Abstract We defined the folding sequence of the fold–thrust belt of the Western Papua New Guinea Highlands by analysing the surface expression of the structures and the response of the drainage system to the active fold–thrust belt. The interaction between structures is typically assessed by examining the syn-kinematic strata preserved; however, in our study area, this is problematic as these strata are poorly imaged on seismic lines. This study found common morphological features that allowed grouping and mapping of three different structural settings: group I, basement-involved tectonics; group II, thin-skinned anticlines which sole near the Koi–Iangi Sandstone; and group III, thin-skinned folds associated with the intra-Ieru Formation detachment. Fold Front Sinuosity analysis supports the idea that the fold–thrust belt propagates from the NW to the SE. Considering the detailed morphotectonics and drainage analyses, we interpret that the group II folds developed as out-of-sequence thrusting and folding, associated with buttressing against the group I larger structures.

Abstract: Using a script that automatically calculates sinuosity and radius of curvature for multiple bends on sinuous channel centerlines, we have assembled a new data set that allows us to reevaluate the relationship between latitude and submarine channel sinuosity. Sinuosity measurements on hundreds of channel bends from nine modern systems suggest that there is no statistically significant relationship between latitudinal position and channel sinuosity. In addition, for the vast majority of submarine channels on Earth, using flow velocities that are needed to transport the coarse-grained sediment found in channel thalwegs, estimates of the curvature-based Rossby number are significantly larger than unity. In contrast, low flow velocities that characterize the upper parts of turbidity currents in submarine channels located at high latitudes can easily result in Rossby numbers of less than one; this is the reason why levee deposits are often highly asymmetric in such channels. However, even in channels with asymmetric levees, the sinuosity of the thalweg is often obvious and must have developed as the result of an instability driven by the centrifugal force. Analysis of a simple centerline-evolution model shows that the increase in channel curvature precedes the increase in sinuosity and that low sinuosities are already associated with large curvatures. This suggests that the Coriolis effect is unlikely to be responsible for the low sinuosities observed in certain systems.