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1、2012年12月,第18卷,第4期,759—764頁高校地質(zhì)學(xué)報December2012,Vo1.18,No.4,P.759-764GeologicalJournalofChinaUniversities川西平原中更新世網(wǎng)紋紅土主量元素地球化學(xué)特征應(yīng)立朝1,梁斌,王全偉2,朱兵,郝雪峰,王鑫,劉亮,付小方1.西南科技大學(xué)環(huán)境與資源學(xué)院,綿陽621010;2.四川省地質(zhì)調(diào)查院,成都610081摘要:川西平原中更新世網(wǎng)紋紅土地球化學(xué)分析結(jié)果表明,網(wǎng)紋紅土的主量元素組成具有較好的一致性,以SiO,,F(xiàn)e,O和A12O3為主,三者含量之和平均值為90.9
2、2%;K2O,Na20,CaO和MgO等易溶組分含量低,除K:O含量略高于1%外,其余氧化物均不足1%。相對于上陸殼(UCC)平均組成,主量元素富集TiO:,TFeO,貧Na2O,MgO,P2O,K:O,MnO。樣品中的Fe:O,AI:O,RO。(Fe:O+A1O)與SiO含量呈明顯的負相關(guān)關(guān)系,表明該地區(qū)網(wǎng)紋紅土符合亞熱帶地區(qū)脫硅富鋁或脫硅富鋁鐵的成土過程,總體形成于濕熱環(huán)境。通過化學(xué)蝕變指數(shù)(CIA)、風(fēng)化淋溶系數(shù)(BA)和A—CN—K圖解等對比分析,該區(qū)中更新世網(wǎng)紋紅土的化學(xué)風(fēng)化強度與九江紅土、宣城紅土相近,認為該區(qū)網(wǎng)紋紅土在濕熱環(huán)境下遭受
3、了強烈的化學(xué)風(fēng)化作用,同時也表明中更新世川西平原與長江中下游地區(qū)具有相似的古氣候環(huán)境。關(guān)鍵詞:網(wǎng)紋紅土;主量元素;中更新世;川西平原中圖分類號:P539.2;P595文獻標識碼:A文章編號:1006—7493(2012)04~0759—06MajorElementsCharactersoftheMiddlePleistoceneVermicularRedClayfromtheWesternSichuanPlainYingLichao’,LiangBing’。,WangQuanwei,ZhuBing,HaoXuefeng,WangXin’,LiuL
4、iang’,F(xiàn)uXiaofang1.SchoolofEnvironmentandResourceofSouthwestUniversityofScienceandTechnology,Mianyang621010,China;2.SichuanGeologicalSurvey,Chengdu610081,ChinaAbstract:Thechemica1compositionofthemiddlePleistocenevermicularredclayfromtheWestemSichuanPlainshowsthattheoxidesofSiO
5、2,F(xiàn)e2O3andA12O3arethreedominantcomponents,whichhasanaverageof90.92%totally。ThecontentsofthesolubleelementssuchasNa20,CaOandMgOarelowerthanl%exceptK20.Comparingwiththeuppercontinentalcrust—normalized(UCC)value,theTiO2andTFe2O3areenrichedand,theNazO,MgO,P2O5,K2OandMnOaredeplete
6、d.TherearesignificantlynegativecorrelationsbetweenSiO2withtheotherthreeoxidesofFe2O3,A12O3and,R2O3(Fe2O3+A12O3),whichindicatethatthevermicularredearthunderwentwet—hotweatheringanddesilicification—allitizationprocess.Thecorrelationofchemicalindexofalteration(CIA),coeficientofw
7、eatheringandeluviations(BA)andA—CN—KternarydiagramshowthatthereisasimilarchemicalweatheringintensityoftheredclayintheJiujiangareaandintheXuanchengareaofeasternChina.WesuggestthatthevermicularredclayinwesternSichuanalsounderwentthestrongchemicalweatheringinahotandhumidenvironm
8、entwhenredclayformed,andthepaleoclimaticenvironmentinthewesternSichu