Data for: PROVENANCE OF CRETACEOUS SANDSTONES IN THE BANDA ARC AND THEIR TECTONIC SIGNIFICANCE

The provenance of Cretaceous sandstones in the Banda Arc islands differs from west to east. Sandstones in Sumba and West Timor contain significant amounts of feldspar (K-feldspar and plagioclase) and lithic fragments, suggesting a recycled to magmatic arc origin. In comparison, East Timor and Tanimbar sandstones are quartz rich, and suggest a recycled origin and/or continental affinity. Heavy mineral assemblages in Sumba and West Timor indicate metamorphic and minor acidic igneous sources and include a mixture of rounded and angular zircon and tourmaline grains. In East Timor, Babar and Tanimbar, an ultimate origin from a mainly acid igneous and minor metamorphic source is interpreted, containing a mixture of rounded and angular zircon and tourmaline grains. Detrital zircon ages in all sandstones range from Archean to Mesozoic, but variations in age populations indicate local differences in source areas. Sumba and West Timor are characterised by zircon age peaks at 80-100 Ma, 200-240 Ma, 550 Ma, 1.2 Ga, 1.5 Ga and 1.8 Ma. East Timor and Tanimbar contain 80-100 Ma, 160-200 Ma, 240-280 Ma, 550 Ma and 1.5 Ga zircon peaks. Most populations are also common in Triassic and Jurassic formations along the Outer Banda Arc and in many other areas of SE Asia. However, the abundance of Jurassic and Cretaceous populations was unexpected. We interpret Cretaceous sandstones from Sumba, Timor and Tanimbar to have been deposited in SE Sundaland. Syn-sedimentary Cretaceous (68-140 Ma) sources are suggested to include the Schwaner Mountains in SW Borneo and Sumba. Material derived mainly from older recycled sediments that had their main sources in the Bird’s Head, Western and Central Australia, and local sources close to Timor.

班达弧群岛的白垩纪砂岩物源呈现东西向分异特征。松巴岛与帝汶西部的砂岩富含长石（钾长石与斜长石）及岩屑，指示其物源兼具再旋回与岩浆弧成因属性。与之相较，帝汶东部与塔宁巴尔群岛的砂岩以富石英为典型特征，暗示其物源为再旋回沉积物或具有大陆亲缘性。松巴岛与帝汶西部的重矿物组合指示变质物源与少量酸性火成物源，其中混合产出磨圆状与棱角状的锆石、电气石颗粒。在帝汶东部、巴伯尔岛与塔宁巴尔群岛，研究认为其最终物源主要来自酸性火成岩，辅以少量变质岩源区，同样存在磨圆状与棱角状锆石、电气石的混合颗粒。所有砂岩的碎屑锆石年龄跨度均为太古代至中生代，但年龄谱系的差异反映了物源区的区域分异。松巴岛与帝汶西部的锆石年龄峰值集中于80~100 Ma、200~240 Ma、550 Ma、1.2 Ga、1.5 Ga及1.8 Ma；帝汶东部与塔宁巴尔群岛的锆石年龄峰值则为80~100 Ma、160~200 Ma、240~280 Ma、550 Ma及1.5 Ga。上述多数年龄谱系在班达弧外缘的三叠纪、侏罗纪地层以及东南亚诸多其他区域均有分布，但侏罗纪与白垩纪年龄谱系的丰度却超出预期。我们认为，松巴岛、帝汶与塔宁巴尔群岛的白垩纪砂岩沉积于巽他陆块东南部。其同期沉积的白垩纪（68~140 Ma）物源可能包括婆罗洲西南部的斯瓦讷山脉与松巴岛；此外，部分物质主要来自再旋回的古老沉积物，其主要物源区为鸟头半岛、西澳大利亚与中澳大利亚，以及邻近帝汶的局地物源。