摘要
产于藏南拆离系内的钙质硅酸岩,由于强烈的剪切变形作用,表现为颜色丰富、对比强烈、细密平直的面理,外观类似不同颜色堆叠的绒布,具有较高的工艺应用前景和科研价值。其矿物组成为石英、长石、角闪石、黑云母、透辉石、绿帘石,还含有少量磷灰石、榍石、方解石、绿泥石、黄铁矿、锆石等副矿物。矿物颗粒多呈半自形状并伴随不同程度的定向、拉长,偶见后期自形较好的粒状晶体与穿插的长石、石英、方解石细脉。综合本文研究及相关文献,推测钙质硅酸岩形成的温压条件为:变质变形温度可达~630℃,变形期间的围岩压力约为0.2~0.5GPa;变质作用发生于25Ma左右,结束时间可至17~15Ma。钙质硅酸岩的形成过程:沉积成岩后,在流体参与下发生交代蚀变作用形成了钙质硅酸盐为主的矿物;随后受动力变质作用矿物发生重结晶形成了颜色丰富、面理平直的钙质硅酸岩层。不同颜色的细层主要为矿物分层分带所致,这一现象是在强烈的变质变形及重结晶作用下形成的。相应地,其构成了藏南拆离系十分重要的表现方式。正是在这种特殊的构造地质背景和多种作用下才形成了这种独特外观的硅酸岩。该钙质硅酸岩质地细腻、平均摩氏硬度为6,具有较高的工艺应用潜力。通过设计与雕刻应用的研究,表明其在艺术创作中兼具广阔的表现空间和独特的工艺特性,具有较好的开发价值。由于该岩石发现于珠峰麓下绒布寺附近的冰川冲沟,且具有绒布质感,故将其工艺名定为“绒布玉”,以期其能够助力促进藏区文化艺术品开发与旅游行业发展。此外,该研究还将有助于深入了解藏南拆离系,并从经济发展角度推动该钙质硅酸岩的合理利用。
The calcareous silicate rocks in the South Tibetan Detachment System(STDS)exhibit fine,planar foliations with rich and high contrast colors due to strong shear deformation,resembling stacked flannelette.These rocks possess high technological application prospects and scientific research value.Their mineral components primarily include quartz,feldspar,amphibole,biotite,diopside and epidote,with small amount of apatite,titanite,calcite,chlorite,pyrite and zircon.Most mineral particles are subhedral,exhibiting varying degrees of orientation and elongation,with occasional well-formed euhedral crystals and some interspersed veins of feldspar,quartz,and calcite.Based on this study and relevant literature,the formation conditions of these rocks are as follows:the metamorphic deformation temperature reaches approximately 630℃,and the surrounding pressure during deformation process is 0.2~0.5GPa.The metamorphic process began around 25Ma,and ended between 17~15Ma.Following sedimentation and diagenesis,fluid-induced alteration and replacement led to the formation of primarily calcium silicate minerals.Under dynamic metamorphism,these minerals underwent recrystallization,producing the colorful,planar foliated calcareous silicate layers.The fine layers with varying colors are primarily attributed to mineral stratification and zoning caused by such intensive metamorphic deformation and recrystallization.Correspondingly,it constitutes an important manifestation of the STDS.Such unique appearance of these silicate layers is a result of this distinct tectonic setting and multiple geological processes.This calcareous silicate rocks are fine with an average Mohs hardness of 6.Researches on its design and carving potential indicate that it is a material with significant creative potential and unique process performance,making it a promising candidate for development and application.As the rocks found in a glacial gully near the Rongbu Temple at the foot of Mount Qomolangma and possess a flannelette texture,they have been named“Rongbu Jade”,and the jade is expected to contribute to the application of cultural and artistic works,as well as the tourism industry in Tibet.Moreover,this study will enhance our understanding of the STDS and promote the rational utilization of these rock layers from the perspective of economic development.
作者
施光海
邓晴晴
梅玉林
林伟
姜鹏飞
翟寒蕾
路雪扬
佟星
SHI GuangHai;DENG QingQing;MEI YuLin;LIN Wei;JIANG PengFei;ZHAI HanLei;LU XueYang;TONG Xing(China University of Geosciences,Beijing 100083,China;Gems&Jewelry Trade Association of Liaoning,Shenyang 110032,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Gems&Jewelry Trade Association of China,Beijing 100010,China)
出处
《岩石学报》
北大核心
2025年第7期2525-2538,共14页
Acta Petrologica Sinica
基金
第二次青藏高原综合科学考察研究专题“资源能源现状与评估”课题(2019QZKK0802)资助.
关键词
藏南拆离系
钙质硅酸岩
“绒布玉”
岩石学特征
工艺性能
开发应用
South Tibetan Detachment System
Calcareous silicate rock
“Rongbu Jade”
Petrological characteristic
Process performance
Exploitation and application
