Abstract LA-ICP-MS U–Pb dating of detrital zircons reveals two levels of accumulation of Proterozoic quartzites in the Kyrgyz North Tianshan. The quartzites of the Makbal Formation in the core of the Makbal anticlinorium have a maximum depositional age of 1.7 Ga and characterize the oldest stage of accumulation of quartzites in the western Central Asian Orogenic Belt. Quartzites of the Ovva Formation in the northeastern limb of the Makbal anticlinorium and Djeldysu Formation in the Burkhan anticlinorium have maximum depositional ages of ca. 1.0 Ga. Distributions of detrital zircon ages in these two formations are identical and indistinguishable from detrital zircon age distributions in the Neoproterozoic quartzites of the North Kazakhstan. The latter three quartzitic units have common provenance and, apparently, represent the same stratigraphic level. Distinctly different distributions of detrital zircon ages indicate that Precambrian microcontinents of the Kokchetav-North Tianshan zone represented independent continental massif with respect to Precambrian crustal blocks of the Middle Tianshan and Tarim Craton.

中文翻译：

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吉尔吉斯北天山古元古代和新元古代石英岩：根据碎屑锆石测年结果确定年龄

摘要 碎屑锆石的 LA-ICP-MS U-Pb 定年揭示了吉尔吉斯北天山元古界石英岩的两个层次积累。位于 Makbal 背斜区核心的 Makbal 组石英岩的最大沉积年龄为 1.7 Ga，是中亚造山带西部最古老的石英岩堆积阶段。Makbal 背斜区东北翼的 Ovva 组石英和 Burkhan 背斜区的 Djeldysu 组石英岩的最大沉积年龄约为 1.0 Ga。这两个地层中碎屑锆石年龄分布与北哈萨克斯坦新元古代石英岩中碎屑锆石年龄分布相同且难以区分。后三个石英岩单元具有共同的出处，显然，代表同一地层。碎屑锆石年龄分布的明显不同表明，相对于中天山和塔里木克拉通的前寒武纪地块，科克切塔夫-北天山带的前寒武纪微大陆代表了独立的大陆地块。