The Fontaine Pluton: An early Ross Orogeny calc‐alkaline gabbro from southern Victoria Land, Antarctica
The Fontaine Pluton: An early Ross Orogeny calc‐alkaline gabbro from southern Victoria Land, Antarctica
复制标题
方丹冥王星：来自南极洲维多利亚地南部的早期罗斯造山运动钙碱性辉长岩
DOI：
--
复制
发表时间：
2006
期刊：
影响因子：
--
通讯作者：
A. Cooper
中科院分区：
文献类型：
--
作者：
J. Cottle;A. Cooper
方丹岩体是出露于南极洲维多利亚地南部卡里昂冰川南侧方丹海崖的一个未曾描述过的镁铁质侵入体。它是罗斯造山运动初始阶段侵位于中地壳深度的横向广泛镁铁质岩套的最南部成员。该岩体由再结晶角闪石-黑云母辉长岩组成，在某些地方显示出清晰的厘米至米级原生火成岩分层。推测由角闪石-滑石-滑石组成的复盖超镁铁质包体是化学和矿物学上不同的堆晶部分的残余。该岩体的87 Sr/86 Sr（i）比值为0.70679，143 Nd/144 Nd（i）比值为0.51187（Nd（i）=-1.2）。结合其他地球化学资料，这表明方丹岩体是由c. 15%的部分熔融耗尽地幔源，随后被大陆地壳污染。锆石U-Pb年代学初步结果显示岩体侵位年龄为546 ±10 Ma。这些新的数据表明，罗斯造山岩浆活动在这一地区的南部维多利亚土地开始在新元古代晚期沿着俯冲板块边缘。
Abstract The Fontaine Pluton is a previously undescribed mafic intrusion outcropping at Fontaine Bluff on the south side of the Carlyon Glacier in southern Victoria Land, Antarctica. It is the southern‐most member of a laterally extensive mafic suite emplaced at mid‐crustal depths during the initial stages of the Ross Orogeny. The pluton comprises recrystal‐lised hornblende‐biotite gabbro, which in places shows well‐defined centimetre to metre scale primary igneous layering. Recrystallised ultramafic enclaves composed of amphibole‐chlorite‐talc are inferred to be remnants of a chemically and mineralogically distinct cumulate fraction. The intrusion has a 87Sr/86Sr(i) ratio of 0.70679 and a 143Nd/144Nd(i) ratio of 0.51187 (ϵNd(i) = ‐1.2). This, coupled with other geochemical data, implies that the Fontaine Pluton was formed by c. 15% partial melting of a depleted mantle source that was subsequently contaminated by continental crust. Preliminary U‐Pb geochronology on zircon suggests an emplacement age for the pluton of 546 ±10 Ma. These new data indicate that Ross Orogeny magmatism in this area of southern Victoria Land was initiated in the late Neoproterozoic along a subducting plate margin.