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首页> 外文期刊>Contributions to Mineralogy and Petrology >Pink manganian phengite in a high P/T meta-conglomerate from northern Syros (Cyclades, Greece)
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Pink manganian phengite in a high P/T meta-conglomerate from northern Syros (Cyclades, Greece)

机译：来自北部锡罗斯（希腊基克拉泽斯）的高P / T巨型砾岩中的粉红色锰质亚硫铁矿

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A new occurrence of Mn-rich rocks was discovered within the high-pressure/low-temperature metamorphic rocks on the Palos peninsula of Syros (Greece). Near the summit of Mount Príonas, a meta-conglomerate consists of calcite (~63 wt%), pink manganian phengite, blue–purple manganian aegirine–jadeite, microcline, albite and quartz. In addition, it contains abundant braunite-rich aggregates (up to ~1.5 cm in diameter) that include hollandite [(Ba0.98–1.02K<0.01Na<0.02Ca<0.03) (Mn 1.02–1.52 3+ Fe 0.38–0.88 3+ Ti0.29–0.92Mn 5.11–5.76 4+ )O16], barite and manganian hematite. Due to metamorphic recrystallization and deformation, the contacts between clasts and matrix are blurred and most clasts have lost their identity. In back-scattered electron images, many aegirine–jadeite grains appear patchy and show variable jadeite contents (Jd10–67). These pyroxenes occur in contact with either quartz or albite. Manganian phengite (3.41–3.49 Si per 11 oxygen anions) is of the 3T type and contains 1.4–2.2 wt% of Mn2O3. At the known P–T conditions of high-pressure metamorphism on Syros (~1.4 GPa/ 470 °C), the mineral sub-assemblage braunite + quartz + calcite (former aragonite) suggests high oxygen fugacities relative to the HM buffer (+7 ≤ ∆fO2 ≤ + 17) and relatively high CO2 fugacities. The exact origin of the conglomerate is not known, but it is assumed that the Fe–Mn-rich and the calcite-rich particles originated from different sources. Braunite has rather low contents of Cu (~0.19 wt%) and the concentrations of Co, Ni and Zn are less than 0.09 wt%. Hollandite shows even lower concentrations of these elements. Furthermore, the bulk-rock compositions of two samples are characterized by low contents of Cu, Co and Ni, suggesting a hydrothermal origin of the manganese ore. Most likely, these Fe–Mn–Si oxyhydroxide deposits consisted of ferrihydrite, todorokite, birnessite, amorphous silica (opal-A) and nontronite. Al/(Al + Fe + Mn) ratios of 0.355 and 0.600 suggest the presence of an aluminosilicate detrital component.
机译：在锡罗斯（希腊）的帕洛斯半岛的高压/低温变质岩中发现了新的富锰岩石。在Príonas山山顶附近，是由方解石（〜63 wt％），粉红色锰辉石，蓝紫色锰a精-翡翠，微晶，钠长石和石英组成的大集团。此外，它还含有丰富的富含褐铁矿的骨料（直径最大约1.5厘米），其中包括钙锌矿[[Ba0.98–1.02K <0.01Na <0.02Ca <0.03）（Mn 1.02–1.52 3+ Fe 0.38–0.88 3+ Ti0.29-0.92Mn 5.11-5.76 4+）O16]，重晶石和锰赤铁矿。由于变质的再结晶和变形，碎屑与基体之间的接触变得模糊，大多数碎屑失去了身份。在背向散射电子图像中，许多Aegirine-Jadeite晶粒出现斑片，并显示出变化的硬玉含量（Jd10-67）。这些辉石与石英或钠长石接触。锰次方铁矿（每11个氧阴离子为3.41–3.49 Si）是3T型的，并且含有1.4–2.2 wt％的Mn2O3。在锡罗斯（Syros）高压变质的已知P–T条件（〜1.4 GPa / 470°C）下，矿物子组合的褐铁矿+石英+方解石（前文石）表明相对于HM缓冲液（+7）具有高的氧逸散度≤∆fO2≤+ 17）和较高的CO2逸度。团块的确切来源尚不清楚，但可以假定富含Fe-Mn和富含方解石的颗粒来自不同的来源。褐铁矿的铜含量较低（〜0.19 wt％），而Co，Ni和Zn的含量小于0.09 wt％。锰铁矿显示这些元素的浓度更低。此外，两个样品的块状岩石成分的特征在于铜，钴和镍的含量低，表明锰矿的热成因。这些Fe–Mn–Si羟基氧化物沉积物最有可能由三水铁矿，钙锰矿，水钠锰矿，无定形二氧化硅（蛋白石A）和绿脱石组成。 Al /（Al + Fe + Mn）比率为0.355和0.600表明存在铝硅酸盐碎屑组分。

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