Abstract:
Our regional gravity and magnetic profiles spanning approximately -1220 km
and~1120 kmrespectively along Delhi - Chandigarh - Kiratpur - Sundernagar - Kullu
- Manali - Keylong - Sarchu- Pang - Rumtse- Upshi - Igu - Leh - Khardung La -
Panamik, Igu - Karu - Chang la - Durbuk profiles across all major structural elements
of NW Himalaya were duly processed and interpreted. Additionally, we include here
gravity and magnetic profiles across Indus Tsangpo Suture Zone (ITSZ) along Mahe-
Sumdo - Tso Morari.
Spectral analysis of projected gravity and magnetic data on straight profiles
followed by data decomposition led to main profiles and its components. It is done by
our own software. Then, our Stabilized Analytical Signal algorithm is applied on all
projected gravity and magnetic data and its components leading to estimates of depth
and horizontal coordinates of anomaly sources.
Continuous Wavelet Transform (CWT) method is applied to gravity and
pseudo-gravity data and its components, thereby leading to comprehensive depth
stacks.
Based on Phillips (2010), Analytical Signal of complete gravity, magnetic and
pseudo-gravity anomalies and its components along Delhi - Panamik, Delhi - Durbuk
and Mahe - Sumdo - Tso Morari profiles allowed us to asses the dip of thrust sheets
and faults coinciding with surface geological formations.
By considering all the inputs, crustal structure models were derived from
gravity and magnetic data along Delhi - Panamik profile. Our gravity derived crustal
structure equally emphasizes the deepening of Moho below Higher Himalaya to around
65 km and it shallows up under Aravallis to 40 km. The decollement in both sections
(gravity and magnetic cases) is around 9 - 12 km on an average. Partially melt zone is
inferred below Higher Himalaya zone in gravity derived crustal structure section.
The importance of variable density in terrain correction (Sastry et al., 2005) is
illustrated in our Mahe - Sumdo - Tso Morari profile. Additionally, presence of
ophiolites within Ladakh batholith is also inferred in our analysis of total field intensity
anomaly data along Rumtse - Upshi -Igu - Leh - Khardung la - Panamik, Rumtse -
Upshi -Igu - Karu - Chang la - Durbuk profiles.
