...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Periodico di mineralogia >Crystallization from a melt and crystallization at subsolidus conditions: comparison from crystal size distribution study on Gennargentu Rocks (Sardinia, Italy)
【24h】

Crystallization from a melt and crystallization at subsolidus conditions: comparison from crystal size distribution study on Gennargentu Rocks (Sardinia, Italy)

机译：从熔体中结晶和在亚固相线条件下结晶：Gennargentu岩石（意大利撒丁岛）的晶体尺寸分布研究的比较

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Plagioclase crystal size distribution (CSD) has been investigated in a quartz-diorite body, in the leucosome of migmatites and in the melanosome of un-melted contact metamorphic rocks from Gennargentu Complex (Sardinia, Italy). During the crystallization of the dioritic magma, a variety of competing kinetic processes determine the evolution of the igneous microstructure, but the relative contribution of each process remains elusive. Our approach was aimed to study the plagioclase crystallization from a liquid (quartz-diorites and migmatite leucosomes), comparing it to a crystallization at subsolidus conditions. CSD indicates that plagioclase in the quartz-diorite nucleated and grew in a cooling system at a constant cooling rate, producing straight-line CSD in a diagram of In of population density vs. size range. The plagioclase crystallization continued until the latent heat was available and the temperature was high enough to allow the plagioclase growing. This can occur only when a crystal is held at temperature close to its liquidus for a long period of time. Under these conditions, the plagioclase nucleation rate is zero, but growth rate is high for crystal larger than the critical size. This does not necessarily mean that the temperature was held constant, just that the undercooling remained small (Ostwald ripening process). The aggregated small crystals, due to their high surface energy per unit volume, to minimise energy in the system dissolved and "fed" the growth of larger crystals. This process occurs because small grains have a higher surface energy per unit volume than do larger grains. The crystallization temperature (similar to 900 degrees C, 100 MPa) allows the formation of plagioclase as liquidus phase. From CSD measurements we calculated the different cooling ages for the different sample types.
机译：斜长石晶体大小分布（CSD）已在石英闪长岩体，辉锰矿的亮质体和Gennargentu Complex（意大利撒丁岛）的未熔融接触变质岩的黑素体中进行了研究。在闪长岩浆的结晶过程中，各种竞争的动力学过程决定了火成岩微观结构的演化，但是每个过程的相对作用仍然难以捉摸。我们的方法旨在研究液体中斜长石的结晶（石英-闪闪石和辉石辉石的脂质体），并将其与在固相线下的结晶进行比较。 CSD表示石英闪长岩中的斜长石在冷却系统中以恒定的冷却速率成核并生长，从而在人口密度与大小范围的In的关系图中生成直线CSD。斜长石的结晶持续进行直到潜热可用并且温度足够高以允许斜长石生长。仅当晶体长时间保持在接近其液相线的温度下时，才会发生这种情况。在这些条件下，斜长石成核速率为零，但对于大于临界尺寸的晶体，其生长速率很高。这并不一定意味着温度保持恒定，只是过冷度很小（奥斯特瓦尔德熟化过程）。聚集的小晶体由于其每单位体积的高表面能，使溶解在系统中的能量最小化，并“喂食”了大晶体的生长。之所以会发生此过程，是因为小晶粒每单位体积的表面能比大晶粒高。结晶温度（类似于900摄氏度，100兆帕）允许斜长石的形成为液相。通过CSD测量，我们计算出不同样品类型的不同冷却时间。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号