Subsidence in the Midst of Plateau Uplift: Neogene Evaporitic Basins of Northwest Argentina

人们对形成于岩浆弧和高原内的沉积盆地知之甚少。基本问题包括：是否有任何构造下沉或只是沉积物的堆积？这种构造下沉是由于岩浆运动、地壳变薄、逆冲加载还是重新激活先前存在的密度异常？尽管在其他背景下对沉积盆地的成因进行了广泛的研究，但对此类盆地的观察和理论处理很少。约旦将研究阿根廷西北部普纳高原中央安第斯山脉的新近纪和第四纪弧内/高原内盆地。晚中新世至现代沉积中心，在整个地区隆升的同时，积累了2000-5000米的地层。盆地成因的潜在线索包括它们与重力高点的巧合，以及它们缺乏沉积物的事实。蒸发岩相具有重要的体积、寿命和重要的经济意义。这项工作将记录盆地从中新世到最近的古地理。对岩相、盆地填充物与邻近基岩的接触关系、物源和古水流的研究将得到夹层灰烬的绝对年代测定的补充。

Sedimentary basins that form within magmatic arcs and plateaus are poorly understood. Basic questions include: Has there been any tectonic subsidence or just ponding of sediment? Is such tectonic subsidence due to magmatic movement, crustal thinning, thrust loading, or reactivation of pre-existing density anomalies? Observations and theoretical treatments of such basins are rare, in spite of extensive study of the genesis of sedimentary basins in other settings. Jordan will study Neogene and Quaternary intra- arc/intraplateau basins of the Central Andes mountain chain, in the Puna plateau of northwestern Argentina. Late Miocene to Recent depocenters accumulated 2000 to 5000 m of strata while the whole region was being uplifted. Potential clues to the causes of the basins include their coincidence with gravity highs and the fact that they are sediment-starved. Evaporite facies are volumetrically important, long-lived, and economically important. The work will document the paleogeography of the basins through the Miocene to Recent. Study of facies, contact relations between the basin fill and adjacent bedrock, provenance and paleocurrents will be complemented by absolute dating of intercalated ashes.