本文關(guān)鍵詞：10塊新疆哈密沙漠隕石的巖石礦物學(xué)特征和類型劃分及該地區(qū)隕石富集機制探討　出處：《中國科學(xué)院研究生院(廣州地球化學(xué)研究所)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 沙漠隕石 富集機制 隕石分類 巖石學(xué) 礦物成分

【摘要】：隕石是從行星際空間穿越大氣層燒蝕后到達(dá)地表的流星殘留體,代表了太陽系不同時間和空間的演化產(chǎn)物。我國有世界上公認(rèn)最早、最可靠的隕石記錄,但歷史上收集并保存下來的隕石數(shù)量不多,類型不全。除從南極獲得的大量隕石樣品外,國內(nèi)搜尋到的隕石樣品較少。沙漠是除南極地區(qū)之外的另一隕石富集區(qū)域,我國地域遼闊尤其是擁有面積廣闊的沙漠地區(qū),為隕石的保存提供了有利的地理條件。因此,尋找和回收沙漠隕石,對我國在該領(lǐng)域的研究將起到極大的促進(jìn)作用。隕石分類是根據(jù)隕石巖石-礦物學(xué)以及成分特征確定隕石類型,是隕石開展深入研究的基礎(chǔ)。本文通過對我國首次開展的專業(yè)隕石搜尋進(jìn)行地形、氣候和隕石聚集情況分析,探討隕石的富集機制,嘗試建立該地區(qū)隕石富集模型,以期為我國后續(xù)沙漠隕石的搜尋提供借鑒。哈密沙漠和附近戈壁地區(qū)由于氣候干旱、少或無植被、人跡稀少,為降落在該地區(qū)隕石的長期保存提供了有利的氣候條件。本次收集區(qū)域主要位于庫姆塔格沙壟兩側(cè),兩側(cè)風(fēng)向相對,于沙壟處交匯,這也是沙壟地形的形成原因,因此,風(fēng)的推進(jìn)使分散隕石隨其它沙石一起朝沙壟方向運移。在運移方向遇凸起地形也會阻擋運移物通過,而出現(xiàn)富集。此次搜尋在沙壟兩側(cè)圈定四個區(qū)域(分別記為I區(qū),II區(qū),III區(qū)和IV區(qū))。除II區(qū)和III區(qū)區(qū)內(nèi)存在零散陡峭的風(fēng)蝕殘丘外,區(qū)內(nèi)總體地勢平坦,區(qū)域周邊存在凸起地形阻擋的小殘丘。其中,I區(qū)位于庫姆塔格沙壟西側(cè)約20公里,南部靠近阿拉塔格山脈;II區(qū)位于庫姆塔格沙壟東側(cè)約50公里,南部靠近雅滿蘇鎮(zhèn);III區(qū)位于庫姆塔格沙壟東側(cè)約5公里,是最靠近沙壟的搜尋區(qū);IV區(qū)位于庫姆塔格沙壟東側(cè)約20公里,靠近南湖鄉(xiāng),是最靠北的搜尋區(qū)。I區(qū)搜集到42塊隕石,朝沙壟方向,隕石質(zhì)量呈現(xiàn)減小的趨勢;II區(qū)、III區(qū)和IV區(qū)收集到的隕石質(zhì)量均大于100g,最重約700g,且發(fā)現(xiàn)位置在殘丘坡腳附近,可能是降落在斜坡上的隕石在重力作用下滾落到山腳造成的。因此,哈密沙漠隕石的主要富集區(qū)域具以下幾個特點:1)順風(fēng)方向阻擋物之前更富集;2)沙壟附近地形平坦處富集;3)較陡殘丘坡腳處富集。此次新疆哈密沙漠隕石搜尋共收集到46塊隕石樣品,本文選取其中10塊代表性隕石,無水條件下磨制成光片和薄片,進(jìn)行巖石學(xué)、礦物學(xué)和礦物組成化學(xué)成分特征研究,并對其進(jìn)行類型劃分,確定它們的化學(xué)群、巖石類型、風(fēng)化程度、沖擊變質(zhì)程度。光片和薄片在光學(xué)顯微鏡下進(jìn)行巖相觀察,包括球粒和基質(zhì)的結(jié)構(gòu)特征、不透明礦物的種類、含量和分布、沖擊變質(zhì)特征和風(fēng)化程度。10塊隕石均具球粒結(jié)構(gòu),為典型的普通球粒隕石。1塊樣品Kumtag014球粒非常清晰,類型多樣,基質(zhì)未發(fā)生重結(jié)晶,巖石類型為3型。其余9塊隕石經(jīng)歷了明顯的熱變質(zhì)作用,基質(zhì)中等重結(jié)晶,球粒輪廓模糊,但仍然可以分辨,定為5型。3塊隕石(Hami003、Hami004和Kumtag014)僅金屬周邊發(fā)生輕微的褐鐵礦化,風(fēng)化類型為W1型;6塊隕石(AM007、AM008、AM011、AM015、AM020、Hami005)鐵鎳金屬和隕硫鐵部分被氧化成褐鐵礦,風(fēng)化類型為W2型;1塊隕石(AM027)鐵鎳金屬和隕硫鐵發(fā)生強烈氧化,定為W3型。1塊隕石(Kumtag014)橄欖石顆粒完整,無裂隙,無金屬熔滴,沖擊類型定為S1型;4塊隕石(AM015、AM020、AM027和Hami004)橄欖石有裂隙,無金屬熔滴,定為S2型;5塊隕石(AM007、AM008、AM011、Hami003和Hami005)金屬熔滴廣泛分布,定為S3型。硅酸鹽和不透明礦物化學(xué)成分由電子探針進(jìn)行測定。電子探針定量分析的實驗條件是加速電壓15k V、束流20n A,硅酸鹽采用天然礦物標(biāo)樣,金屬采用金屬或氧化物標(biāo)樣。分析數(shù)據(jù)采用ZAF(原子序數(shù)、吸收效應(yīng)及熒光效應(yīng))法校正。Kumtag014(Fa9.1-48.3,PMD=51.0;Fs2.8-30.3,PMD=54.2)屬于L群,組成礦物化學(xué)成分變化大。依據(jù)橄欖石Fa的相對標(biāo)準(zhǔn)偏差(PMD=51.0)將其進(jìn)一步劃分為3.4亞型,屬于相當(dāng)原始的球粒隕石樣品;AM007、AM008、AM011、AM015、AM020、AM027和Hami004,7塊隕石(Fa22.6~25.9,Fs17.6~21.4)屬于L群;Hami003、Hami005,2塊隕石(Fa18.2~20.8,Fs16.0~17.8)屬于H群。
[Abstract]:Meteorites are from interplanetary space through the atmosphere after the ablation to the surface of the meteor residue, which represents the product evolution of solar system in different time and space. China has the world recognized the earliest, most reliable meteorite record, but the history of the collection and the number of meteorites preserved much, incomplete type. In addition to a large number of meteorites from the Antarctic, home to search the meteorite samples less. The desert is another Antarctic meteorites except outside the region rich area, China is a vast country especially with the desert area of the vast area, provide favorable geographical conditions for the preservation of the meteorite. Therefore, search and recovery of desert meteorites, will play a great to promote research in the field of our country. According to the classification of meteorite meteorite types determine the meteorite rock mineralogy and composition characteristics, is the basis for further research. Based on the meteorite carried out in China for the first time To carry out professional search for meteorites terrain, climate analysis and aggregation of meteorites, meteorites enrichment mechanism, try to establish the reference area meteorites enrichment model, in order to search for China's future. The Hami desert and desert meteorites near the Gobi area because of the dry climate, with little or no vegetation, sparsely populated, provide favorable the climate conditions for the long-term preservation of land in the area. The meteorite collection areas are mainly located in kumutage sand ridge on both sides, both sides of the wind relative, at dune interchange, which is also the reasons for the formation of sand dune terrain, the wind dispersed with other meteorites advancing together in the sand dunes. In case of convex direction migration the terrain in migration direction will stop migration through, and enrichment. The search in the sand ridges on both sides delineated four regional (referred to as I area, II area, III area and IV area). In addition to the II district and III District in zero memory Bulk erosion monadnock steep, the overall area is flat, area surrounding the existence of hill barrier little monadnock. Among them, the I area is located about 20 kilometers west of kumutage sand ridge, south near arrata lattice mountains; II area is located about 50 kilometers east of kumutage sand ridge, south near the Yamansu town; III District is located about 5 km east of kumutage sand ridge, is the most close to the sand dunes of the search area; IV area is located about 20 kilometers east of kumutage sand ridge, near South Lake Township, is the northernmost search zone.I collected 42 meteorites, in the sand ridge direction, reduced trend meteorite quality; II area, III area and IV area to collect the quality of meteorites were more than 100g, the weight is about 700g, and found the location in the vicinity of the residual hill slope, may be landed on the slope under the action of gravity meteorite fallen to the mountain caused. Therefore, the main rich Hami desert meteorites set out the following areas Features: 1) before the direction of wind barrier more enrichment; 2) sand dunes near the flat terrain at a steep slope enrichment; 3) enrichment. The monadnock Xinjiang Hami desert meteorite search collected 46 meteorite samples, this paper selects 10 representative meteorites, anhydrous conditions polished and thin film to study on the characteristics of petrology, mineralogy and Mineral chemical composition, and classified into different kinds, determine their chemical groups, rock types, weathering degree, degree of shock metamorphism. Light sheet and sheet by petrographic observation under optical microscope, the structure features including chondrules and matrix, kinds of opaque minerals, content and distribution, shock metamorphic features and the weathering degree of.10 meteorites are variolitic texture, as ordinary chondrites.1 samples Kumtag014 chondrules typical is very clear, various types of matrix recrystallization did not occur, the rock type is the type 3. 浣，

本文編號：1436052