Abstract The Arabian-Nubian Shield (ANS) is a province of mostly juvenile Neoproterozoic continental crust in NE Africa and Arabia, forming the northern extension of the East-African orogen. Subsequent to widespread, mostly late- to post-orogenic early-Ediacaran calc-alkaline granitoid emplacement, the latest magmatic phase in the ANS saw the intrusion of alkaline shallow plutons alongside volcanic massifs and dikes of variable compositions. While some of these intrusions were dated to 550–530 Ma by Rb-Sr and Ar-Ar, U-Pb zircon data has mostly limited ANS magmatism to no younger than ca. 580 Ma. Here we report new age and isotopic data from latest Neoproterozoic intrusions along a N-S transect within the northern ANS and its periphery, substantiating the record of a ca. 550 Ma igneous-thermal event in the area. In the northern Negev of Israel, mafic igneous rocks intruded into the subsurface late Neoproterozoic clastic wedge of the Zenifim Formation produced apatite U-Pb isochron ages between 557 and 545 Ma. In the Amram alkaline massif, 150 km to the south, an alkali-granite was dated to 605 ± 2.5 Ma by zircon U-Pb, but apatite U-Pb ages from all rocks of the massif concentrate at ca. 550 Ma indicating thermal resetting. Apatites from the zircon dated 611 ± 5 Ma Roded quartz diorite in the Elat area, south of Amram, produced a 600 ± 4 Ma U-Pb age, demonstrating that southern segments were not thermally reset at ca. 550 Ma. Nd isotopes in apatite and whole rock show the ca. 550 Ma igneous rocks to be variable in their isotopic composition, ranging between eNd(t)=(-4) – (+2), far less juvenile than typical ANS magmas. The ca. 550 Ma intrusions resemble in their age and isotopic properties Cadomian granites and volcanic rocks that are known from southern Turkey, Iran and Europe. We interpret the ca. 550 Ma igneous overprint and thermal resetting documented in the northernmost ANS as related to the superposition of Cadomian orogeny on the ANS periphery. This can be related to the late Ediacaran subduction of proto-Tethys accompanying the accretion of the Cadomian basement of the Tauride block to NE Africa and Arabia, before the area was overstepped by Cambrian platform sedimentation.

中文翻译：

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北阿拉伯-努比亚地盾（以色列南部和中部）上的 Cadomian（约 550 Ma）岩浆和热印记：新时代和同位素约束

摘要 阿拉伯-努比亚地盾（ANS）是位于非洲东北部和阿拉伯的一个以新生的新元古代大陆地壳为主的省份，形成了东非造山带的北部延伸。在广泛的、主要是晚期至造山后早期埃迪卡拉纪钙碱性花岗岩侵位之后，ANS 中最新的岩浆期看到碱性浅岩体侵入火山地块和成分可变的岩脉。虽然其中一些侵入体被 Rb-Sr 和 Ar-Ar 确定为 550-530 Ma，但 U-Pb 锆石数据主要将 ANS 岩浆活动限制在不小于约 550 年。580 马。在这里，我们报告了来自 ANS 北部及其外围沿 NS 横断面的最新新元古代侵入体的新时代和同位素数据，证实了约 该地区发生 550 Ma 火成热事件。在以色列北部的内盖夫，侵入到 Zenifim 组地下晚新元古代碎屑楔的镁铁质火成岩产生了磷灰石 U-Pb 等时线年龄在 557 至 545 Ma 之间。在南部 150 公里的阿姆拉姆碱性地块中，锆石 U-Pb 确定碱性花岗岩的年龄为 605 ± 2.5 Ma，但地块所有岩石中的磷灰石 U-Pb 年龄约为 550 Ma 指示热复位。来自阿姆拉姆以南 Elat 地区的锆石磷灰石的年龄为 611 ± 5 Ma 棒状石英闪长岩，产生了 600 ± 4 Ma U-Pb 年龄，表明南段在约 550 马。磷灰石和整块岩石中的 Nd 同位素显示约。550 岩浆岩的同位素组成各不相同，范围在 eNd(t)=(-4) – (+2) 之间，远不如典型的 ANS 岩浆年轻。约。550 Ma 侵入体的年龄和同位素性质与土耳其南部、伊朗和欧洲已知的 Cadomian 花岗岩和火山岩相似。我们解释约。记录在 ANS 最北端的 550 次火成岩叠印和热复位与 Cadomian 造山作用在 ANS 外围的叠加有关。这可能与 Ediacaran 晚期原始特提斯的俯冲有关，伴随着 Tauride 地块的 Cadomian 基底向非洲东北部和阿拉伯的增生，在该地区被寒武纪台地沉积超越之前。