Depth to Bedrock: Basement Rock Mapping

Depth to Bedrock: Basement Rock Mapping

Description

Bedrock or basement rock is the hard, solid rock that underlies surface materials such as sand, gravel, or other unconsolidated rocks. They are consolidated rocks (tightly bound) and solid. They are usually extensive and are in some places deeply buried however in some places, they can be exposed on the surface.  The upper boundary of the bedrock tends to be more weathered than the deeper part of the bedrock usually because they are the part that get easily exposed to the factors that contribute to weathering.

The overlying earth materials are usually loose and unconsolidated sediments which may be derived from either the weathered basement or particles deposited from elsewhere.

The characteristic description of basement rock can vary slightly or greatly depending on locations and other associated geologic conditions. The bedrock composition, the quality of bedrock can differ significantly. The depth to bedrock head can differ from zero to few tens of kilometers, the topography can also be mildly lateral and vary greatly sometimes forming basins.

A good understanding of the bedrock is principal to many areas of human endeavors on earth. Different characteristic qualities of the bedrock are important at different points and time of human activities.

 

Infrastructural projects, buildings, roads, railroads, bridges, airports, Highrise buildings all depends greatly on the understanding of quality, topography, and the depth to the bedrock. Building underground facilities such as tunnels, repositories (storage facilities) with the ground would require an understanding of the bedrock.

Other areas where the understanding of the bedrock is important are.

  1. Mining – extraction of different solid minerals (Lead, Zinc, Iron, Gold, Copper etc) and hydrocarbons (natural gas, oil and coal).
  2. Groundwater extraction - Characterization of groundwater aquifers in bedrocks especially in fractured crystalline rocks.
  • Environmental Projects – mapping pathways for the analysis of groundwater and contaminant flow
  1. Resource planning and Management projects

At Hephzibah Geosolutions, we have been involved with projects on bedrock mapping and below is a case study of a project by a developer.

Case Study

XYZ company are hoping to do a private paved road within their property which is a hilly terrain with very uneven topography. They are looking to establish the best part of their property which can be chosen for the road. They want an area where the basement rock would be of least resistant to the development project that they are hoping to start, they would probably prefer location where excavation can be done easily and avoid rock blasting or drilling as much as possible.

Geophysical Investigation

Our team of experts were able to help by carrying out an integrated geophysical exploration. Two geophysical methods were employed for this project: the audio frequency magneto-telluric method and the ground penetrating radar. Data acquisition traverse lines were run both parallel and across the prospective areas of the property.

Results from the 2D profile plots was able to establish the topography of the basement rock at different locations within the property. The study established locations where the basement rocks are closer to the surface with uneven relief, locations with deeper basement rock and locations that have a gently sloping basement rock. Recommendations was made based on the objective of their project and the geophysical findings.

 

At Hephzibah Geosolutions, we employ a multi-method approach to produce 2D profiles or 3D surface models that outlines the bedrock topography. We try to understand your project and make suggestions of best geophysical techniques and help in carrying out detailed geophysical surveying for your project. Contact us today: 520-451-5976 or email us: info@hgeosolutions.com