Sedimentary provenance of Mid-Devonian clastic sediments in the Teplá-Barrandian Unit (Bohemian Massif): U–Pb and Pb–Pb geochronology of detrital zircons by laser ablation ICP-MS
Sedimentary provenance of Mid-Devonian clastic sediments in the Teplá-Barrandian Unit (Bohemian Massif): U–Pb and Pb–Pb geochronology of detrital zircons by laser ablation ICP-MS
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Teplá-Barrandian 单元（波希米亚地块）中泥盆世碎屑沉积物的沉积物源：通过激光烧蚀 ICP-MS 进行碎屑锆石 U-Pb 和 Pb-Pb 地质年代学
DOI：
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发表时间：
2005
期刊：
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通讯作者：
M. Mihaljevič
中科院分区：
文献类型：
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作者：
L. Strnad;M. Mihaljevič
摘要通过激光烧蚀ICP-MS U-Pb锆石测年、大块沉积物地球化学和重矿物组分矿物学研究，研究了波希米亚地块Teplá-Barrandian单元中泥盆统碎屑沉积物的物源。与TBU新元古代沉积物的岛弧物源相反，早古生代沉积物中含有大量分异的地壳物质。Barrandian中泥盆统粉砂岩和砂岩的碎屑锆石种群年龄从太古代（~ 3.0 Ga）到早古生代（~ 0.39 Ga）不等。最大年龄为~ 2.6 Ga、2.0 ~ 2.25 Ga、0.62 Ga和0.51 Ga。迄今发现的最年轻的锆石对应于下泥盆世和中泥盆世。从太古宙（3.0、2.8和2.6 Ga）到古元古代（2.25-2.0 Ga）的锆石广泛的机械磨损表明它们的物源来自于循环的古沉积层序。年龄在~ 2.0 ~ 3.0 Ga之间的锆石数量较多，可能表明中泥盆统沉积物源区存在太古宙/古元古代地壳遗迹。碎屑锆石年龄在~ 0.9 ~ 1.2 Ga之间的缺失和锆石年龄在~ 2.0 ~ 2.25 Ga和0.5 ~ 0.8 Ga之间的存在，对应于与冈瓦纳有关的北非，而不是与冈瓦纳有关的南美和波罗的海地体的锆石年龄模式。该物质主要从西部进入盆地，主要由寒武纪花岗岩类碎屑物质和新元古代变质沉积层序的再循环物质组成。
SummaryThe provenance of the Mid-Devonian clastic sediments in the Teplá-Barrandian Unit (TBU) of the Bohemian Massif was investigated by laser ablation ICP-MS U–Pb zircon dating, bulk sediment geochemistry and mineralogical study of the heavy mineral fraction. In contrast to the island arc provenance of the TBU Neoproterozoic sediments, the Early Palaeozoic sediments contain significant amounts of differentiated crustal material. The detrital zircon populations in the Barrandian Mid-Devonian siltstones and sandstones show ages ranging from Archaean (∼3.0 Ga) to Early Palaeozoic (∼0.39 Ga). Major age maxima are at ∼2.6 Ga, 2.0–2.25 Ga, 0.62 and 0.51 Ga. The youngest identified zircons so far correspond to Lower and Mid-Devonian ages. The extensive mechanical abrasion of zircons having Archaean (3.0, 2.8 and 2.6 Ga) to Paleoproterozoic ages (2.25–2.0 Ga) suggest their provenance from recycled old sedimentary sequences. The relatively large number of zircons with ages between ∼2.0 and 3.0 Ga may indicate the presence of relicts of the Archaean/Paleoproterozoic crust in the source areas of the studied Mid-Devonian sediments. The absence of detrital zircon ages between ∼0.9 and 1.2 Ga and the presence of zircon ages of ∼2.0–2.25 and 0.5–0.8 Ga correspond to the zircon age pattern from the Gondwana-related North African, rather than Gondwana-related South American and Baltic terranes. The material was entering the basin predominantly from the west and consisted primarily of detrital material of Cambrian granitoids and recycled material of Neoproterozoic meta-sedimentary sequences.