Identification of the members of the Maastricht Formation in Valkenburg, the Netherlands

Identification of the members of the Maastricht Formation in Valkenburg, the Netherlands

Dwarkasing, A.S.
Lie-A-Fat, J.

Ngan-Tillard, D.J.M. (mentor)

Civil Engineering and Geosciences

Geoscience & Engineering

2012-07-09

In the city of Valkenburg a new underground parking garage is being built next to the Hema. For this project four boreholes were drilled in the Maastrichtian limestone. These cores were described and tested at the laboratory of the department of Geoscience and Engineering of Delft University of Technology to obtain the geotechnical properties of the limestone that are relevant to the car park construction. In this thesis, the cores are analyzed to obtain information about the local (structural) geology. This geological information is necessary to determine in which member of the Maastrichtian limestone the car park will be build and if there are faults in this area that can influence the project. The Maastricht Formation is divided into six members, each having its own characteristics. To determine from which member of the Maastricht Formation the cores are, data from various sources has been interpreted and integrated. The geotechnical description and testing of the cores made by TU Delft have been used. Gamma-ray logs have been recorded (by others) in three of the boreholes made for the car park project. They have been segmented, by the authors of this report, in the hope to determine boundaries between the different members. Also XRF analyses for the mineral content; analyses of fossil remains, limestone color and cherts have been conducted. Their results have been correlated with information found in the literature for each member. The following conclusions have been drawn. Very few macro-fossils have been found in the cores. From this information, the presence of members known for their high content in fossils is excluded, so this conclusion confirms that the cores are not drilled in the Meerssen member. The specific characteristics of the cherts confirmed the occurrence of some members of the Maastricht Formation in the Valkenburg cores. The pipe shaped cherts confirmed the Emael member, and the brown grey cherts confirmed the Gronsveld or the Valkenburg. From the XRF results the percentages of silica was less than 15% for the deepest samples taken in the core linings and according to literature the Valkenburg member has a silica content of approximately 15%, confirming that the Valkenburg member is not reached. The XRF analysis gave unexpected results. Some limestone cores were found to contain gypsum and/or have a silica content higher than what has been reported in the literature. The patterns observed on the gamma logs could not be explained by the XRF results. They are not well understood. Some could be observed in two boreholes and not in the third one. The authors concluded that the cores have been drilled in the Emael to the Gronsveld member. They did not reject the possibility that the members of the Maastrichtian found in Valkenburg do not have the same characteristics as the members found elsewhere in Limburg, for example, Maastricht. During the interpretation of the provided gamma ray logs, some difficulties were encountered. The XRF results stated that the high gamma ray peaks are not caused by higher potassium contents, which is often expected. If higher potassium contents are excluded, the expectation is that the peaks are due to the presence of organic matter, but this was not confirmed by the XRF either. Because of variations in the gamma ray logs and the core descriptions, it is difficult to reject the presence of any small fault intersecting the future car park. Note that the observed variations could well be due to local variations in the sedimentation conditions.

Valkenburg
limestone
Maastricht Formation

http://resolver.tudelft.nl/uuid:ddf9ecd2-7632-4a09-9ef5-8a1748d190fc

2015-07-09

Student theses

bachelor thesis

(c) 2012 Dwarkasing, A.S.
Lie-A-Fat, J.