報告書番号

U86021

タイトル（和文）

電子スピン共鳴（ＥＳＲ）年代測定法による熱履歴の検討－黒部祖母谷変質帯における検討－

タイトル（英文）

INVESTIGATIONS ON THE GEOTHERMAL HISTORY OF THE ALTERATION ZONE BY ESR DATING METHOD-KUROBE BABADANI GEOTHERMAL ALTERATION ZONE-

概要 （図表や脚注は「報告書全文」に掲載しております）

黒部祖母谷変質帯の熱履歴について，石英粒子を対象とした，電子スピン共鳴（ＥＳＲ）年代測定法により検討を行った。測定した試料は，未照射でＥＳＲ信号の認められないタイプと複数のＥＳＲ信号の認められるタイプとに区分される。検出された信号の熱アニーリング特性から，任意の地熱温度における各信号の寿命を求めた。ＥＳＲ信号の出現の様式タイプの違いと，仮定した地熱温度における，信号の寿命の検討により，本変質帯には，年代の異なる２つの地熱活動が認められることを明らかにした。

概要 （英文）

GEOTHERMAL HISTORY OF THE KUROBEBABADANI GEOTHERMAL ALTERATION ZONE IS INVESIGATED BY ELECTRON SPIN RESONANCE (ESR)DATING METHOD USING QUARTZ GRAINS SEPARATED FROM ALTERATION ZONES. THEBABADANI ALTERATION ZONE IS COMPOSED OF QUARTZDIORITE,TERRACE DEPOSIT,TALUS DEPOSIT AND RIVER BED DEPOSIT. SAMPLES MESURED BY ESR ARE DEVIDEDINTO TWO TYPES NAMED A TYPE AND B TYPE. A TYPE IS CHARACTERIZED BY NO ESR SIGNALS IN PRE-ARTIFICIAL NU -RAY IRRADIATION SAMPLES. B TYPE IS CHARACTERIZED BY ONE OR SEVERAL SIGNALS IN PRE-ARTIFICIAL NU-RAY IRRADIATION ONES. A TYPE IS HEAVILY ALTERD CLAYEY QUARZTADIORITE AND A PART OF TRRACE DEPOSITS. B TYPE IS FRESH QUARTZDIORITE,TALUS DEPOSIT AND TERRACE DEPOSIT AT WHICH HYDROTHERMAL ACTIVITY IS RECOGNIZED NOW. THERMAL ANNEALING EXPERIMENTS ARE CARRIED OUT IN ODER TO DETERMINE THE LIFE TIME OF DEFECTS WITH ESR SIGNALS AT G=2.011(G-1) AND G=1.997(G-2). G-1 IS ANNEALED AT 360 DEGREE AND G-2 IS ANNEALED AT 320 DEGREE. AS A RESULT OF X-RAY ANALYSIS,ALTERED QUARTZADIORITE IS CHARACTERIZED BY ALUNITE. HEAVILY ALTERED CLAYEY ONE IS CHARACTERIZED BY KAOLINITE AND MONTMORILONITE.WEAKLY ALTERED SAMPLES ARE CHARACTERIZED BY SERICITE AND CHLORITE. ON THE ASSUMPTION THAT GEOTHERMAL TEMPERATURE HAS BEEN 80 DEGREE,A LIFE TIME OF DEFECTS WITH ESR SIGNAL G-1 IS 10 YEARS ORDER AND THAT G-2 IS 10 CUBED YEARS ORDER BY THE USE OF IKEYA S FIGURE (1983) AND THEN THE THERMAL HISTORY OF THE KUROBE BABADANI GEOTHERMAL ALTERATION ZONE IS SUGGESTED AS FOLLOWS. FIRST GEOTHERMAL ACTIVITY WITH ACID NEUTRAL OCCURRED 10CUBED YEARS ORDER BEFORE AT QUARTZ DIORTITE AND HAS CONTINUED UNTIL QUITE RECENTLY. AND THEN,AT THE TIME FROM 10 YEARS ORDER TO 10 CUBED YEARS ORDER BFORE,SECOND GEOTHERMAL ACTIVITY HAS OCCURRED IN TERRACE DEPOSITS AND HAS CONTINUED TO RECENT.

報告者

キーワード