Gravimetric survey and modeling of the basement morphology in the sedimentary thickness characterization, NE portion of Paraná Sedimentary Basin - Brazil

ABSTRACT: The northeast portion of the Paraná Sedimentary Basin is distinguished by structural highs as the known Pitanga Dome, an uplifted structure identified in the last century. It represents a geological and evolutionary evidence of the Paraná Sedimentary Basin and has undergone inspired studies and intense exploration surveys. This study consists of a gravimetric survey in the Pitanga Dome area, State of São Paulo, Brazil. The Bouguer gravity anomalies have been identified and related to the structural high, sedimentary thickness, and the basement morphology. Processing and enhancement techniques were used for forward modeling based on previous studies. The three models from profiles sectioning the dome have a sedimentary thickness varying from 200 to 1.250 meters. The adopted methodology has provided important results determining that the Pitanga Dome can be understood through rational 3D visualization. The area can be interpreted as an undulating basement with thinning of sedimentary rocks related to deep features (structures) in the crust/mantle limit (Moho uplift). This characteristic is confirmed by the sedimentary layer thickening present throughout the surrounding area. The results also offer important insights and support for further studies concerning the genesis and evolution of this and other uplifted structures of the Paraná Sedimentary Basin.

摘要：巴拉那沉积盆地（Paraná Sedimentary Basin）东北部以构造隆起为典型特征，其中以皮唐加穹窿（Pitanga Dome）最为知名——该抬升构造于上个世纪被发现。该构造是巴拉那沉积盆地地质与演化过程的重要实证，已开展诸多富有启发性的研究与高强度勘探调查。本研究针对巴西圣保罗州皮唐加穹窿区域开展重力测量工作，识别出布格重力异常（Bouguer gravity anomalies），并将其与构造隆起、沉积厚度及基底形貌相关联。研究基于前期成果，通过数据处理与增强技术开展正演模拟。三条横穿该穹窿的剖面所构建的模型显示，其沉积厚度介于200米至1250米之间。本研究所采用的方法取得了重要成果，证实可通过合理的三维可视化手段解析皮唐加穹窿的构造特征。该区域可被解译为起伏状基底，其沉积岩层的减薄现象与壳幔边界（莫霍面抬升，Moho uplift）处的深部构造特征相关；周边区域普遍存在的沉积层增厚现象，进一步验证了这一特征。本研究结果还为探究巴拉那沉积盆地内该穹窿及其他抬升构造的成因与演化提供了重要参考与支撑。