New insights into the accretion of the Arabian-Nubian Shield: Depositional setting, composition and geochronology of a Mid-Cryogenian arc succession (North Eastern Desert, Egypt)
New insights into the accretion of the Arabian-Nubian Shield: Depositional setting, composition and geochronology of a Mid-Cryogenian arc succession (North Eastern Desert, Egypt)
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对阿拉伯-努比亚地盾增生的新见解：中成冰世弧序列的沉积环境、成分和地质年代学（埃及东北沙漠）
DOI：
10.1016/j.precamres.2013.12.012
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发表时间：
2014
影响因子：
3.8
通讯作者：
Linnemann
中科院分区：
文献类型：
--
作者：
Bühler;Breitkreuz;Pfänder;Hofmann;Becker;Linnemann
北部阿拉伯-努比亚盾(ANS)的增长阶段受到的限制很小。首次将相分析、地球化学、LA-ICPMS锆石U-Pb年代学与黑云母、角闪石40Ar/39Ar年代学相结合，对东北沙漠中低温世火山-沉积序列进行了研究。厚约550米的Wadi Malaak序列(WMS)不整合地覆盖在约750 Ma的花岗岩类上，并被约617 Ma的Ma Dokhan火山和Hammaat群沉积覆盖在一个角度不整合上。WMS的相演化由接受中远端长英质褐沸石岩席的冲积平原转变为具有镁铁质岩浆活动的湖相体系，然后又发育回具有双峰式火山作用的陆上环境。相分析表明，古气候条件湿润；没有检测到(冰缘)冰川特征。WMS样品的勘查地球化学表明，火山岩和火山碎屑岩的成分范围从玄武岩到流纹岩，具有钙碱性亲和力。不相容的微量元素和稀土配分模式表明形成于俯冲环境。选定的构造分类图显示为大陆弧背景。从两个长英质原生辉石中提取的锆石进行了U-PbLA-ICPMS分析，其年龄分别为725 Ma±10.7 Ma和717℃±9.8 Ma，将WMS的形成限制在中寒武世。角闪石和黑云母分离自明显侵入WMS的次火山辉长岩，其40Ar/39Ar冷却年龄分别为747 Ma±10.10 Ma和743 Ma±10.10 Ma。因此，40Ar/39Ar年龄与U-Pb结晶年龄相冲突。这是由于黑云母和角闪石中存在过量的Ar。新的资料表明，WMS是在斯特尔斯蒂安冰川开始之前的中寒武世隆升的衰退期形成的。这是已知的最北端约720 Ma弧形火山活动的第一个记录。
The accretionary phase of the northern Arabian-Nubian Shield (ANS) is poorly constrained. For the first time, this study combines facies analysis, geochemistry, LA-ICP-MS U–Pb zircon geochronology and biotite and hornblende40Ar/39Ar geochronology on a Mid-Cryogenian volcano-sedimentary succession situated in the North Eastern Desert (NED). The c. 550 m thick Wadi Malaak succession (WMS) nonconformably overlies c. 750 Ma granitoids and is, in turn, overlain by c. 617 Ma Dokhan Volcanics and Hammamat Group sediments on an angular unconformity. Facies evolution of the WMS switched from an alluvial plain receiving medial to distal felsic ignimbrite sheets to a lacustrine system with mafic phreatomagmatic activity, and then developed back to a subaerial environment with bimodal volcanism. Facies analysis suggests humid paleoclimatic conditions; (peri-)glacial features have not been detected. Reconnaissance geochemistry of WMS samples indicates a compositional range of volcanic and volcaniclastic rocks from basalt to rhyolite with calc-alkaline affinities. Incompatible trace element and REE patterns indicate formation in a subduction setting. Selected tectonic classification diagrams suggest a continental arc setting. U–Pb LA-ICP-MS analyses on zircon extracted from two felsic ignimbrites resulted in ages of 725 ± 7 Ma and 717 ± 8 Ma, constraining formation of the WMS to the Mid-Cryogenian. Hornblende and biotite separated from a subvolcanic gabbro that obviously had intruded the WMS yielded40Ar/39Ar cooling ages of 747 ± 10 Ma and 743 ± 10 Ma, respectively. These40Ar/39Ar ages are thus in conflict with the U–Pb crystallization ages. This is explained by the presence of excess Ar in biotite and hornblende. The new data presented here indicate that the WMS developed during the waning phase of Mid-Cryogenian ANS accretion, prior to the onset of Sturtian glaciation. It is the first known record of c. 720 Ma arc volcanism in the northernmost ANS.
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埃及西奈半岛约 844 Ma Moneiga 石英闪长岩：阿拉伯-努比亚地盾中安第斯型弧或裂谷相关岩浆作用的证据？
DOI：
--
发表时间：
2009
期刊：
影响因子：
--
作者：
F. Bea;M. Abu;P. Montero;P. Peres;C. Talavera
通讯作者：
C. Talavera
影响因子：
3.1
作者：
Whitney, Donna L.;Evans, Bernard W.
通讯作者：
Evans, Bernard W.
影响因子：
3.4
作者：
T. Jeffries;J. Fernández-Suárez;F. Corfu;G. G. Alonso-G.
通讯作者：
T. Jeffries;J. Fernández-Suárez;F. Corfu;G. G. Alonso-G.
DOI：
10.1007/978-3-642-80087-0_20
发表时间：
1996
期刊：
--
影响因子：
--
作者：
R. Blong
通讯作者：
R. Blong
火山渣锥和凝灰岩环
DOI：
--
发表时间：
2000
期刊：
影响因子：
--
作者：
Dirk Vespermann;H. Schmincke
通讯作者：
H. Schmincke