The LB displays an overall positive free-air gravity anomaly (implying thin crust) with distinct axial lows (~20 mgal) aligned with axial segments (Fig. High-resolution seismic reflection and bathymetry data from LB evince rugged and substantially deformed basement between a variably thick sediment apron and a magmatically modified lower crust) and thus favoured an oceanic affinity of the crust with an underlying extinct spreading centre (see lineations in Fig. However, the extent of magnetic lineations as well as inferred rift durations in LB vary profusely from one study to another, indicating a pre-Deccan, ultra-slow, emplacement of axial seamounts over highly attenuated crust could be younger than Anomaly 28 (~62 Ma).Contrary to expectations, available seismic images neither corroborate a characteristic axial valley nor a relict magma chamber clearly underneath an axial segment, i.e., the Panikkar ridge.
The western passive margin of India inherits vital imprints of the Gondwana break-up and early evolution of the Indian Ocean, yet it is one of the least explored continental margins.
The groundmass is identical to the rest of the LB lava (Supplementary Fig. Typical occurrence of clinopyroxene and altered olivine grains before plagioclase in LB lava demonstrate that the likely crystallisation sequence was olivine–clinopyroxene–plagioclase.
Mineral chemical data of plagioclase from these lavas point towards their highly calcic nature having anorthite mole % values up to 90.
Our observations imply a relict subduction initiation event occurred in the Laxmi basin in the Late Cretaceous-Early Cenozoic that marks a significant Cenozoic plate reorganisation record in the northwest Indian Ocean.
New findings therefore warrant re-evaluation of the Gondwana breakup to account for the nascent subduction in the northwest Indian Ocean.
There were 104 women in the expectant group and 70 in the induction group (26 women allocated to induction preferred no treatment).