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Petroleum Geological Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
Apart from the contour map showing lines of equal depth/elevation or thickness of the subsurface rock layers, there are different kinds of contour maps showing other characteristics as described below: A litho-facies map is a contour map showing the proportion of sandstone, shale, carbonate and other mineral content of the underground rock formation.A bio-facies map is a contour map showing the fossil content of the formation.An isopach map shows the thickness variation of underground formation; it connects the points of equal true thickness measured perpendicular to the layer.An isochore map shows the thickness of the layers from top to bottom along a vertical line; it connects points of equal vertical thickness.
The premature decay of rifting processes in the northern South China Sea (38–33.9 Ma): insight from 3D seismic and its interpretation of the Lufeng Sag of the Pearl River Mouth Basin
Published in Australian Journal of Earth Sciences, 2022
B. S. Ma, J. W. Ge, G. H. Wu, J. F. Qi, F. Yu, S. Chen, W. G. He
In the lower unit of the Enping Formation, its stratigraphy generally thickens toward the hanging-walls of rift-related faults (e.g. F3, F5, F6 in Figure 4); slightly wedge-shaped geometries are observed in the HZ5, HZ11 and LF13W depocentres. However, the stratigraphic geometry of the LF15 depocentre is nearly tabular, with a maximum thickness of about 580m (Figures 4d and 5b). In the isopach map of the lower unit, several differential characteristics are recognised (Figure 5b): (1) the stratigraphy is widespread in the North Sub-sag, but largely absent in the South Sub-sag; (2) the depocentres in the North Sub-sag are larger and thicker than those in the South Sub-sag; (3) three nearly E–W- or WNW-striking major faults (i.e. F3, F5 and F6) control the depocentres, all of which are more than 1000m thick; and (4) three major faults, the WNW-striking F1, NE- to ENE-striking F2 and NE-striking F4, control the depocentres to some extent, all of which are 500–1000m thick.