DOI: 10.5061/dryad.ffbg79d0w
title: Paleomagnetic constraint on the Age of the Shyok Suture Zone

description: The India-Eurasia collision is a key case study for understanding the
 influence of plate tectonic processes on Earth’s crust, atmosphere,
 hydrosphere and biosphere. However, the timing of the final India-Eurasia
 continental collision is debated due to significant uncertainty in the age
 of the collision between the Kohistan-Ladakh arc and Eurasia along the
 Shyok suture zone. Here we present paleomagnetic results that constrain
 the Karakoram terrane in northwest India to a paleolatitude of 19.9 ± 8.9
 °N between 93 – 75 million years ago (Ma). Our results show that the
 Karakoram terrane was situated on the southern margin of Eurasia in the
 Late Cretaceous. Our results indicate that the Kohistan-Ladakh arc and
 Eurasian continent had not converged until &lt; 61.6 Ma, placing a
 Paleocene older limit on the age of final closure of the Shyok suture
 zone. This suggests that the India-Eurasia collision in northwestern India
 likely occurred after the closure of the oceanic basin between the
 Kohistan-Ladakh arc and Eurasia. The Paleocene collision event affecting
 India that has been widely interpreted to represent the final
 India-Eurasia collision instead records the arc-continent collision
 between the Kohistan-Ladakh arc and the northern edge of India prior to
 the final India-Eurasia collision. The final India-Eurasia collision in
 northwest India most likely occurred after the closure of the oceanic
 basin between the Kohistan-Ladakh arc and Eurasia.
description: We collected 7–10 oriented
 core samples from 34 horizons distributed throughout the Saltoro Formation
 stratigraphy near Charasa for paleomagnetic analysis. Bedding orientations
 at each site were measured repeatedly over a 20–40 m along-strike, and the
 bedding orientation used for structural corrections is the mean of 5–15
 individual measurements. Andesite bedding horizons were identified using
 chilled upper surfaces of beds. Core samples were collected in the field
 using a water-cooled electric hand drill and oriented using an ASC
 Industries Pomeroy orienting fixture. Nonmagnetic brass tools were used to
 extract cores from the outcrop to prevent damaging the remanent
 magnetization of samples during sample collection. Optical microscopy was
 used to identify magnetic carriers and textural relationships within the
 samples. One specimen was cut from each core sample using an ASC
 Scientific dual-blade rock saw. The natural remanent magnetization was
 measured on a 2G Enterprises Superconducting Rock Magnetometer equipped
 with an automated sample handler (Kirschvink et al., 2008) inside a
 mu-metal magnetically shielded room in the MIT Paleomagnetism Laboratory
 applying a &lt;200-nT DC field. Specimens were subjected to stepwise
 alternating field (AF) and thermal demagnetization. AF steps were applied
 in increments of 2 mT up to 12 mT followed by thermal steps starting at
 100 °C and increasing up to 600 °C or 680 °C in variable interval sizes
 from a maximum of 100 °C and minimum of 2 °C close to the Curie
 temperatures of the suspected principal magnetic carriers (magnetite: 580
 °C, and hematite: 680 °C). Stable components of magnetization were
 isolated using principal component analysis (PCA)(Kirschvink, 1980) (see
 supplementary Table S2). Origin trending components were anchored to the
 origin and components were only fitted where the maximum angular deviation
 (MAD) was &lt;15°.
description: Software package used: PmagPy Tauxe, L., R.
 Shaar, L. Jonestrask, N. L. Swanson-Hysell, R. Minnett, A. A. P. Koppers,
 C. G. Constable, N. Jarboe, K. Gaastra, and L. Fairchild (2016), PmagPy:
 Software package for paleomagnetic data analysis and a bridge to the
 Magnetics Information Consortium (MagIC) Database, Geochem. Geophys.
 Geosyst., 17, doi:10.1002/2016GC006307.
description: # Paleomagnetic constraint on the Age of the Shyok Suture Zone The dataset
 contains the results of thermal demagnetization experiments. ##
 Description of the data and file structure Thermal demagnetization data is
 stored in separate files for different levels of analysis. Raw
 superconducting rock magnetometer data is saved in .UP and .stat files for
 each run at a given temperature step. Thermal demagnetization magnetic
 moment and directional data for each is sample is stored in .rmg files
 labelled by sample number. Data from each site can be imported into PmagPy
 using the .sam files.