汤原断陷古近系扇三角洲沉积特征

汤原断陷新安村组-达连河组中广泛发育扇三角洲沉积。根据岩心观察、测井和地震资料分析、岩性鉴定、粒度分析等资料，识别出扇三角洲平原、扇三角洲前缘、前扇三角洲3个亚相，并进一步识别出8个微相。从扇三角洲平原到扇三角洲前缘，不同沉积微相的沉积特征呈现规律性的变化：沉积物结构如支撑关系由杂基支撑到颗粒支撑，颗粒间由点接触变为面接触，颗粒分选由差到好，成熟度由低到高，沉积物的粒度由粗变细等；沉积层理构造由扇三角洲平原砂砾混杂的块状层理到前缘小型低角度的交错层理、波状层理等；概率累计曲线由扇三角洲平原的一段式、低角度两段式到扇三角洲前缘的斜率较大的二段式、三段式；在C-M图上，扇三角洲平原的点群多在C、M值较大的PQ段，前缘多在OR、RS段。在此基础上，结合岩心特征、粒度分析等资料得出扇三角洲的水动力机制主要为牵引流沉积，少量重力流沉积。

Sedimentary Characters of Fan Delta of Paleocene in Tangyuan Fault Depression

Fan deltas are widely developed in Xin'ancun and Dalianhe Formation of Tangyuan fault depression.According to core observation,well logging,seismic,lithology identification and grain size analysis,three subfacies including fan-delta plain,fan-delta front and pro-fan delta and eight microfacies are identified.From fan-delta plain to fan-delta front,the sedimentary characteristics of different microfacies changes regularly.The sediment textures such as the supporting type change from matrix-support to grain-s...