱與酸溶反應過程中的同位素分餾行為，建立並量化相關的三氧同位素分餾關係，以改進對碳酸鹽三氧同位素訊號的詮釋（第三章）。 在此實驗基礎上，研究進一步應用於地質記錄，聚焦於瑪利諾期（Marinoan）帽碳酸鹽，該地層保存了「雪球地球」事件後熱液改變的同位素與礦物學證據。綜合的礦物學與同位素資料顯示，這些碳酸鹽曾經歷高溫流體–岩石作用，反映出一場全球同步的熱液事件（第四章）。 此外，本研究建立了矽酸鹽三氧同位素的高精度量測流程（第五章），並進行快速脫水實驗以檢驗含水矽酸鹽礦物在加熱脫水過程中的三氧同位素效應，進而提供新的分餾機制約束與動力學見解（第六章）。該技術亦應用於臺灣北部的大屯火山群，透過整合安山岩岩心的三氧同位素、主要與微量元素以及 Sr–Nd 同位素資料，解析其次火山岩漿的演化歷程（第七章）。 鑒於近期研究指出大屯地區可能存在岩漿庫，本論文進一步拓展至噴氣孔 CO₂ 的時間序列監測。結果顯示，碳、氧同位素與伽瑪射線放射資料可在近乎即時的時間尺度上捕捉微震動、熱液循環與岩漿逸氣之間的動態耦合關係，揭示火山系統於近地表環境中的複雜互動機制（第八章）。 ;This thesis investigates the behavior of triple oxygen isotope systems across experimental, geological, and environmental contexts, with triple oxygen isotopes serving as a unifying tracer of processes that link the lithosphere, hydrosphere, and atmosphere. It begins with controlled laboratory experiments on the CO2–CaCO3–H2O system, where fractionation during CO2–H2O exchange, carbonate precipitation, and acid digestion is explored and quantified to refine the interpretation of carbonate triple oxygen isotope signatures (Chapter 3). These experimental foundations are then applied to geological archives, focusing on Marinoan cap carbonates that preserve the imprint of post–Snowball Earth hydrother- mal alteration, where isotopic and mineralogical data together reveal high-temperature fluid–rock interaction during a globally synchronous event (Chapter 4). In parallel, a measurement protocol for silicate triple oxygen isotopes was established (Chapter 5), enabling further laboratory experiments that examine the triple oxygen isotope effects of rapid hydrous silicate mineral dehydration and provide new constraints on the na- ture of triple oxygen isotope fractionation (Chapter 6). In addition, the protocol was applied to the Tatun Volcano Group in northern Taiwan, where integrated triple oxygen isotope, major and trace element, and Sr-Nd isotope data from andesite cores illuminate the evolution of subvolcanic magmas (Chapter 7). Given reports of a present magma body, this motivated extending the study to time-series monitoring of fumarolic CO2 at Tatun, which demonstrates how coupled carbon, oxygen isotopes and gamma-ray radiation capture the dynamic interplay of micro-earthquakes, hydrothermal circulation, and magmatic degassing in near-real time (Chapter 8). <br> https://ir.lib.ncu.edu.tw/handle/987654321/99334 title: 利用電法與電磁地球物理技術進行水文地質成像：在兩個區域的可持續地下水管理中的應用;Hydrogeological Imaging Using Electrical and Electromagnetic Geophysics: Applications for Sustainable Groundwater Management in Two Regions abstract: 地下水文地質結構的空間非均質性會影響地下水的產生、流動及其相互作用。然而，僅依賴稀疏鑽孔資料的模型往往無法充分表徵這種變化。本研究利用電法與電磁法地球物理資料結合鑽孔資訊，對臺灣濁水溪沖積扇（CRAF）與衣索比亞塔納湖盆 Fogera 平原的水文地質特徵進行成像與表徵。研究共獲取 CRAF 區域 114 個 TEM（瞬變電磁）測點及 Fogera 平原 20 個 VES（垂向電測深）測點。CRAF 的 TEM 資料反演採用基於 VES 的先驗模型，而 Fogera 平原的 VES 資料反演則採用一維粒子群優化演算法。兩種方法均通過鑽孔記錄進行驗證。 在 CRAF 區域，結果顯示地表存在一薄的高電阻層，其下方為厚度約 40 m 的低電阻區。在該低電阻區之下，於 50–125 m 深度範圍內出現電阻率為 50–350 Ω·m 的高電阻層，大多數位置在更深處亦存在低電阻層。在 Fogera 平原，厚度變化為 8–40 m 的低電阻層位於中等電阻率單元（9–20 Ω·m）之上，其下約 40 m 深度處出現第二個低電阻層，而在約 70 m 以下則為高電阻區。插值後的二維剖面對鑽孔資料呈現出良好一致性。結果表明，CRAF 的結構序列為：無壓含水層—隔水層—含水層—隔水層；Fogera 平原則呈現隔水層—無壓含水層—隔水層—含水層的序列。電阻率深度切片圖及層次凝聚聚類（HAC）進一步突出這些結構的橫向變化與區域相似性。總體而言，本研究展示了 TEM 與 VES 在複雜水文地質環境成像及可持續地下水管理中的有效性。 ;The spatial heterogeneity of subsurface hydrogeological structures affects the occurrence, flow, and interaction of groundwater. However, models that rely solely on sparse borehole data often do not adequately represent this variability. This study uses electrical and electromagnetic geophysical data along with borehole information to image and characterize hydrogeological features of the Choushui River Alluvial Fan (CRAF), Taiwan, and the Fogera Plain, Tana Sab Basin, Ethiopia. A total of 114 TEM soundings in the CRAF and 20 VES measurements in the Fogera plain were acquired. A VES derived a priori model was used to invert TEM data in the CRAF, and a 1-D Particle Swarm Optimization algorithm was used to invert VES data in the Fogera Plain. Both methods were validated using borehole logs. In the CRAF area, results reveal a thin resistive surface layer, which is underlain by a low-resistivity zone approximately 40 m thick. Below this zone, high-resistivity layers ranging from 50 to 370 Ohm-m are found at depths between 50 m and 125 m, with deeper low-resistivity zones present in most locations. In the Fogera plain, a low-resistivity layer varying in thickness from 8–40 m is situated above a moderately resistive unit (9–20 Ohm-m), followed by a second low-resistivity layer at approximately 40 m depth, and a high-resistivity zone beneath ~70 m. The interpolated 2D sections show a strong correlation with borehole logs. This indicates a sequence of unconfined aquifer, aquitard, aquifer, and aquitard in the CRAF, as well as a sequence of aquitard, unconfined aquifer, aquitard, and aquifer in the Fogera Plain. Depth-slice resistivity maps and Hierarchical Agglomerative Clustering (HAC) further highlight lateral variations of these structures and zone similarities. Overall, the study demonstrates the effectiveness of TEM and VES for imaging complex hydrogeological settings for sustainable groundwater management. <br> https://ir.lib.ncu.edu.tw/handle/987654321/97911 title: 空間域濾波器與最佳化分割演算法結合 定義黑潮範圍及綜合趨勢分析;Combination of Spatial Domain Filters and Optimized Segmentation Algorithm to Delineate Kuroshio Extent and Comprehensive Analysis of Trends abstract: 大多數研究都是根據在標準網格位置或沿特定橫斷面測量的定量值來調查黑潮的。然而，本研究 將黑潮與其周邊水域區分開來，並利用衛星資料分析了 1993 年至 2020 年從單一網格到流域規模 的表面流趨勢。這種獨特的方法結合了分割和影像處理。當方差擬合優度大於 0.8 時，它比傳統 的閾值/直方圖技術更能有效地描繪出不均勻的黑潮範圍，對海洋學和氣候研究有所貢獻。 從劃定的黑潮來看，整體的流速呈現減弱的趨勢。為了分析其變化趨勢是均勻的還是隨區域變化 的，本研究根據水文特徵將已劃定的黑潮劃分為 5 個區域。使用三種統計方法、兩種頻率方法和 一種貝葉斯 (bayesian) 方法，以區域平均值和逐個像素為基礎分析其趨勢。值得注意的是呂宋島 和台灣沿岸的風力減弱。相反，吐噶喇海峽 (Tokara Strait) 至名古屋及名古屋-150°E 方向的風力 增強。有趣的是，黑潮南流-II 處存在著由減弱到加強的過渡區。在計算效率方面，檢測斷點和估 計趨勢段（DBEST）和小波轉換（WT）優於其他方法。集合經驗模態分解 (EEMD) 和季節性趨 勢 Loess (STL) 具有相似的效率水準。加性季節和趨勢斷點 (BFAST) 是為線性趨勢而設計的，而 EEMD 適用於一般趨勢。突變、季節性變化和趨勢的貝葉斯估計器 (BEAST) 結合了多種模型以 減少過度擬合，並從 GlobCurrent 和漂移數據中產生高度相關的趨勢。本研究探討結合空間濾波 演算法擷取海面流的適用性。因此，對光柵濾波器進行了 80-13,505 張每日影像的測試，以檢測 每週、季節和氣候尺度上的黑潮 (KC)。所選的柵格濾波器包括卷積、拉普拉斯、北梯度、銳化、 最小/最大、直方圖均衡化、標準差和自然斷點。此外，還採用了海面流、海面溫度（SST）、海 面高度（SSH）等常規資料集，以及總熱通量、表面密度（SSD）和鹽度（SSS）等非常規資料。 此外，由於很少有研究表明葉綠素-ff 可以作為夏季 SST 的替代物來提取 KC，因此納入了有爭議 的水色數據。有趣的是，只有結合演算法，過濾器的性能才是統一的，並且在季節和氣候尺度上 都能蓬勃發展. 與使用單獨的濾鏡和指定值譜來識別黑潮特徵的典型場景相反，本研究採用了不 同的方法。它研究了根據 SST、SSH、總熱通量、SSS、SSD、葉綠素-ff 和海面流計算出的黑潮中 心線之間的相關性。從台灣東北部經吐噶喇海峽到日本南部，黑潮中心線各段觀測到的熱通量、 葉綠素-ff 和表層鹽度資料有偏差，這很有啟發性。這種相關性凸顯了各種海洋數據的相互聯繫， 有助於更深入地了解黑潮系統。 ;Most studies investigated Kuroshio on quantitative values measured at standard grid locations or along a transect. However, this research delineates Kuroshio from its surrounding waters, and surface current trends are analyzed from 1993 to 2020, extending from a single location to a basin scale. This unique approach combines segmentation and image processing. When integrated with the goodness of variance fit greater than 0.8, it proves more efficacious than conventional threshold/ histogram techniques in delineating patchy Kuroshio extent contributing to oceanography and climate studies. The generalized trend from delineated Kuroshio exhibited a systemwide weakening. To analyze whether the trend is uniform or varies with Latitude, delineated Kuroshio is divided into five sections based on the hydrological characteristics. The trend was analyzed using three statistical, two frequency, and one Bayesian approach on a regional mean and a pixel-by-pixel basis. Weakening in Luzon and along Taiwan is worth noting. In contrast, a strengthening in the Tokara Strait to Nagoya and Nagoya-150°E. Interestingly, the transition zone from weakening to strengthening in the Kuroshio South-II. Regarding computational efficiency, Detecting Breakpoints and Estimating Segments in Trend (DBEST) and Wavelet Transform (WT) outperformed the other methods. Ensemble Empirical Mode Decomposition (EEMD) and Seasonal Trend Loess (STL) have similar levels of efficiency. Breaks for Additive Season and Trend (BFAST) is designed for a linear trend, while EEMD is suitable for a general trend. The Bayesian Estimator of Abrupt, Seasonal Change and Trend (BEAST) combines multiple models to reduce overfitting and produces highly correlated trends from GlobCurrent and drifter data. This research also investigates the applicability of combining spatial filter＇s algorithm to extract surface ocean current. Accordingly, the raster filters were tested on 80–13,505 daily images to detect Kuroshio Current (KC) on weekly, seasonal, and climatological scales. The selected raster filters are convolution, Laplacian, north gradient, sharpening, min/max, histogram equalization, standard deviation, and natural break. In addition, conventional data sets of sea surface currents, sea surface temperature (SST), sea surface height (SSH), and non-conventional data such as total heat flux, surface density (SSD), and salinity (SSS) were employed. Moreover, controversial data on ocean color are included because very few studies revealed that chlorophyll-α is a proxy for SST in the summer to extract KC. Interestingly, the performance of filters is uniform and thriving for seasonal and on a climatological scale only by combining the algorithms. Contrary to the typical scenario of identifying Kuroshio signatures using an individual filter and by designating a value spectrum, this research takes a different approach. It investigates the correlation between Kuroshio＇s centerlines computed from SST, SSH, total heat flux, SSS, SSD, chlorophyll-α, and sea surface currents. The deviations observed in the various segments of Kuroshio＇s centerline extracted from heat flux, chlorophyll-α, and SSS flowing across Tokara Strait from northeast Taiwan to south Japan are enlightening. This correlation highlights the interconnectedness of various oceanographic data, providing a deeper understanding of the Kuroshio system. <br>