沉积地层中火山沉积岩夹层中粘土矿物成因和成岩作用特征
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摘要
沉积岩地层序列中包含着火山沉积岩、熔岩和火山碎屑沉积岩内的粘土夹层。这类粘土矿物具有相对单一母岩物源成分。研究粘土矿物演化特点有利于标记岩石成岩作用环境。高分辨电镜和X-射线衍射分析结果证明,在玄武质火山沉积岩的杏仁体中,绿泥石结晶体中心形成一个核,在这个核心周围纤维状的蒙脱石晶体形成一个壳层。绿泥石晶体的生长方向和晶面的接触关系表明绿泥石的析出晚于壳层的纤维状蒙脱石晶体。作为母岩的火山沉积岩中蒙脱石和浊沸石的矿物共生组合表明岩石样品没有被成岩作用和低温热液变质作用影响。因此,杏仁体形成在岩浆冷却和早期成岩作用阶段,绿泥石和蒙脱石晶体组合受岩层内部流体演化控制。流体低SiO_2、相对高的FeO和Al_2O_3含量是绿泥石结晶析出的有利条件。
In stratigraphic sequence, volcanic lava beds are a kind of sedimentary rocks from a unique sediment source. The characteristics of the clay minerals show the environment of diagenetic process. In the basalt, the chlorite occurs in the center of basalt amygdales, as a core. There is a fibrous shell around the cores consisting of smectite determined by a high resolution transmission electron microscopy(HRTEM) and X-ray diffraction(XRD). The orientation of crystal growth and contacting surface of the minerals show that chlorite precipitates later than the smectite crystals of amygdaloidal shell layer in the volcanic sedimentary rock. The diagenetic degree of the volcanic sedimentary rock is characterized by smectite and analcime paragenetic association, which feature shows that the assemblage has not been altered by diagenesis and low grade hydrothermal metamorphism. In an amygdale, the smectite and chlorite assemblage were controlled by the chemical evolution of later environmental fluid from magma consolidation to early diagenetic stage. There are lower SiO_2, relatively high FeO and Al_2 O_3 concentration of the fluid to be favorable to chlorite crystallization in low temperature condition.
In stratigraphic sequence, volcanic lava beds are a kind of sedimentary rocks from a unique sediment source. The characteristics of the clay minerals show the environment of diagenetic process. In the basalt, the chlorite occurs in the center of basalt amygdales, as a core. There is a fibrous shell around the cores consisting of smectite determined by a high resolution transmission electron microscopy(HRTEM) and X-ray diffraction(XRD). The orientation of crystal growth and contacting surface of the minerals show that chlorite precipitates later than the smectite crystals of amygdaloidal shell layer in the volcanic sedimentary rock. The diagenetic degree of the volcanic sedimentary rock is characterized by smectite and analcime paragenetic association, which feature shows that the assemblage has not been altered by diagenesis and low grade hydrothermal metamorphism. In an amygdale, the smectite and chlorite assemblage were controlled by the chemical evolution of later environmental fluid from magma consolidation to early diagenetic stage. There are lower SiO_2, relatively high FeO and Al_2 O_3 concentration of the fluid to be favorable to chlorite crystallization in low temperature condition.
引文
[1]HOWER J,ESLINGER E V,HOWER M E,et al.Mechanism of burial metamorphism of alteration:1.Mineralogical and chemical evidence[J].Geol.Soc.of Ame.Bull.,1976(87):725-737.
[2]EBERL C H.Three zones for illite formation during burial diagenesis and metamorphism[J].Clays and Clay Minerals,1993(41):26-37.
[3]WEARER C E.“Authigenic Marine”physics.In developments in sedimentology 44:clays,muds,and shales[C].AMSTERDAM:WEARER C E,Elsevier,1989:345-414.
[4]SCHIFFMAN P,STAUDIGEL H.Hydrothermal alteration of a seamount complex on La Palma,Canary Islands:implications for metamphism in accreted terranes[J].Geology,1994(22):1 51-1 54.
[5]NIU B,YOSHIMURA T.Smectite conversion in Diagenesis and low grde hydrothermal alteration from Neogene basaltic marine sediments in Niigata basin,Japan[J].Clay Science,1997(10):37-56.
[6]KOBAYASHI I,TATEISHI M.Neogene stratigraphy and paleogeography in the Niigata region,Central Japan[J].Mem.Geol.Soc.Japan,1992(37):53-70.
[7]BLOSS F D.Crystallography and crystal chemistry[M].Washington D C:Mineralogical Society of America,1994:152-248.
[8]SUNAGAWA I.Nucleation,growth and dissolution of crystals during sedimentogenesis and diagenesis.Diagenesis,IV.Developments in Sedimentology,51[C].AMSTERDAM:WOLF KH,CHILINGGARIAN G V,Elsevier,1994:19-47.
[9]IIYAMA J T,ROY R.Controlled synthesis of heteropolytypic(mixed-layer)clay minerals[J].Clays and Clay Minerals,1963(10):4-22.
[10]ACKERSON B J,SCHATZEL K.Classical growth of hardsphere colloidal crystals[J].Phys.Rev,1995(52):6448-6460.
[11]SUTO T.The origin of lamellar textures encountered in concretions and related substance(II)-Processes,Mechanism,Agents[J].Nendo Kagaku(in Japanese),1997(36):196-209.
[12]ZHU J,LI M,ROGERS R,et al.Crystallization of hard sphere colloids in microgravity[J].Nature,1997(387):883-884.
[13]KURNOSOV V B,KHOLODKEVICH I V,LUDMILA P,et al.The origin of clay mineral in the oceanic crust revealed by natural and experimental data[C].Bologna:Pavia,Proc.Int.Clay Conf.,1981:547-556.
FeO*代表矿物含铁总量,即(FeO+Fe2O3)。
[2]EBERL C H.Three zones for illite formation during burial diagenesis and metamorphism[J].Clays and Clay Minerals,1993(41):26-37.
[3]WEARER C E.“Authigenic Marine”physics.In developments in sedimentology 44:clays,muds,and shales[C].AMSTERDAM:WEARER C E,Elsevier,1989:345-414.
[4]SCHIFFMAN P,STAUDIGEL H.Hydrothermal alteration of a seamount complex on La Palma,Canary Islands:implications for metamphism in accreted terranes[J].Geology,1994(22):1 51-1 54.
[5]NIU B,YOSHIMURA T.Smectite conversion in Diagenesis and low grde hydrothermal alteration from Neogene basaltic marine sediments in Niigata basin,Japan[J].Clay Science,1997(10):37-56.
[6]KOBAYASHI I,TATEISHI M.Neogene stratigraphy and paleogeography in the Niigata region,Central Japan[J].Mem.Geol.Soc.Japan,1992(37):53-70.
[7]BLOSS F D.Crystallography and crystal chemistry[M].Washington D C:Mineralogical Society of America,1994:152-248.
[8]SUNAGAWA I.Nucleation,growth and dissolution of crystals during sedimentogenesis and diagenesis.Diagenesis,IV.Developments in Sedimentology,51[C].AMSTERDAM:WOLF KH,CHILINGGARIAN G V,Elsevier,1994:19-47.
[9]IIYAMA J T,ROY R.Controlled synthesis of heteropolytypic(mixed-layer)clay minerals[J].Clays and Clay Minerals,1963(10):4-22.
[10]ACKERSON B J,SCHATZEL K.Classical growth of hardsphere colloidal crystals[J].Phys.Rev,1995(52):6448-6460.
[11]SUTO T.The origin of lamellar textures encountered in concretions and related substance(II)-Processes,Mechanism,Agents[J].Nendo Kagaku(in Japanese),1997(36):196-209.
[12]ZHU J,LI M,ROGERS R,et al.Crystallization of hard sphere colloids in microgravity[J].Nature,1997(387):883-884.
[13]KURNOSOV V B,KHOLODKEVICH I V,LUDMILA P,et al.The origin of clay mineral in the oceanic crust revealed by natural and experimental data[C].Bologna:Pavia,Proc.Int.Clay Conf.,1981:547-556.
FeO*代表矿物含铁总量,即(FeO+Fe2O3)。