Combined gravity and magnetic modeling over Pavagadh and Phenaimata igneous complexes, Gujarat, India: Inference on emplacement history of Deccan volcanism

摘要: Abstract A large number of igneous intrusions related to the Deccan magmatism are exposed in western and central part Indian shield. Gravity magnetic (G–M) surveys over some these intrusive bodies depict gravity high bipolar anomalies as most characteristic signatures. The present G–M survey was carried out Pavagadh Phenaimata intrusives. Associated with complex, Bouguer anomaly shows an elliptical shaped relative about 40 mGal varies from South North between −800 nT 1200 nT. joint modeling reveals presence a dense mafic body (2.86 g/cm3). This is characterized by remanant magnetization; inclination (I) = ∼44° declination (D) = ∼160° may correspond 29R polarity chron magnetostratigraphy. Remanant magnetization together age data suggest that emplaced during end main phase Deccan. Over Pavagadh, circular lows −15 mGal −500 nT respectively reported for first time which surrounded 30 mGal 350 nT, respectively. deep-seated cone high-density (⩾3.0 g/cm3) gabbroic might extend up great depth. Its top surface reaches depth 10.0 km. Overlying this low-density (2.40 g/cm3) rhyolite, extends source low anomaly. It another (2.89 3.02 g/cm3) reverse direction (I = ∼38° D = ∼152°). modeled rhyolite (I = −32° D = 336°) deeper D = 340°) show normal polarity. Measured surrounding relates middle (29R) chron. Inferred then upper (29N), lower (30N) chrons. Therefore, magma forming complex covering major span eruption. model suggests chambers developed within higher crustal levels originated underlying through assimilation fractional crystallization (AFC).