This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

It is now well-established that base-salt relief drives complex deformation in the mid-slope domain of salt-bearing passive margins, in a location classically thought to be dominated purely by horizontal translation. However, due to a lack of detailed studies drawing on high-quality, 3D seismic reflection data, our understanding of how base-salt relief controls four-dimensional patterns of salt-related deformation in natural systems remains poor. We here use 3D seismic reflection data from, and structural restorations of the Outer Kwanza Basin, offshore Angola to examine the controls on the evolution of variably oriented salt anticlines, rollers, and walls, and related normal and reverse faults. We show that the complex geometries and kinematics of predominantly contractional salt structures reflect up to 22 km of seaward flow of salt and its overburden across prominent base-salt relief. More specifically, contractional deformation occurs where seaward salt flow: (i) is retarded, and salt thickens and overburden buckles above landward-dipping ramps; (ii) encounters thick, slower-moving salt at the base of seaward-dipping ramp; (iii) translates across an array of concave-into-the-basin ramps; (iv) is retarded due to the formation of primary salt welds at the upper hinge of seaward-dipping ramps. The rate at which salt and its overburden translates seaward varies along strike due to corresponding variations in the magnitude of base-salt relief and, at a larger scale, primary salt thickness. As a result, overburden rotation accompanies bulk contraction. Our study improves our understanding of salt-related deformation on passive margins, highlighting the key role of base-salt relief, and showing contraction and rotation are fundamental processes in mid-slope translational domains of salt basins.

Click here and insert your abstract text. Physical properties of reservoir and seal-layer samples are essential information to evaluate the storage and seal potential and to predict long term CO 2 behaviour in reservoir. In this study, we measure the elastic wave velocities (V p and V s ), porosity and density of sandstone, limestone and lime-mudstone samples are measured of Ngrayong Fm. and Bulu Fm, Central Java, Indonesia. The sandstones indicate low V p , V s , density and high porosity. These results suggest that sandstones on Ngrayong Fm. have large porosity and became important candidate of CO 2 reservoir. On the other hand, limemudstone indicates high velocities with low porosity and point out that they have enough potential to be sealing layer of injected CO 2 .

We here use a 3D seismic reflection dataset from the Outer Kwanza Basin, offshore Angola to examine the structure and growth of salt‐detached strike‐slip faults. The faults occur in four, up to 13.8 km‐long, NE‐trending arrays that are physically linked by restraining bends and releasing stepovers, and which presently overlie Aptian salt and base‐salt relief related to pre‐salt faulting. We suggest that these faults formed to accommodate along‐margin variations in the rate and magnitude of differential seaward translation and salt diapirism, which commenced in the Early Cretaceous. We illustrate that the arrays grew by tip propagation of isolated fault segments, some of which linked during the Albian‐Cenomanian (i.e., 113–100.5 Ma, or the initial 11%–13% of their deformation history). Some arrays then reached their near‐final length within the subsequent ca. 77 Ma (or the next 69%–81% of their deformation history), while others attained this later, during the subsequent ca. 18 Ma (i.e., after 95% of their deformation history). During this time, the segments formed and then breached releasing and restraining stepovers, with the arrays as a whole growing by alternating periods of lengthening and throw accumulation, punctuated by phases of inactivity. Our results also show that scatter in the D‐L scaling of strike‐slip faults reflects the propagation, interaction, and linkage of individual segments.