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Early Cretaceous subduction in NW Kalimantan: Geochronological and geochemical constraints from the Raya and Mensibau igneous rocks
Gondwana Research ( IF 6.1 ) Pub Date : 2021-08-30 , DOI: 10.1016/j.gr.2021.08.006
Yuejun Wang 1, 2 , Sainan Wu 1 , Xin Qian 1, 2 , Peter A. Cawood 3 , Xianghong Lu 1 , Chengshi Gan 1 , Junaidi Bin Asis 4 , Peizhen Zhang 1, 2
Affiliation  

The Kuching zone in NW Kalimantan and Malaysia Sarawak might be the southerly-extending segment of the paleo-Pacific subduction that is developed along the Coastal South China and SE Vietnam, and separated the Sundaland “old-land” from the Cenozoic Sibu zone. However, establishing this link is hindered by the lack of data on the Mesozoic orogenic history in NW Kalimantan. This paper presents zircon U-Pb geochronological and Hf-O isotopic data as well as whole-rock elemental and Sr-Nd-Pb isotopic results for the Raya Volcanics and their equivalents, as well as the Mensibau batholith in NW Kalimantan. The Raya Volcanics and Mensibau granitoids formed at 130–144 Ma, synchronous with the Menunuk Volcanics, but significantly older than the Pakong-Serabang mafic rocks and Serian Volcanics (~77–98 Ma) in the Sarawak Kuching zone. The Raya Volcanics and their equivalents belong compositionally to tholeiitic to low-K calc-alkaline series, and exhibit “spiky” PM-normalized patterns with Nb/La = 0.16–0.32, (87Sr/86Sr)i = 0.70187–0.70671 and εNd(t) = +0.9 to +3.6. Their (206Pb/204Pb)i, (208Pb/204Pb)i and (207Pb/204Pb)i range from 18.49 to 18.83, 38.39 to 39.19 and 15.57 to 15.70, and zircon εHf(t)-δ18O values from +4.1 to +16.1, and 5.21‰ to 6.05‰, respectively. They are derived from mantle wedge modified by recycled sediments. The Mensibau batholith is dominated by I-type granodiorite and granite. They share similar elemental ratios and Sr-Nd-Pb-Hf-O isotopic compositions with the Raya Volcanics, and originated from wedge-derived juvenile mafic crust. The temporal-spatial and geochemical accordance for the Raya Volcanics and Mensibau batholith document the extensive development of the early Cretaceous igneous rocks in NW Kalimantan. The Kuching zone is a northeasterly-propagated Cretaceous accretionary system that developed in response to the subduction of the paleo-Pacific plate.



中文翻译:

NW Kalimantan 早白垩世俯冲:来自 Raya 和 Mensibau 火成岩的年代学和地球化学约束

位于加里曼丹西北部和马来西亚砂拉越的古晋带可能是沿华南沿海和越南东南部发育的古太平洋俯冲带向南延伸的部分,将巽他大陆“旧陆”与新生代诗巫带分隔开。然而,由于缺乏有关加里曼丹西北部中生代造山历史的数据,建立这种联系受到阻碍。本文介绍了 Raya 火山及其等价物以及 NW Kalimantan 的 Mensibau 基岩的锆石 U-Pb 年代学和 Hf-O 同位素数据以及全岩元素和 Sr-Nd-Pb 同位素结果。Raya 火山和 Mensibau 花岗岩形成于 130-144 Ma,与 Menunuk 火山同步,但比砂拉越古晋地区的 Pakong-Serabang 基性岩和西连火山 (~77-98 Ma) 早得多。87 Sr/ 86 Sr) i  = 0.70187–0.70671 和 ε Nd (t) = +0.9 到 +3.6。它们的(206 PB / 204 Pb)的,(208 PB / 204 Pb)的和(207 PB / 204 Pb)的的范围从18.49到18.83,38.39至39.19和15.57至15.70,和锆石ε的Hf(t)的-δ 18O 值分别为 +4.1 至 +16.1 和 5.21‰ 至 6.05‰。它们来自由回收沉积物修饰的地幔楔。Mensibau 地基以 I 型花岗闪长岩和花岗岩为主。它们与拉雅火山具有相似的元素比例和 Sr-Nd-Pb-Hf-O 同位素组成,并且起源于楔形衍生的幼年基性地壳。Raya 火山和 Mensibau 基岩的时空和地球化学一致性记录了加里曼丹西北部早白垩世火成岩的广泛发育。古晋带是一个向东北传播的白垩纪增生系统,是响应古太平洋板块俯冲而发展起来的。

更新日期:2021-09-10
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