Rb–Sr geochronology of metamorphic rocks from the Central Indonesian Accretionary Collision Complex: Additional age constraints for the Meratus and Luk Ulo complexes (South Kalimantan and Central Java)
Rb–Sr geochronology of metamorphic rocks from the Central Indonesian Accretionary Collision Complex: Additional age constraints for the Meratus and Luk Ulo complexes (South Kalimantan and Central Java)
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印度尼西亚中部增生碰撞杂岩变质岩的 RbâSr 地质年代学：Meratus 和 Luk Ulo 杂岩（南加里曼丹和中爪哇）的附加年龄限制
DOI：
10.1016/j.lithos.2021.105971
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发表时间：
2021
期刊：
影响因子：
3.5
通讯作者：
Setiawan NI
中科院分区：
文献类型：
--
作者：
Alfing J;Bröcker M;Setiawan NI
印度尼西亚中部增生碰撞杂岩的变质岩在爪哇岛、苏拉威西岛和加里曼丹岛广泛分布。它们与一个或多个俯冲带的关系是有争议的，这可以部分解释为地质年代学研究不足。利用铷-锶年代学，我们已经从Meratus复杂，南加里曼丹，和卢克乌罗复杂，中爪哇的各种片岩。Meratus片岩首先经历了高压/低温（HP/LT）变质作用，后来在中压条件下叠加。由于这类岩石的稀有性和保存性差，目前尚不能确定保存完好的高压/低温岩石的同位素年龄。先前获得的K-Ar白色云母年龄（180-160 Ma）归因于HP/LT事件，然而，这是推测性的，因为测年岩石仅记录绿片岩-角闪岩相P-T条件。一个新测年的部分叠印但仍富含蓝闪石的样品获得了定义明确的Rb-Sr等时线年龄（多硅白云母、绿帘石）112.9 ± 0.7 Ma（Rb-Sr测年的所有不确定性均表示95%置信水平），为HP/LT阶段提供了最小年龄。内部矿物等时线的更严重的叠印样品显示云母和相关阶段之间的线性拟合差，表明不完全重置的Rb-Sr同位素系统在较低的压力变质事件。仅从白色云母的不同粒度组分中获得的等时线表明其年龄在115 ~ 110 Ma（± 3 ~ 6 Ma）之间。与以前的解释，高品位的岩石的Meratus复杂的碰撞引起的地壳增厚，它在这里被认为更有可能，这些岩石要么代表异国情调的片段从澳大利亚西北部或变质唯一的Meratus蛇绿岩。从卢克Ulo复杂的HP/LT岩石的温度估计的差异可能表明平衡矿物组合和/或成分的错误的纹理解释。无论是岩石学分析还是地质年代学测年，都没有明确地证实卢克乌洛地区榴辉岩的不同P-T-tpaths（含和不含电气石）。新测年的含Trm绿帘石蓝片岩来自蛇纹质芒卡尔河混杂岩，其Rb-Sr等时线为119.0 ± 0.7 Ma（多硅白云母、绿帘石、电气石），与不含Trm的HP/LT岩石的现有K-Ar和Rb-Sr数据完全匹配。Luk Ulo地区分布较广的石榴石-多硅白云母片岩的两个样品获得了118.0 ± 0.8 Ma和114.7 ± 1.3 Ma的Rb-Sr年龄（多硅白云母，长石）。在这些碎屑变质沉积岩中含有一个米级绿帘石角闪岩块体，其Rb-Sr等时线年龄为116.8 ± 0.7Ma（多硅白云母、绿帘石、全岩）。这些年龄匹配现有的K-Ar数据严重叠印岩石从卢克乌罗地区，并进一步证实了早白垩世变质作用在中爪哇的地质意义。Meratus和Luk Ulo杂岩的岩石学和地质年代学数据符合一个模型，表明这两个产状属于同一个白垩纪俯冲系统。另一个白垩纪的缝合带可能穿过苏拉威西岛。
Metamorphic rocks of the Central Indonesian Accretionary Collision Complex are exposed in widely scattered occurrences on the islands of Java, Sulawesi, and Kalimantan. Their relationship to one or more subduction zones is controversial which can partly be explained by insufficient geochronological investigation. Using Rb–Sr geochronology we have dated various schists from the Meratus Complex, South Kalimantan, and the Luk Ulo Complex, Central Java. The Meratus schists first experienced high-pressure/low-temperature (HP/LT) metamorphism and were later overprinted at medium pressure conditions. Due to the rarity and poor preservation of such rocks, isotopic ages for well-preserved HP/LT rocks could not be determined yet. Previously obtained K–Ar white mica dates (180–160 Ma) were attributed to the HP/LT event, however, this was speculative as the dated rocks only record greenschist- to amphibolite-faciesP–Tconditions. A newly dated partially overprinted but still glaucophane-rich sample yielded a well-defined Rb–Sr isochron age (phengite, epidote) of 112.9 ± 0.7 Ma (all uncertainties on Rb–Sr dates indicate 95% confidence level), providing a minimum age for the HP/LT stage. Internal mineral isochrons of more severely overprinted samples show poor linear fits between mica and associated phases indicating incomplete resetting of the Rb–Sr isotope system during the later lower pressure metamorphic event. Isochrons that are derived only from different grain-size fractions of white mica indicate dates between 115 and 110 Ma (± 3 to 6 Ma). In contrast to previous interpretations that linked high-grade rocks of the Meratus Complex to collision-induced crustal thickening it is here considered more likely that these rocks either represent exotic fragments from NW Australia or the metamorphic sole of the Meratus ophiolite. Differences in temperature estimates for HP/LT rocks from the Luk Ulo Complex probably indicate erroneous textural interpretation of equilibrium mineral assemblages and/or compositions. Neither petrological analysis nor geochronological dating has yet unambiguously confirmed differentP–T–tpaths for eclogites with and without tourmaline (Trm) from the Luk Ulo area. The newly dated Trm-bearing epidote blueschist from the serpentinitic Muncar River mélange yielded a well-defined Rb–Sr isochron of 119.0 ± 0.7 Ma (phengite, epidote, tourmaline) that perfectly matches with existing K–Ar and Rb–Sr data for Trm-free HP/LT rocks. Two samples of the more widespread garnet-phengite schists of the Luk Ulo area yielded Rb–Sr ages (phengite, feldspar) of 118.0 ± 0.8 Ma and 114.7 ± 1.3 Ma. A meter-sized epidote amphibolite block included in these clastic metasedimentary rocks provided a Rb–Sr isochron age of 116.8 ± 0.7 Ma (phengite, epidote, whole rock). These ages match existing K–Ar data for severely overprinted rocks from the Luk Ulo area and further corroborate the geological significance of Early Cretaceous metamorphism in Central Java. Petrological and geochronological data of the Meratus and Luk Ulo complexes are in accordance with a model suggesting that both occurrences belong to the same Cretaceous subduction system. The existence of an additional Cretaceous suture zone cutting through Sulawesi is considered likely.
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影响因子：
1.5
作者：
K. Wakita;Munasri;J. Sopaheluwakan;I. Zulkarnain;Kazuhiro Mlyazaki
通讯作者：
K. Wakita;Munasri;J. Sopaheluwakan;I. Zulkarnain;Kazuhiro Mlyazaki
影响因子：
5
作者：
Villa, I. M.;De Bievre, P.;Renne, P. R.
通讯作者：
Renne, P. R.
影响因子：
3.5
作者：
Mischa Böhnke;M. Bröcker;A. Maulana;R. Klemd;J. Berndt;H. Baier
通讯作者：
Mischa Böhnke;M. Bröcker;A. Maulana;R. Klemd;J. Berndt;H. Baier
印度尼西亚苏拉威西岛南臂基岩的 LA-ICP-MS 锆石 U-Pb 和白云母 K-Ar 年龄
影响因子：
3.5
作者：
A. Jaya;O. Nishikawa;Y. Hayasaka
通讯作者：
Y. Hayasaka
DOI：
10.1144/gsl.sp.1996.106.01.23
发表时间：
1996
期刊：
Geological Society, London, Special Publications
影响因子：
--
作者：
K. Wakita;J. Sopaheluwakan;K. Miyazaki;I. Zulkarnain;Munasri
通讯作者：
K. Wakita;J. Sopaheluwakan;K. Miyazaki;I. Zulkarnain;Munasri