loading page

On the emplacement of the impact melt breccia at the Dhala Impact structure, India.
  • +1
  • Gaurav Joshi,
  • Pradyut Phukon,
  • Amar Agarwal,
  • Arun Kumar Ojha
Gaurav Joshi
Indian Institute of Technology Kanpur

Corresponding Author:[email protected]

Author Profile
Pradyut Phukon
Indian Institute of Technology Kanpur
Author Profile
Amar Agarwal
Indian Institute of Technology Kanpur
Author Profile
Arun Kumar Ojha
CSIR-National Geophysical Research Institute
Author Profile

Abstract

We investigate the magnetic fabrics of Impact melt breccia at the Dhala impact structure to understand its emplacement mechanism. Our results show that the pseudo-single domains of Ti-poor magnetite and Ti-hematite are the prime magnetic carriers in the impact melt breccia. The magnetic fabrics from most sites reveal a general westward flow of impact melt breccia (IMB), with magnetic lineations of individual specimens trending between NW and SW. This indicates the emplacement of IMB in a semi-molten state with temperatures below c. 1500°C, which is the melting point of Ti-magnetite. Occurrence of poorly sorted clasts implies that IMB was emplaced as surficial flow rather than aerial. The variation in the dips of magnetic fabrics among individual specimens from a site resembles a pyroclastic flow rather than a ground-hugging volatile- and melt-rich flow. We, therefore, suggest that the IMB at Dhala was ballistically ejected and then moved in a semi-molten state as surficial pyroclastic-like flow with temperatures below c. 1500°C. Most flow vectors aligned between NW-SW, may represent a dominant westward excavation flow of the IMB (rather than radially outward flow), which may be activated by an east-to-west directed impactor striking at an impact angle below 50°.