Lyubomirka Macheva, P. Machev, Julia Plotkina, Е.V. Salnikova, Maria Stifeeva
{"title":"斯雷德纳戈拉山脉蚀变岩的 Sm-Nd 年龄测定--HP 变质事件还是最终逆退","authors":"Lyubomirka Macheva, P. Machev, Julia Plotkina, Е.V. Salnikova, Maria Stifeeva","doi":"10.52215/rev.bgs.2023.84.2.57","DOIUrl":null,"url":null,"abstract":"The eclogites from Sredna Gora Mts. occur as small isolated bodies enclosed in amphibolites, two-mica schists and migmatized gneisses. They have tholeiitic composition and characteristics of MOR basalts. Three equilibrium mineral associations are distinguished in eclogites: (1) high-pressure (HP) – Grt+CPx(Omp)+Zo+Rt; (2) middle-pressure-high temperature (MP/HT) – Opx+CPx+Pl and middle pressure – middle temperature (MP/MT) presented by Amp+Pl+Qzt+Ep+Ilm+Ttn. The P-T conditions of HP stage reached values of 1.6–2.02 GPa and 650–690 °С. After the HP stage and CPx-Pl symplectite formation, the eclogites underwent a short-lived granulite facies overprint under temperatures similar to those of the HP event. The P-T conditions of the retrograde amphibolite facies overprint are in the range 620–650 °C and 0.6–0.8 GPa. The obtained age of 319±28 Ma by Sm-Nd garnet+whole rock method is interpreted as age of the final retrograde metamorphism under P-T conditions of high temperature amphibolite facies.","PeriodicalId":509487,"journal":{"name":"Review of the Bulgarian Geological Society","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Sm-Nd age determination of eclogites from Sredna Gora Mountains – HP metamorphic event or final retrogression\",\"authors\":\"Lyubomirka Macheva, P. Machev, Julia Plotkina, Е.V. Salnikova, Maria Stifeeva\",\"doi\":\"10.52215/rev.bgs.2023.84.2.57\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"The eclogites from Sredna Gora Mts. occur as small isolated bodies enclosed in amphibolites, two-mica schists and migmatized gneisses. They have tholeiitic composition and characteristics of MOR basalts. Three equilibrium mineral associations are distinguished in eclogites: (1) high-pressure (HP) – Grt+CPx(Omp)+Zo+Rt; (2) middle-pressure-high temperature (MP/HT) – Opx+CPx+Pl and middle pressure – middle temperature (MP/MT) presented by Amp+Pl+Qzt+Ep+Ilm+Ttn. The P-T conditions of HP stage reached values of 1.6–2.02 GPa and 650–690 °С. After the HP stage and CPx-Pl symplectite formation, the eclogites underwent a short-lived granulite facies overprint under temperatures similar to those of the HP event. The P-T conditions of the retrograde amphibolite facies overprint are in the range 620–650 °C and 0.6–0.8 GPa. The obtained age of 319±28 Ma by Sm-Nd garnet+whole rock method is interpreted as age of the final retrograde metamorphism under P-T conditions of high temperature amphibolite facies.\",\"PeriodicalId\":509487,\"journal\":{\"name\":\"Review of the Bulgarian Geological Society\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2023-11-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Review of the Bulgarian Geological Society\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.52215/rev.bgs.2023.84.2.57\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Review of the Bulgarian Geological Society","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.52215/rev.bgs.2023.84.2.57","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Sm-Nd age determination of eclogites from Sredna Gora Mountains – HP metamorphic event or final retrogression
The eclogites from Sredna Gora Mts. occur as small isolated bodies enclosed in amphibolites, two-mica schists and migmatized gneisses. They have tholeiitic composition and characteristics of MOR basalts. Three equilibrium mineral associations are distinguished in eclogites: (1) high-pressure (HP) – Grt+CPx(Omp)+Zo+Rt; (2) middle-pressure-high temperature (MP/HT) – Opx+CPx+Pl and middle pressure – middle temperature (MP/MT) presented by Amp+Pl+Qzt+Ep+Ilm+Ttn. The P-T conditions of HP stage reached values of 1.6–2.02 GPa and 650–690 °С. After the HP stage and CPx-Pl symplectite formation, the eclogites underwent a short-lived granulite facies overprint under temperatures similar to those of the HP event. The P-T conditions of the retrograde amphibolite facies overprint are in the range 620–650 °C and 0.6–0.8 GPa. The obtained age of 319±28 Ma by Sm-Nd garnet+whole rock method is interpreted as age of the final retrograde metamorphism under P-T conditions of high temperature amphibolite facies.
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