The role of Fe content on the Fe-Mg exchange reaction in augite
The role of Fe content on the Fe-Mg exchange reaction in augite
复制标题
Fe含量对辉石中Fe-Mg交换反应的影响
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
M. Alvaro
中科院分区：
文献类型：
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作者：
M. Murri;L. Scandolo;A. Fioretti;F. Nestola;C. Domeneghetti;M. Alvaro
摘要对不同地质背景下单斜辉石中M1和M2晶位间的晶内Fe-Mg交换作用的研究，为认识含辉石岩石的热历史提供了一个框架。铁镁交换反应已被成功地用作研究斜方辉石和含木豆石岩石的地热工具，但单斜辉石的数据相对较少。一个强的相关性之间的总铁含量和斜率的Fe 2 +-Mg平衡分配系数（kD）作为温度的函数已被发现的斜方辉石和褐变岩，我们调查这种关系在普通辉石。我们在800、900和1000 °C下进行了新的平衡退火实验，随后进行了单晶X射线衍射和结构修正，以获得来自加拿大安大略120 m厚熔岩流的普通辉石的新的地质温度校准[Theo's Flow，En 49 Fs 9 Wo 42在下文中也称为Fs 9，其中Fs = 100·Fe/（Fe+Mg+Ca），其中Fe = Fe 2 ++ Fe 3 ++Mn]。这种新的校准使我们能够评估的组成的影响（主要是铁含量）与以前获得的数据从MIL 03346火星样品的辉石（En 36 Fs 24 Wo 40以下简称为Fs 24）进行比较。在Theo流量和米勒范围（MIL 03346）普通辉石上获得的数据之间观察到的非常好的一致性表明，对于Fs 9和Fs 24之间的组成范围，总铁含量对平衡行为具有可忽略的或零的影响。此外，来自Theo的Flow和MIL 03346的数据的线性回归给出了单个校准方程：lnkD = -4040（±180）/T（K）+1.12（±0.17）（R2 = 0.988）。这种新的标定描述了普通辉石的平衡行为，并可以可靠地用于确定普通辉石的闭合温度（Tc）的组成范围在Fs 9和Fs 24之间。
Abstract The study of the intracrystalline Fe-Mg exchange between M1 and M2 crystallographic sites in clinopyroxene on samples a variety of geological settings has provided a framework to understand the thermal history of pyroxene-bearing rocks. The Fe-Mg exchange reaction has successfully been exploited as a geothermometric tool in the study of orthopyroxene and pigeonite-bearing rocks, but relatively few data are available for clinopyroxene. A strong correlation between total iron content and the slope of the Fe2+-Mg equilibrium distribution coeffcient (kD) as a function of temperature has been found for orthopyroxene and pigeonite, and we investigate this relationship in augite. We carried out new equilibrium annealing experiments at 800, 900, and 1000 °C followed by single-crystal X-ray diffraction and structural refnement to obtain a new geothermometric calibration for augite from a 120 m thick lava fow from Ontario, Canada [Theo’s Flow, En49Fs9Wo42 hereafter also referred as Fs9 where Fs = 100·ΣFe/(ΣFe+Mg+Ca) with ΣFe = Fe2++Fe3++Mn]. This new calibration enabled us to evaluate the compositional effects (mainly Fe content) by comparison with the data previously obtained on augite from MIL 03346 martian sample (En36Fs24Wo40 hereafter referred to as Fs24). The extremely good agreement observed between the data obtained on Theo’s Flow and Miller Range (MIL 03346) augite demonstrate that for the range of compositions between Fs9 and Fs24, total iron content has a negligible or null infuence on equilibrium behavior. Furthermore, linear regression of data from Theo’s Flow and MIL 03346 gave a single calibration equation: lnkD = –4040(±180)/T(K) + 1.12(±0.17) (R2 = 0.988). This new calibration describes the equilibrium behavior of augite and can be reliably used to determine the closure temperature (Tc) of augite with composition ranging between Fs9 and Fs24.
DOI：
10.1107/s0108767394005726
发表时间：
1995-01-01
期刊：
ACTA CRYSTALLOGRAPHICA SECTION A
影响因子：
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作者：
BLESSING, RH
通讯作者：
BLESSING, RH