Lithos ( IF 2.9 ) Pub Date : 2021-04-24 , DOI: 10.1016/j.lithos.2021.106184 Dražen Balen , Hans-Joachim Massonne
The Inner Dinarides, a part of the Alpine-Dinaride mountain chain in south-eastern Europe, are known for extended ophiolite-derived ultramafic massifs. The sampled rocks from the metamorphic sole of such a massif, the Jurassic Krivaja-Konjuh ultramafic massif in central Bosnia and Herzegovina, are mainly garnet amphibolites, with large grains of pyrope-almandine garnet commonly surrounded by kelyphite coronae, and pargasite amphibolites. The bulk-rock geochemistry points to mantle peridotite as the protolith for pargasite amphibolite and N-MORB for garnet amphibolite. Pressure-temperature (P-T) pseudosections were constructed in the MnNCKFMASHTO system and contoured by isopleths for the modal and chemical composition of minerals. On this basis, a counterclockwise P-T path with maximum P-T conditions of 1.2 GPa and 960 °C was deduced for pargasite amphibolite as a bottom part of an overriding plate. This part was cooled by subducting oceanic crust. In addition, the Jurassic intra-oceanic subduction enabled infiltration of hydrous fluid necessary to form the pargasite amphibolites. A clockwise P-T path with maximum pressure conditions at ca. 2.1 GPa (ca. 65–70 km depth) and temperatures of 810 °C was reconstructed for garnet amphibolite from an upper part of the subducting plate which was exhumed in a subduction channel and came in contact with the pargasite amphibolite. Thus, these amphibolites formed before they were involved in a metamorphic sole at the interface between continental crust and obducting ophiolite.
中文翻译:
迪纳里德蛇绿岩带(克里瓦哈-孔朱超镁铁质断层带,中波斯尼亚和黑塞哥维那)的变质唯一闪石的两条相反的PT路径及其地球动力学意义
Inner Dinarides是欧洲东南部Alpine-Dinaride山脉的一部分,以延生蛇绿岩衍生的超镁铁质岩块而闻名。从这样的地块的变质岩底(波斯尼亚和黑塞哥维那中部的侏罗纪Krivaja-Konjuh超镁铁质地块)中取样的岩石主要是石榴石角闪石,其中大颗粒的火石-金刚烷石榴石通常被kelyphite电晕和石辉石闪石包围。块状岩石地球化学表明,地幔橄榄岩是辉石角闪石的原型,而N-MORB是石榴石角闪石的原型。在MnNCKFMASHTO系统中构造了压力-温度(PT)伪剖面,并用等值线勾勒出矿物的模态和化学成分。在此基础上,逆时针PT路径的最大PT条件为1。推算出辉绿石闪石为上覆板的底部,为2 GPa和960°C。这部分被俯冲的洋壳冷却了。另外,侏罗纪大洋内俯冲作用使形成辉石闪石的必要含水流体渗入。顺时针PT路径的最大压力条件约为。从俯冲板上部的俯冲板中重建出石榴石闪石的2.1 GPa(大约65-70 km的深度)和810°C的温度,该俯冲板在俯冲通道中被掘出并与顺滑石闪石接触。因此,这些角闪石在它们进入陆壳与引水蛇绿岩之间的界面的变质岩底之前就形成了。侏罗纪的大洋俯冲作用使渗透水形成了辉石闪石。顺时针PT路径的最大压力条件约为。从俯冲板上部的俯冲板中重建出石榴石闪石的2.1 GPa(大约65-70 km的深度)和810°C的温度,该俯冲板在俯冲通道中被掘出并与顺滑石闪石接触。因此,这些角闪石在它们进入陆壳与引水蛇绿岩之间的界面的变质底中之前就形成了。侏罗纪的大洋俯冲作用使水渗入形成辉石闪石的必要条件。顺时针PT路径的最大压力条件约为。从俯冲板上部的俯冲板中重建出石榴石闪石的2.1 GPa(大约65-70 km的深度)和810°C的温度,该俯冲板在俯冲通道中被掘出并与顺滑石闪石接触。因此,这些角闪石在它们进入陆壳与引水蛇绿岩之间的界面的变质底中之前就形成了。从俯冲板上部的俯冲板中重建出石榴石闪石的温度和深度为65–70 km,温度为810°C,该俯冲板在俯冲通道中被掘出并与辉石闪石接触。因此,这些角闪石在它们进入陆壳与引水蛇绿岩之间的界面的变质底中之前就形成了。从俯冲板上部的俯冲板中重建出石榴石闪石的温度和深度为65–70 km,温度为810°C,该俯冲板在俯冲通道中被掘出并与辉石闪石接触。因此,这些角闪石在它们进入陆壳与引水蛇绿岩之间的界面的变质底中之前就形成了。