FLUID INCLUSION STUDIES OF EJECTED NODULES FROM PLINIAN ERUPTIONS OF MT SOMMA-VESUVIUS

被引:79
作者
BELKIN, HE [1 ]
DEVIVO, B [1 ]
机构
[1] UNIV NAPOLI FEDERICO II,DIPARTIMENTO GEOFIS & VULCANOL,I-80138 NAPLES,ITALY
关键词
D O I
10.1016/0377-0273(93)90103-X
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
Mt. Somma-Vesuvius (Naples, Italy) has erupted potassium-rich and silica-undersaturated products during a complicated history of plinian and non-plinian events. Coarse-grained cognate nodules are commonly found in the pyroclastics and are upper crustal in origin. We examined cumulate and subeffusive nodules from the 3800 y.B.P. Avellino, A.D. 79 Pompei, and A.D. 472 Pollena eruptions. Silicate-melt and liquid-vapor fluid inclusion studies in clinopyroxene from both types of nodules have been used to assess the fluids attending crystallization and to place constraints on the pressure and temperature of nodule formation. Thermometric and volumetric data from primary and pseudosecondary CO2-H2O and CO2 and coeval silicate-melt fluid inclusions indicate that they were trapped at a pressure of similar to 1 to similar to 2.5 kbar at similar to 1200 degrees C. This suggests a crystallization depth of similar to 4 to similar to 10 km. The H2O-bearing fluid inclusions are abundant from plinian eruptions in contrast to non-plinian eruptions where H2O-bearing fluid inclusions were rare. The presence of primary H2O-CO2 fluid inclusions indicates that an immiscible, supercritical H2O-CO2 fluid was in the nodule-forming environment. The H2O-bearing fluid inclusions in plinian nodules may record a higher pre-eruptive H2O content in the bulk magma that is dramatically reflected in the eruption dynamics.
引用
收藏
页码:89 / 100
页数:12
相关论文
共 32 条
[1]  
ARNO V, 1987, CNR QUAD RIC SCI, V8, P53
[2]  
Barberi F., 1981, B VOLCANOL, V44, P295, DOI DOI 10.1007/BF02600566
[3]  
BELKIN HE, 1985, AM MINERAL, V70, P288
[4]  
BELKIN HE, 1985, EJECTED NODULES 79 A
[5]   MIXING OF H2O-CO2 IN FLUID INCLUSIONS - GEOBAROMETRY AND ARCHEAN GOLD DEPOSITS [J].
BROWN, PE ;
LAMB, WM .
GEOCHIMICA ET COSMOCHIMICA ACTA, 1986, 50 (05) :847-852
[6]   MAGMA MIXING AND CONVECTIVE COMPOSITIONAL LAYERING WITHIN THE VESUVIUS MAGMA CHAMBER [J].
CIVETTA, L ;
GALATI, R ;
SANTACROCE, R .
BULLETIN OF VOLCANOLOGY, 1991, 53 (04) :287-300
[7]   GAS HYDRATES IN CO2-BEARING FLUID INCLUSIONS AND THE USE OF FREEZING DATA FOR ESTIMATION OF SALINITY [J].
COLLINS, PLF .
ECONOMIC GEOLOGY, 1979, 74 (06) :1435-1444
[8]   TRAPPING TEMPERATURES OF MELT INCLUSIONS FROM EJECTED VESUVIAN MAFIC XENOLITHS [J].
CORTINI, M ;
LIMA, A ;
DEVIVO, B .
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 1985, 26 (1-2) :167-172
[9]  
DEVIVO B, 1991, 1991 INT C ACT VOL R
[10]   PHLOGOPITE-CLINOPYROXENITE NODULES FROM HIGH-K MAGMAS, ROCCAMONFINA VOLCANO, ITALY - EVIDENCE FOR A LOW-PRESSURE METASOMATIC ORIGIN [J].
GIANNETTI, B ;
LUHR, JF .
EARTH AND PLANETARY SCIENCE LETTERS, 1990, 101 (2-4) :404-424