Fluid-assisted fracturing, cataclasis, and resulting plastic flow in mylonites from the Moresby Seamount detachment, Woodlark Basin
Fluid-assisted fracturing, cataclasis, and resulting plastic flow in mylonites from the Moresby Seamount detachment, Woodlark Basin
复制标题
伍德拉克盆地莫尔兹比海山脱离的糜棱岩中的流体辅助压裂、碎裂和由此产生的塑性流动
DOI：
10.1016/j.jsg.2013.10.001
复制
发表时间：
2013
影响因子：
3.1
通讯作者：
F. Heidelbach
中科院分区：
文献类型：
--
作者：
R. Speckbacher;M. Stipp;J.H. Behrmann ;F. Heidelbach
伍德拉克盆地（巴布亚新几内亚近海）的莫尔斯比海山拆离体（MSD）是一个大型活动低角度拆离体，出露于海底，并穿过基性变质岩。在碎裂变形过程中，石英的热液渗透和方解石的热液渗透都发生在碎裂变形中。这些先验的较软的矿物的后续变形导致在MSD中形成糜棱岩。本研究的目的是为了更好地理解从碎裂到塑性流动的变形机制转换。利用光学显微镜对断层岩的变形组构进行了分析。绘制流变临界相以确定分布和面积比例，并使用EBSD测量晶体学择优取向（CPO）。强方解石CPO表明位错蠕变占主导地位。然而，石英CPO较弱，更难以解释，这表明至少有一些应变调节扩散蠕变机制。当石英集合体与多矿物糜棱岩基质混合时，扩散蠕变晶界滑动可能占主导地位。由热液过程引起的从镁铁质碎裂岩到硅质和碳质糜棱岩的同构造转换是一种关键的弱化机制，使MSD在低剪切应力下至少能够间歇性地塑性流动。这可能是在水化和以镁铁质为主的地壳中进行低角度Determination的关键过程。
The Moresby Seamount detachment (MSD) in the Woodlark Basin (offshore Papua New Guinea) is a large active low-angle detachment excellently exposed at the seafloor, and cutting through mafic metamorphic rocks. Hydrothermal infiltration of quartz followed by that of calcite occurred during cataclastic deformation. Subsequent deformation of these a priori softer minerals leads to mylonite formation in the MSD. This study aims at a better understanding of the deformation mechanism switch from cataclastic to plastic flow. Deformation fabrics of the fault rocks were analyzed by light-optical microscopy. Rheologically critical phases were mapped to determine distributions and area proportions, and EBSD was used to measure crystallographic preferred orientation (CPO). Strong calcite CPOs indicate dominant dislocation creep. Quartz CPOs, however, are weak and more difficult to interpret, suggesting at least some strain accommodation by diffusion creep mechanisms. When quartz aggregates are intermixed with the polymineralic mylonite matrix diffusion creep grain boundary sliding may be dominant. The syntectonic conversion from mafic cataclasites to more siliceous and carbonaceous mylonites induced by hydrothermal processes is a critical weakening mechanism enabling the MSD to at least intermittently plastic flow at low shear stresses. This is probably a crucial process for the operation of low-angle detachments in hydrated and dominantly mafic crust.
登录
查看更多内容
影响因子：
3.1
作者：
L. Keller;M. Stipp
通讯作者：
L. Keller;M. Stipp
SP-糜棱岩：一些糜棱岩的超塑性流成因
DOI：
--
发表时间：
1975
期刊：
影响因子：
--
作者：
A. Boullier;Y. Guéguen
通讯作者：
Y. Guéguen
DOI：
--
发表时间：
1987
期刊：
影响因子：
--
作者：
P. Jordan
通讯作者：
P. Jordan
变形机制和流变学：为什么大理石比石英岩弱
影响因子：
2.7
作者：
K. Brodie;E. Rutter
通讯作者：
E. Rutter
影响因子：
2.9
作者：
H. Stünitz;J. Gerald
通讯作者：
H. Stünitz;J. Gerald