关键词: 朵叶体, 水道化, 沉积构型, 发育演化, 深水区, 坎波斯盆地

Abstract: As the major components of submarine fan systems, submarine channels and lobes receive much attention from the sedimentological community. However, studies about the“channel-lobe transitional zone”and the associated channelized lobes are still not enough. This study takes the Block ABL in deep-water areas of Campos Basin of Brazil as the example and recognizes different depositional elements of sandy channels, muddy channels, and sheet lobes, which suggests that channelized lobes are widely developed within the study area. We then characterize the overall deposition and internal architecture of channelized lobes, analyze the associated controlling factors, and establish the evolution model. The results suggest that the overall deposition of channelized lobes show significant variations between different locations; compared with the deposition in southern and downdip area, lobes in northern and proximal areas are more channelized. About the internal architecture, the channelized lobes could be divided into 3 lobe elements, which developed from north to south in terms of sequence. Lobe element 1 was mainly controlled by the source from north, which developed lots of distributaries and was more channelized. Controlled by the main source, Lobe element 2 was oriented along the major feeder channel; due to the gradual decreasing of topographic gradient, the degree of channelization of Lobe element 2 decreased. Lobe element 3 was mainly controlled by the behavior of gravity flow in the major feeder channel; around the bend of major feeder channel, gravity flows were stripped and deposited rapidly, which caused the formation of Lobe element 3 with relatively weak degree of channelization.

Key words: lobe, channelization, depositional architecture, development model, deep-water area, Campos Basin