PT  - JOURNAL ARTICLE
AU  - Mortimore, Rory N.
TI  - Chalk: all we need is a fracture log!
AID  - 10.1144/qjegh2021-031
DP  - 2022 Feb 01
TA  - Quarterly Journal of Engineering Geology and Hydrogeology
PG  - qjegh2021-031
VI  - 55
IP  - 1
4099  - http://qjegh.lyellcollection.org/content/55/1/qjegh2021-031.short
4100  - http://qjegh.lyellcollection.org/content/55/1/qjegh2021-031.full
SO  - Quarterly Journal of Engineering Geology and Hydrogeology2022 Feb 01; 55
AB  - Chalk fracture logging is reviewed in the context of the broader geology needed to build conceptual ground models. Examples of drilling damaged core illustrate the many issues faced by core loggers including identification of marker beds (marl seams, hardgrounds, flint bands, fossil shell beds) and the ‘interpretations’ necessary to complete a fracture log. Stratabound fractures impart a special style of fracturing to each Chalk formation. Lithology is a key factor in development of fracture style where marl seams control inclined conjugate fracture sets, development of listric growth faults and interbed slides. Lateral changes in lithology and thickness and consequent controls on fracture evolution are related to intra-Chalk tectonic episodes and tectonic setting with onshore interpretations supported by offshore seismic profiles. Strike-slip faults are illustrated in the Chalk cliffs of the Sussex coast. Fracture log reports should highlight special features such as shear zones and use annotated core photographs to illustrate issues requiring discussion.