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《河北阜平雜巖長(zhǎng)英質(zhì)片麻巖中一些淺色體的地球化學(xué)性質(zhì)及其地質(zhì)意義.pdf》由會(huì)員上傳分享,免費(fèi)在線閱讀,更多相關(guān)內(nèi)容在行業(yè)資料-天天文庫(kù)。
1、第28卷第7期地質(zhì)通報(bào)Vo1.28.No.72009年7月GE0L0GICALBULL1TINOFCHINAju1.,2009河北阜平雜巖長(zhǎng)英質(zhì)片麻巖中一些淺色體的地球化學(xué)性質(zhì)及其地質(zhì)意義任留東,楊崇輝,杜利林RENLiu—dong,YANGChong—hui,DULi—lin中國(guó)地質(zhì)科學(xué)院地質(zhì)研究所.北京100037InstituteofGeology,ChineseAcademyofGeologicalSciences,Bering100037,China摘要:阜平雜巖中的淺色體主要分為2種類型,早期淺色體基本沿片麻理分布,較富鉀長(zhǎng)石(微斜長(zhǎng)石)、石英,貧斜長(zhǎng)石.形成于低
2、水深熔或壓溶條件下,水含量較低,局部脫水但尚未達(dá)到整體脫水的程度;晚期淺色體切割現(xiàn)有的片麻理,較富斜長(zhǎng)石、石英,貧鉀長(zhǎng)石,形成于有水熔融條件下,平陽(yáng)奧長(zhǎng)花崗巖的出現(xiàn)即與晚期淺色體相對(duì)應(yīng)。南營(yíng)片麻巖、南營(yíng)淺色花崗片麻巖的地球化學(xué)性質(zhì)與其他片麻巖具有明顯的不一致性。淺色體的稀土元素配分型式較復(fù)雜,根據(jù)對(duì)元素相對(duì)富集或虧損的分析得知,大多數(shù)淺色體的形成受圍巖成分的控制,從早期淺色體向晚期淺色體發(fā)展,稀土元素含量向LREE相對(duì)虧損、HR_EE相對(duì)富集的方向轉(zhuǎn)化,某些微量元素有明顯的繼承性。與地球化學(xué)特征相比,礦物組合的確定對(duì)淺色體階段的歸屬判定更為重要。阜平雜巖變質(zhì)演化不是簡(jiǎn)單的進(jìn)變
3、質(zhì)脫水反應(yīng),其水分含量的變化十分復(fù)雜,對(duì)其深入研究有助于更好地了解該區(qū)地質(zhì)和構(gòu)造的演化過(guò)程關(guān)鍵詞:淺色體;稀土、微量元素;地球化學(xué);元素相對(duì)富集或虧損;阜平雜巖中圖分類號(hào):P588.345;P595文獻(xiàn)標(biāo)志碼:A文章編號(hào):1671-2552(2009)07-0857—10RenLD,YangCH,DuLL.GeochemicalfeaturesandgeologicalsignificanceoftheleucosomesinthequartzofeldspathicgneissesofFupingComplex,Hebei,China.GeologicalBulletino
4、fChina,2009,28(7):857—866Abstract:TheleucosomesinthequartzofeldspathicgneissesofFupingComplexcanbediscernedtOtWOtypes.Theearliertypeisrichinmicrochne,quartz,butpoorinplagioclaseandessentiallyalignedalongthefohadon.Thisleucosomeisformedunderlow—wateranatexisorpressuresolution,locallydehydrat
5、edbuthasnotbeenuptOthedegreeoftotaldehydrationasawhole.Cuttingthefolition,thelatetypeisrichinplagioclase,quartz,butpoorinK—feldspar,andisderivedfromwater—presentpartialmelting.ThePingyangtrondhjemitemaycorrespondwichthisstage.ButtheNanyinggneissandleucograniteareinconsistentwithothergneisse
6、softheregioningeochemistry.TheREEpatternsoftheleucosomesareverycomplicated.Accordingtotherelativeenrichmentordeple—tionofelements,wecandeducethatmostleucosomesarecontrolledbythehostbulkchemistry.FromtheearlierleucosometOthelaterone,theREEtendtOberelativelydepletedinL1LEEandenrichedinHREE,an
7、dsometraceelementsmayinheritthefeaturesofthehost.RelativetOthegeochemicalfeatures,itseemsthatthemineralassemblagesoftheleucosomesaremoreimportantforthestageascription.ThemetamorphismevolutionoftheFupingComplexisnotsimpleprogressivedehydrationandthewaterc