江西相山火山-侵入杂岩及其包体稀土元素地球化学
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摘要
本文综合性地报道了江西相山中生代中、酸性火山 -侵入杂岩的稀土元素地球化学研究 ,以探讨基底变质岩、火山岩、次火山岩及闪长质包体之间的成因联系和差异性。认为此套火山 -侵入杂岩具同源演化关系 ,推测它们均来源于前震旦系结晶基底 ,成因上属于陆壳重熔型。这与前人对此研究的主流观点是一致的 ,同时更具完整性和系统性。
The dark coloured enclaves were found in subvocanic dike for the first time in the Xiangshan district, Jiangxi Province, which provides a new information for studying Mesozoic vocanic intrusive complex in this region. This kind of enclaves exsit in small amounts, with chilled margin, back veins, and other obvious quenching characteristics. Petrologically they are mainly dioritoids. We collected 14 samples, including the basemental rocks,vocanic rocks,subvocanic rocks and dark enclaves, and made detailed REE analyses on them. Combining with the previous study, we tried to explain the genetic relationship and difference between them in a more integrated and systematic way. The data and diagrams demonstrate that: 1) as a whole, the magmas which formed various volcanic rocks with slight to intermediate fractionation degree of REE and strong europium negative anomalies, were differentiated and evolved in the same magmatic reservoir. The latter was originated from the continental crust; 2) products of the bicyclic volcanic activity, rhyodacite and porphyroclast lava, represent double emptying of magma reservoir; 3) REE data of dioritic enclaves don't show strong europium negative anomalies. Conseguently we concluded that the the magma of these enclaves was derived from a deeper level, and could be a mixture of lower crust and enriched mantle with a higher mixing proportion. Furthermore, Pb, Sr, Nd isotope data also provided similar information. εNd(t) of volcanics and subvocanics are -8.8 and -11.2, respectively, which are very close to the upper crust value in southeast China, while that for the dioritic enclaves is -6.5, which indicates involvement of a deeper source component. Mesozoic vocanic intrusive complex in Xianshan district was generated by the partial melting of sialic lithosphere and belongs to the S type in origin, which is consistent with the popular point of view. However, discovery of dioritic enclaves implies possible participation of lower crust or even upper mantle component.
The dark coloured enclaves were found in subvocanic dike for the first time in the Xiangshan district, Jiangxi Province, which provides a new information for studying Mesozoic vocanic intrusive complex in this region. This kind of enclaves exsit in small amounts, with chilled margin, back veins, and other obvious quenching characteristics. Petrologically they are mainly dioritoids. We collected 14 samples, including the basemental rocks,vocanic rocks,subvocanic rocks and dark enclaves, and made detailed REE analyses on them. Combining with the previous study, we tried to explain the genetic relationship and difference between them in a more integrated and systematic way. The data and diagrams demonstrate that: 1) as a whole, the magmas which formed various volcanic rocks with slight to intermediate fractionation degree of REE and strong europium negative anomalies, were differentiated and evolved in the same magmatic reservoir. The latter was originated from the continental crust; 2) products of the bicyclic volcanic activity, rhyodacite and porphyroclast lava, represent double emptying of magma reservoir; 3) REE data of dioritic enclaves don't show strong europium negative anomalies. Conseguently we concluded that the the magma of these enclaves was derived from a deeper level, and could be a mixture of lower crust and enriched mantle with a higher mixing proportion. Furthermore, Pb, Sr, Nd isotope data also provided similar information. εNd(t) of volcanics and subvocanics are -8.8 and -11.2, respectively, which are very close to the upper crust value in southeast China, while that for the dioritic enclaves is -6.5, which indicates involvement of a deeper source component. Mesozoic vocanic intrusive complex in Xianshan district was generated by the partial melting of sialic lithosphere and belongs to the S type in origin, which is consistent with the popular point of view. However, discovery of dioritic enclaves implies possible participation of lower crust or even upper mantle component.
引文
①范洪海 ,沈渭洲 ,王德滋 ,等 .江西相山基底变质岩及盖层火山岩的铅同位素研究 .(待版 )
[1] 夏林圻 ,夏祖春 ,张诚 ,RClocchiatti,JDardel,JLJoron .相山中生代含铀火山杂岩岩石地球化学 .北京 :地质出版社 ,1992 .[XiaLingi,XiaZuchun ,ZhangCheng ,ClocchiattiR ,DardelJ,JoronJL .PetrogeochemistryofMesozoicuranifer ousvolcaniccomplexfromXiangshan ,China .Beijing :GeologicalPublishingHouse ,1992 .]
[2 ] 王德滋 ,刘昌实 ,沈渭洲 ,陈繁荣 .江西东乡 -相山中生代S型火山岩带的发现及其地质意义 .科学通报 ,1991,(19) :1491 1493 .[WangDezi,LiuChangshi,ShenWeizhou ,ChenFangrong .FindingoftheMesozicS typevolcanicrockzoneinDongxiang -XiangshanofJiangxianditsgeologicalsignificance.ChineseScienceBulletin ,1991,36 (19) :1491 1493.]
[3] 沈渭洲 ,陈繁荣 ,刘昌实 ,王德滋 .江西两类火山侵入杂岩的同位素地球化学特征和物质来源 .岩石学报 ,1992 ,8(2 ) :177 184.[ShenWeizhou ,ChenFangrong ,LiuChangshi,WangDezi.Characteristicsofisotopicgeochemistyandmaterialsourcesoftwotypesofvolcanic intrusivecomplexesinJiangxi.ActaPerologicalSinica ,1992 ,8(2 ) :177 184.]
[4 ] 方锡珩 ,侯文尧 ,万国良 .相山破火山口火山杂岩体的岩石学研究 .岩矿测试 ,1982 ,1(1) :2 9.[FangXiheng ,HouWenyao ,WanGouliang .PetrographicstudiesofthevolcaniccomplexintheXiangshanCaldera .ActaPetrologicalMiner alogicaetAnalytica ,1982 ,1(1) :1 10 .]
[5 ] 徐克勤 ,朱金初、刘昌实 ,沈渭洲 ,徐士进 .华南花岗岩类的成因系列和物质来源 .南京大学学报 (地球科学版 ) ,1989,3 :1 18.[XuKeqin ,ZhuJinchu ,LiuChangshi,ShenWeizhou ,XuShijing .ThegeneticseriesandmaterialsourcesofgranitoidsinSouthChina .JournalofNanjingUniversity(EarthSciencesEdition) ,1989,3 :1 18.]
[6 ] HendersonP ,ed .Rareearthelementgeochemistry .Amsterdam :Elsevier ,1984.
[7] 陈小明 ,陆建军 ,刘昌实 ,等 .桐庐、相山火山 -侵入杂岩单颗粒锆石U Pb年龄 .岩石学报 ,1999,15 (2 ) :2 72 2 78.[ChenXiaoming ,LuJianjun ,LiuChangshi,ZhaoLianze,WangDezi,LiHuimin .Single grainzirconU Pbisotopicagesofthevolcanic intrusivecomplexesinTongluandXiangshanareas.ActaPetrologicalSinica ,1999,15 (2 ) :2 72 2 78.]
[8] CastroA .etc .H type (hybrid) granitoid :aproposedrevisionofthegranite typeclassificationandnomenclature .EarthSeienceReviews,1991,31:2 37 2 5 3 .
[9] 梁良 ,刘成东 ,李建红 .相山火山岩成岩构造环境的地球化学判据 .江西地质 ,1993 ,7(4 ) :2 81 2 91.[LiangLiang ,LiuChengdong ,LiJianghong .GeochemicalintergretationofpetrogeneticstructureenvironmentofthevolcanicrocksinXi angshan .JiangxiGeology ,1993,7(4 ) :2 81 2 91.]
[10 ] 陈迪云 ,周文斌 ,吴伯林 .相山碎斑熔岩铷 -锶、氧、铅同位素地球化学研究 .南京大学学报 (地球科学版 ) ,1994,6 :45 5 0 .[ChengDiyun ,ZhouWengbing ,WuBolin .StudyonRb ,Sr,O ,andPbisotopicgeochemistryoftheXiangshanclastoporphyriticlava .JournalofNanjingUniversity(EarthSciencesEdition) ,1994,6 :45 5 0 .]
[11] 廖群安 ,李昌年 ,王京名 .江绍断裂带晚侏罗世S型火山岩特征及其地质意义 .地球科学 ,1999,2 4(1) :6 3 6 8.[LiaoQun’an ,LiChangnian ,WangJingming .CharacteristicsofS typevolcanicrocksoflateJurassicperiodinJiangshaofracturezoneandtheirgeologicalsignificance.Earth ,1999,2 4(1) :6 3 6 8.]
[12 ] HildenP .,HallidayAN ,StephensWE .Neodymiumandstrontiumisotopecontentofmicrodioriteenclavespointstoman tleinputtogranitoidproduction .Nature,1989,330 (5 ) :5 4 5 6 .
[13] 刘昌实 ,沈渭洲 ,熊小林 ,王德滋 .江西岩背火山 -侵入杂岩的微量元素协变关系及其岩浆成分分带形成机制的探讨 .岩石学报 ,1994,10 (2 ) :15 1 16 0 .[LiuChangshi,ShenWeizhou ,XiongXiaoling ,WangDezi.CovarianceplotsoftraceelementsanddiscussiononacompositionalzonationofmagmachambersforYanbeivolcanic intrusivecomplexinJiangxiProvince .ActaPetrologicaSinica ,1994,10 (2 ) :15 1 16 0 .]
[14] 杨浩 .论痕量元素协变关系的应用 .地质论评 ,1990 ,36 (1) :6 9 80 .[YangHao .Applicationoftraceelementcovari anceplots.GeologicalReview ,1990 ,36 (1) :6 9 80 .]
[15 ] 董传万 ,彭亚明 .浙江青田花岗岩中岩石包体特征及成因 .岩石矿物学杂志 ,1994,2 2 (1) :2 3 30 .[DongChuanwan ,PengYaming .ThefeaturesandoriginoftheenclavesintheQingtiangranite ,ZhejiangProvince.ActaPetrologicaetMin eralogica ,1992 ,11(1) :2 1 30 .]
[16 ] 徐夕生 ,周新民 .花岗岩类中的岩石包体 .南京大学学报 (地球科学版 ) ,1988,1:2 33 2 39.[XuXisheng ,ZhouXin min .Rockinclusionsingranitoids.JournalofNanjingUniversity (EarthSciencesEdition) ,1988,1:2 33 2 39.
[17] 周金城 ,徐夕生 ,等 .寄主花岗岩对微花岗岩类包体的地球化学制约 .地球化学 ,1994,3 :2 5 4 2 6 1.[ZhouJincheng ,XuXisheng ,TaoXiancong .Geochemicalconstraintsonmicrogranitoidenclavesbyhostgranites .Geochemica ,1994,2 3(3) :2 5 4 2 6 1.]
[18] 王德滋 ,周金城 .我国花岗岩研究的回顾与展望 .岩石学报 ,1999,15 (2 ) :16 1 16 9.[WangDezi,ZhouJincheng .LookbackandLookforwardtograniteresearch .ActaPetrologicaSinica ,1999,15 (2 ) :16 1 16 9.
[1] 夏林圻 ,夏祖春 ,张诚 ,RClocchiatti,JDardel,JLJoron .相山中生代含铀火山杂岩岩石地球化学 .北京 :地质出版社 ,1992 .[XiaLingi,XiaZuchun ,ZhangCheng ,ClocchiattiR ,DardelJ,JoronJL .PetrogeochemistryofMesozoicuranifer ousvolcaniccomplexfromXiangshan ,China .Beijing :GeologicalPublishingHouse ,1992 .]
[2 ] 王德滋 ,刘昌实 ,沈渭洲 ,陈繁荣 .江西东乡 -相山中生代S型火山岩带的发现及其地质意义 .科学通报 ,1991,(19) :1491 1493 .[WangDezi,LiuChangshi,ShenWeizhou ,ChenFangrong .FindingoftheMesozicS typevolcanicrockzoneinDongxiang -XiangshanofJiangxianditsgeologicalsignificance.ChineseScienceBulletin ,1991,36 (19) :1491 1493.]
[3] 沈渭洲 ,陈繁荣 ,刘昌实 ,王德滋 .江西两类火山侵入杂岩的同位素地球化学特征和物质来源 .岩石学报 ,1992 ,8(2 ) :177 184.[ShenWeizhou ,ChenFangrong ,LiuChangshi,WangDezi.Characteristicsofisotopicgeochemistyandmaterialsourcesoftwotypesofvolcanic intrusivecomplexesinJiangxi.ActaPerologicalSinica ,1992 ,8(2 ) :177 184.]
[4 ] 方锡珩 ,侯文尧 ,万国良 .相山破火山口火山杂岩体的岩石学研究 .岩矿测试 ,1982 ,1(1) :2 9.[FangXiheng ,HouWenyao ,WanGouliang .PetrographicstudiesofthevolcaniccomplexintheXiangshanCaldera .ActaPetrologicalMiner alogicaetAnalytica ,1982 ,1(1) :1 10 .]
[5 ] 徐克勤 ,朱金初、刘昌实 ,沈渭洲 ,徐士进 .华南花岗岩类的成因系列和物质来源 .南京大学学报 (地球科学版 ) ,1989,3 :1 18.[XuKeqin ,ZhuJinchu ,LiuChangshi,ShenWeizhou ,XuShijing .ThegeneticseriesandmaterialsourcesofgranitoidsinSouthChina .JournalofNanjingUniversity(EarthSciencesEdition) ,1989,3 :1 18.]
[6 ] HendersonP ,ed .Rareearthelementgeochemistry .Amsterdam :Elsevier ,1984.
[7] 陈小明 ,陆建军 ,刘昌实 ,等 .桐庐、相山火山 -侵入杂岩单颗粒锆石U Pb年龄 .岩石学报 ,1999,15 (2 ) :2 72 2 78.[ChenXiaoming ,LuJianjun ,LiuChangshi,ZhaoLianze,WangDezi,LiHuimin .Single grainzirconU Pbisotopicagesofthevolcanic intrusivecomplexesinTongluandXiangshanareas.ActaPetrologicalSinica ,1999,15 (2 ) :2 72 2 78.]
[8] CastroA .etc .H type (hybrid) granitoid :aproposedrevisionofthegranite typeclassificationandnomenclature .EarthSeienceReviews,1991,31:2 37 2 5 3 .
[9] 梁良 ,刘成东 ,李建红 .相山火山岩成岩构造环境的地球化学判据 .江西地质 ,1993 ,7(4 ) :2 81 2 91.[LiangLiang ,LiuChengdong ,LiJianghong .GeochemicalintergretationofpetrogeneticstructureenvironmentofthevolcanicrocksinXi angshan .JiangxiGeology ,1993,7(4 ) :2 81 2 91.]
[10 ] 陈迪云 ,周文斌 ,吴伯林 .相山碎斑熔岩铷 -锶、氧、铅同位素地球化学研究 .南京大学学报 (地球科学版 ) ,1994,6 :45 5 0 .[ChengDiyun ,ZhouWengbing ,WuBolin .StudyonRb ,Sr,O ,andPbisotopicgeochemistryoftheXiangshanclastoporphyriticlava .JournalofNanjingUniversity(EarthSciencesEdition) ,1994,6 :45 5 0 .]
[11] 廖群安 ,李昌年 ,王京名 .江绍断裂带晚侏罗世S型火山岩特征及其地质意义 .地球科学 ,1999,2 4(1) :6 3 6 8.[LiaoQun’an ,LiChangnian ,WangJingming .CharacteristicsofS typevolcanicrocksoflateJurassicperiodinJiangshaofracturezoneandtheirgeologicalsignificance.Earth ,1999,2 4(1) :6 3 6 8.]
[12 ] HildenP .,HallidayAN ,StephensWE .Neodymiumandstrontiumisotopecontentofmicrodioriteenclavespointstoman tleinputtogranitoidproduction .Nature,1989,330 (5 ) :5 4 5 6 .
[13] 刘昌实 ,沈渭洲 ,熊小林 ,王德滋 .江西岩背火山 -侵入杂岩的微量元素协变关系及其岩浆成分分带形成机制的探讨 .岩石学报 ,1994,10 (2 ) :15 1 16 0 .[LiuChangshi,ShenWeizhou ,XiongXiaoling ,WangDezi.CovarianceplotsoftraceelementsanddiscussiononacompositionalzonationofmagmachambersforYanbeivolcanic intrusivecomplexinJiangxiProvince .ActaPetrologicaSinica ,1994,10 (2 ) :15 1 16 0 .]
[14] 杨浩 .论痕量元素协变关系的应用 .地质论评 ,1990 ,36 (1) :6 9 80 .[YangHao .Applicationoftraceelementcovari anceplots.GeologicalReview ,1990 ,36 (1) :6 9 80 .]
[15 ] 董传万 ,彭亚明 .浙江青田花岗岩中岩石包体特征及成因 .岩石矿物学杂志 ,1994,2 2 (1) :2 3 30 .[DongChuanwan ,PengYaming .ThefeaturesandoriginoftheenclavesintheQingtiangranite ,ZhejiangProvince.ActaPetrologicaetMin eralogica ,1992 ,11(1) :2 1 30 .]
[16 ] 徐夕生 ,周新民 .花岗岩类中的岩石包体 .南京大学学报 (地球科学版 ) ,1988,1:2 33 2 39.[XuXisheng ,ZhouXin min .Rockinclusionsingranitoids.JournalofNanjingUniversity (EarthSciencesEdition) ,1988,1:2 33 2 39.
[17] 周金城 ,徐夕生 ,等 .寄主花岗岩对微花岗岩类包体的地球化学制约 .地球化学 ,1994,3 :2 5 4 2 6 1.[ZhouJincheng ,XuXisheng ,TaoXiancong .Geochemicalconstraintsonmicrogranitoidenclavesbyhostgranites .Geochemica ,1994,2 3(3) :2 5 4 2 6 1.]
[18] 王德滋 ,周金城 .我国花岗岩研究的回顾与展望 .岩石学报 ,1999,15 (2 ) :16 1 16 9.[WangDezi,ZhouJincheng .LookbackandLookforwardtograniteresearch .ActaPetrologicaSinica ,1999,15 (2 ) :16 1 16 9.
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