Field work in Californian hills
Iselin Tjensvold is currently a Masterstudent –supervised by Christian Hermanrud (Prof II position financed by FME SUCCESS at UiB). In her Master thesis she is exploring the possibility of categorizing sand injectites based on the basin setting they occur.
At the University of Bergen, she has access to regional 3D broadband seismic data available (acquired by CGG) from the Northern North Sea. In this dataset she will study sand injectites formed at inverted massive margins.
Iselin was invited as a field assistant for Antonio Grippa (research fellow at The University of Aberdeen, UK) in the Panoche and Tumey Hills september this year. These hills represent one of the best exposed sandstone intrusion networks in the world. Deep water depositional sands were remobilized at a convergent basin setting and hence the observations from this fieldtrip are most relevant and valuable in the context of the link between outcrop and seismic interpretation.
Iselins conclusions from her field trip are:
• Sandstone intrusions create large networks, establishing pressure communication between sand bodies that were not connected originally, and hence new migration routes for gas or fluids are constructed.
• It is important to keep in mind that sandstone intrusions may not only be interconnected to each other, but also other sand bodies which they cross-cut.
• Sandstone intrusions in the Panoche and Tumey Hills formed at the continental margin, and not within the accretionary prism. However, based on observations from Winslow (1983) in Chile, injectites occurring in relation to the compression within the accretionary prism should not be excluded from possible geological settings where sand injectites occur.