Geothermobarometry in metasediments of the southern Grossvenediger area (Tauern Window, Austria)
Geothermobarometry in metasediments of the southern Grossvenediger area (Tauern Window, Austria)
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Grossvenediger 地区南部变沉积岩的地温气压测量（奥地利 Tauern Window）
DOI：
10.1111/j.1525-1314.1990.tb00467.x
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发表时间：
1990
影响因子：
3.4
通讯作者：
E. Dachs
中科院分区：
文献类型：
--
作者：
E. Dachs
对南Grossvenediger地区（奥地利Tauern Window）的变质沉积物进行了研究，研究方向为沿着一个从南部Tauern Window边缘到北部上Schieferhulle基底（包括Eclopathic带）的变质等级递增的岩石剖面。
在剖面的南部，没有高压遗迹或假像形式的前晚期阿尔卑斯变质历史的证据。矿物组合以透闪石+方解石、黑云母+方解石和黑云母+方解石+方解石的稳定性为特征。在北方部分，保存了更完整的阿尔卑斯变质演化。原生高压组合为白云岩+石英、透闪石+锆石、锆石+白云岩+石英+多硅白云母I和可能的透闪石+白云岩+多硅白云母I。次级运动学后组合[透闪石+方解石、滑石+方解石、多硅白云母II +方解石+方解石（+石英）、黑云母+方解石+方解石、黑云母+黝帘石+方解石]是由晚期阿尔卑斯变质叠加作用形成的。黑云母+黝帘石+方解石的产状仅限于最北部地区，并定义了一个黑云母-黝帘石-方解石等梯度线。
基于标准温压技术和透闪石+方解石+白云石+石英和石英稳定性关系的P-T估计给出了一致的结果。剖面北方主要第三纪变质叠加的P-T条件为525° C，P= 7.5 ± 1 kbar。南部在430-470° C的低温下变质。该地区多硅白云母的硅含量几乎与榴辉岩带的多硅白云母一样高（Simax= 3.4 pfu）。根据Massone和Schreyer（1987），多硅白云母气压计建议在420° C时压力> 10千巴。在没有高压遗迹或假像的情况下，这些多硅白云母缺乏晚期阿尔卑斯再平衡作用，是南部岩石可能也经历了早期非榴辉岩高压变质作用的唯一记录。
Metasediments in the southern Grossvenediger area (Tauern Window, Austria) were studied along a cross-section through rocks of increasing metamorphic grade from the margin of the Tauern Window in the south to the base of the Upper Schieferhulle, including the Eclogite Zone, in the north.
In the southern part of the cross-section there is no evidence for a pre-late Alpine metamorphic history in the form of high-pressure relics or pseudomorphs. Mineral assemblages are characterized by the stability of tremolite + calcite, biotite + calcite and biotite + chlorite + calcite. In the northern part a more complete Alpine metamorphic evolution is preserved. Primary high-pressure assemblages are dolomite + quartz, tremolite + zoisite, zoisite + dolomite + quartz + phengite I and probably tremolite + dolomite + phengite I. Secondary, post-kinematic assemblages [tremolite + calcite, talc + calcite, phengite II + chlorite + calcite (+ quartz), biotite + chlorite + calcite, biotite + zoisite + calcite] formed as a result of the dominant late Alpine metamorphic overprint. The occurrence of biotite + zoisite + calcite is confined to the northernmost area and defines a biotite–zoisite–calcite isograd.
P–T estimates based on standard thermobarometric techniques and on stability relationships of tremolite + calcite + dolomite + quartz and zoisite give consistent results. P–T conditions of the main Tertiary metamorphic overprint were 525° C, P= 7.5 ± 1 kbar in the northern part of the cross-section. The southern part was metamorphosed at lower temperatures of 430–470° C. The Si-content of phengites from this area is almost as high as that of phengites from the Eclogite Zone (Simax= 3.4 pfu). Pressures > 10 kbar at 420° C are suggested by phengite barometry according to Massone & Schreyer (1987). In the absence of high-pressure relics or pseudomorphs, these phengites, which lack late Alpine re-equilibration, are the only record that rocks of the southern part probably also experienced an early non-eclogitic high-pressure metamorphism.