<p>The Banded Iron Formation (BIF) in Bundelkhand craton (BuC) occurred as supracrustals associated with TTG&#8217;s, amphibolites, calcsilicate rocks, and quartzite within the east-west trending Bundelkhand tectonic zone (BTZ). The BIFs near Mauranipur do not show any prominent iron-rich and silica-rich layer band and are composed of garnet, amphibole, quartz, and magnetite. The volumetrically dominant monoclinic-amphiboles are grunerite in composition. X<sub>Mg</sub> of grunerite varies between 0.39-0.37. The garnets are Mn-rich, the X<sub>Spss</sub> of garnet ranges from 0.26-0.20, X<sub>Pyp</sub> and X<sub>Grs </sub>vary between 0.10-0.06 and 0.07-0.05, respectively. P-T pseudosection analysis indicates that by destabilizing iron-silicate hydroxide phases through a series of dehydration and decarbonation reactions, amphibole and garnet stabilized in BIF at temperature 400-450&#176;C and pressure 0.1-0.2 GPa.</p><p>Massive type BIFs have monazite grains that vary from 10 to 50 &#181;m in size, yield three distinct U-Th-Pb<sub>total</sub> age clusters. 10-20 &#181;m sized monazite grains yield the oldest age, 3098&#177;95 Ma. 2478&#177;37 Ma average age is obtained from the second group, which is relatively larger and volumetrically predominant. The third age group of Monaiztes gives an age of 2088&#177;110 Ma. ~3100 Ma monazite suggests the older supracrustal rocks of Bundelkhand craton, similar to those obtained from Singhbhum and the Dharwar craton. The 2478&#177;37 Ma age is constrained as the timing of metamorphism and stabilization of BuC. The third age group, 2088&#177;110 Ma probably associated with renewed hydrothermal activities, leading to rifting and emplacement of mafic dykes in BuC.</p>
Study on shear wave attenuation characteristics of shallow sediments in gas hydrate pilot production area of South China Sea
