Analysis of partial melting reactions of pelitic and basic metamorphic rocks of the Hidaka metamorphic belt.

通过1995、1996、1997三年的研究，取得了以下成果：1.日高变质岩是在绿片岩相-麻粒岩相条件下，经递进变质作用形成的。利用多种地质温度计和地质压力计估算了其压力和温度条件为450 ℃、0.2 ~ 900 ℃、0.5MPa。根据K-Ar测年数据，估计变质作用的年龄为56-40 Ma（始新世）。2.日高变质带泥质和基性变质岩的白质是这些岩石部分熔融形成的熔融物的凝固部分。日高变质带的泥质和基性变质岩的白质是这些岩石部分熔融形成的熔融物的凝固部分。另一方面，黑素体是部分熔融的残留物。3.麻粒岩相泥质岩的部分熔融反应（D带和E带）：1.3黑云母+4.6钾长石+78.3斜长石+ H_2O = 100熔体+3.2硅线石+191石英（D区），13.4黑云母+8.6斜长石+15.6石英+16.9硅线石= 100熔体+13.7钾长石+10.8堇青石（E区）.4.基性岩的部分熔融反应用等离子体法计算的麻粒岩相（E带）的角闪岩混合岩（斜长角闪岩）如下：0.77角闪石+10.00斜长石+0.01褐铁矿= 0.04磁铁矿+10.98+熔体（在区域E的较低温度部分），1.85角闪岩+10.00斜长石+0.00钛铁矿+12.54石英= 0.01磁铁矿+23.96熔体+单斜辉石5.基性变质岩的原岩为N-MORB成分的玄武岩。

Following results have been obtained by the three-year research (1995,1996 and 1997) supported by this grant.1.The Hidaka metamorphic rocks were formed by progressive metamorphism under the conditions of the greenschist facies to the granulite facies. The pressure and temperature conditions are estimated to have been 450ﾟC,0.2 MPa to 900ﾟC,0.5 MPa by means of several kinds of geothermometor and geobarometor. The age of the metamorphism are estimated to have been 56-40 Ma (Eocene) on the basis of data of K-Ar dating.2.Leucosome of pelitic and basic metamorphic rocks of the Hidaka metamorphic belt is solidified parts of melt formed by partial melting of these rocks. On the other hand, melanosome is residue of partial melting.3.Partial melting reactions of pelitic rocks of the granulite facies (zoneD and zone E) are as follow :1.3 biotite + 4.6 K-feldspar + 78.3 plagioclase + H_2O = 100 melt + 3.2 sillimanite + 191 quartz (in zone D),13.4 biotite + 8.6 plagioclase + 15.6 quartz + 16.9 sillimanite = 100 melt + 13.7 K-feldspar + 10.8 cordierite (in zone E).4.Partial melting reactions of basic rocks (amphibolite migmatites) of the granulite facies (zone E) calculated by the isocon method are as follow :0.77 hornblende + 10.00 plagioclase + 0.01 limenite = 0.04 magnetite + 10.98 + melt (in the lower temperature part of zone E),1.85 hornblende + 10.00 plagioclase + 0.0.ilmenite + 12.54 quartz = 0.01 magnetite + 23.96 melt + clinopyroxene (in the higher temperature part of zone E).5.Protolith of basic metamorphic rocks is basalt of N-MORB compositions.