AsianScientist (Jul. 2, 2018) – A research group in the US has used satellite technology to gain a better understanding of the rocks that make up the Himalayan mountain range. Their study is published in Geosphere.
The Himalayan mountain range includes some of the youngest and most spectacular mountains on Earth. However, the rugged landscape can keep scientists from fully understanding how these mountains formed.
In the present study, researchers at the University of California, Berkeley and the Mars Space Flight Facility at Arizona State University collaborated to study the rocks of the Himalayan mountain range. They relied on the fact that every mineral has a unique spectral ‘signature,’ where some parts of the thermal infrared spectrum are absorbed and other parts are reflected.
Rocks are made of different combinations of minerals, so when all these mineral signatures are combined, they reveal the rock type. To tell different kinds of rocks apart, the researchers translated these signals into red, green or blue imagery. This created a distinguishable color for each rock type that can be used to map the distribution of rocks throughout the region.
To double-check that the colors they were mapping truly represented the rock type predicted by the imagery, the researchers obtained physical samples from accessible locations in the study area and measured the spectral signatures of each rock using a thermal emission spectrometer in their laboratory. They were able to match these laboratory signatures to those collected from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on the Terra satellite that orbits Earth.
“There is some variation between the lab and ASTER spectral signatures due to different factors like weathering and the averaging area, but overall the match between them was surprisingly consistent,” said study co-author Dr. Alka Tripathy-Lang of the University of California, Berkeley.
The map the scientists created revealed some interesting geology. They were able to clearly see ‘suture zones’—ancient seafloor pushed up and exposed during the collision between India and Eurasia—as well as subtle differences in the granitic mountains that indicated different phases of formation. They were also able the observe the intersection of two massive fault systems, the Karakoram and Longmu Co faults.
“These fault systems are hugely important to the story of the Himalayan-Tibetan collision, and determining the way these systems have evolved and how they interact is critical for understanding this part of the Himalayan mountains,” said Dr. Wendy Bohon of Arizona State University, who co-authored the study.
The article can be found at: Bohon et al. (2018) Structural Relationship Between the Karakoram and Longmu Co Fault Systems, Southwestern Tibetan Plateau, Revealed by ASTER Remote Sensing.
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Source: Geological Society of America; Photo: Wendy Bohon.
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