Abstract-The Lonar crater in Maharashtra state, India, has been completely excavated on the Deccan Traps basalt (approximately 65 Ma) at approximately 570 ± 47 ka by an oblique impact of a possible chondritic asteroid that struck the preimpact target from the east at an angle of approximately [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] o to the horizon where the total duration of the shock event was approximately 1 s. It is shown by our early work that the distribution of ejecta and deformation of target rocks around the crater rim are symmetrical to the east-west plane of impact (Misra et al. 2010). The present study shows that some of the rock magnetic properties of these shocked target basalts, e.g., low-field anisotropy of magnetic susceptibility (AMS), natural remanent magnetization (NRM) ⁄ bulk susceptibility (v), and high-coercivity and high-temperature (HC_HT) magnetization component, are also almost symmetrically oriented with reference to the plane of impact. Studies on the relative displacements of K 3 (minimum) AMS axes of shocked basalts from around the crater rim and from the adjacent target rocks to the approximately 2-3 km west of the crater center suggest that the impact stress could have branched out into the major southwestward and northwestward components in the downrange direction immediately after the impact. The biaxial distribution of AMS axes in stereographic plots for the unshocked basalts transforms mostly into triaxial distribution for the shocked basalts, although transitional type distribution also exists. The degree of anisotropy (P¢) of AMS ellipsoids of the shocked basalts decreases by approximately 2% when compared with those of the unshocked target (approximately 1.03). The NRM ⁄ v (Am )1 ) values of the shocked basalts on the rim of the Lonar crater do not show much change in the uprange or downrange direction on and close to the east-west plane of impact, and the values are only approximately 1.5 times higher on average over the unshocked basalts around the crater. However, the values become approximately 1.4-16.4 times higher for the shocked basalts on the crater rim, which occur obliquely to the plane of impact. The target basalts at approximately 2-3 km west of the crater center in the downrange also show a significant increase (up to approximately 26 times higher) in NRM ⁄ v. The majority of the shocked basalt samples (approximately 73%) from around the crater rim, in general, show a lowering of REM, except those from approximately 2-3 km west of the crater center in the downrange, where nearly half of the sample population shows a higher REM of approximately 3.63% in average. The shocked target basalts around the Lonar crater also acquired an HC_HT magnetization component due to impact. These HC_HT components are mostly oriented in the uprange direction and are symmetrically disposed about the east-west plane of impact, making an obtuse angle with the direction of impact. The low-coercivity and low-temperature (LC_LT) components of both the unshocked...

The anisotropy of magnetic susceptibility (AMS) technique, combined with the analyses of satellite images and the geological structure, are examined on Lonar crater , a small, ~1.8-km-diameter impact crater in India, to evaluate the direction and obliquity of asteroid impact. The Advanced Spaceborne Thermal Emission and Refl ection Radiometer (ASTER) image (15-m resolution) of the ca. 52 ka Lonar crater in the subhorizontal Deccan basalt (ca. 65 Ma) shows that this simple, bowl-shaped impact crater has a near-circular rim with a circularity of ~0.95. Most of the highly refl ecting, continuous-ejecta blanket around the crater rim can be enveloped with an ellipse whose major E-W axis is coincident with the diameter of the crater rim and minor N-S axis is relatively displaced toward the west by ~200 m. The present ejecta distribution, which appears to be close to its pristine shape, extends to a distance of ~700 m in all the directions from the crater rim except to the west where it extends to a distance of a little more than 1 km. The circular shape of the crater rim, the E-W bilateral symmetry of the enveloping ellipse on the ejecta, and the greater extension of the ejecta toward the west appear to be the result of an oblique impact from the east with an angle of incidence of 30°-45° when compared with experiments. The AMS data suggest that the target basalts occurring at ~2 km west-southwest of the crater rim are highly shocked, as indicated by the random orientation of their K 3 susceptibility axes in comparison to the unshocked basalts at ~2 km east-southeast of the crater; the unshocked basalts show a bimodal distribution of susceptibility axes typical of lava fl ows. Moderate to strong westward shifts of the K 3 axes are seen for the majority of the shocked basalts on the crater rim and westsouthwest of the crater; the shocked basalts also indicate an oblique impact from the east when compared with modeling and experiments. A general lowering of degree of anisotropy of the Lonar shocked basalts (~1.01) compared to the surrounding unshocked basalts (~1.03) is found to be a characteristic feature of impact crater target rocks. Variation in attitudes of the basalt fl ows on the Lonar crater rim shows a bilaterally symmetrical distribution about an E-W axial plane, which includes quaquaversal dips of the fl ows all around the crater rim, except to the west where overturned dips of the basalt fl ows are seen. It appears that oblique impact and the symmetry in structural variations around the crater rim have a relationship for a small crater such as Lonar.

In order to quantify the Indian summer monsoon (ISM) variability for a monsoon dominated agrarian based Indian socio-economy, we used combined high resolution δ13C, total organic carbon (TOC), sediment texture and environmental magnetic data of the samples from a ~3 m deep glacial outwash sedimentary profile from the Sikkim Himalaya. Our decadal to centennial scale records identified five positive and three negative excursions of the ISM since last ~13 ka. The most prominent abrupt negative ISM shift was observed during the termination of the Younger Dryas (YD) between ~11.7 and 11.4 ka. While, ISM was stable between ~11 and 6 ka, and declined prominently between 6 and 3 ka. Surprisingly, during both the Medieval Warm Period (MWP) and Little Ice age (LIA) spans, ISM was strong in this part of the Himalaya. These regional changes in ISM were coupled to southward shifting in mean position of the Intertropical Convergence Zone (ITCZ) and variations in East Asian monsoon (EAM). Our rainfall reconstructions are broadly in agreement with local, regional reconstructions and PMIP3, CSIRO-MK3L model simulations.

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