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The high-amplitude wide magnetic anomaly that covers a large area of the north-eastern – central Adriatic Sea in the Croatian offshore is ∼100 km wide and extends NW–SE for ∼350 km. The anomaly is located between the Dinarides and Apennines chains, in an interesting geodynamic scenario. The presence of intruded gabbroid rocks in the Croatian archipelago also contributes to making this intriguing and still not extensively investigated anomaly potentially significant to the geologic and geophysical context in which it is located. In this work, we model the Bouguer and magnetic anomalies across the Adriatic Sea. The 2D geophysical modeling was produced across four cross sections considering surface heat flow data to calculate the Curie depth. The magnetic susceptibilities and densities used for the synthetic bodies are in agreement with the literature and with those derived by previous models. The results suggest the presence of an uplifted magnetized basement with high magnetic susceptibility (0.075 SI units) to be the main contributor to the observed magnetic anomaly. This magnetic susceptibility is interpreted as representative of a gabbroid-intruded basement. The high-susceptibility basement is in lateral continuity with a relatively low susceptibility basement (0.025–0.038 SI units). The results of the geophysical modeling are compared with a conceptual geological model realized from the integration of surface, well and geophysical data, the latter concerning seismic, tomographic, magnetic and gravimetric anomalies and heat flow data. These data have been merged in an integrated data-base using MOVE software, and the geophysical modeling was performed using GM-SYS. The comparison allowed to confirm the hypothesis that the magnetic anomaly is related to the basement and to its position in the complex geodynamic evolution of the Apennines–Adriatic–Dinarides system.

I investigate large-scale deep crustal structures of the Nankai subduction zone and neighboring region using regional magnetic and gravity anomalies, heat flow measurements, and earthquake hypocenters. It is found that ages, dip angles, and geothermal states of the subducting slab have direct influences on mantle wedge serpentinization. The weakest serpentinization observed in the Nankai forearc region is associated with the youngest downgoing plate of the Shikoku Basin. Conspicuous gravity anomalies identified in the forearc region are coincidental spatially with magnetic anomalies after the reduction to the pole, a mathematical procedure that helps relocate magnetic sources and boundaries, and allows us to more easily interpret magnetic data. It is argued that these patches of magnetic and gravity anomalies are caused by the same sources of anomalous density and magnetization, and are linked directly to preexisting structures such as magnetic anomalies and their boundaries in the subducting oceanic crust. Since the gravity and magnetic anomaly patches are found to be closely related to interplate seismogenic behaviors in the Nankai subduction zone, I suggest that major magnetic boundaries in the Shikoku Basin are likely weak places for slab tears that trigger seismic segmentations along the subduction zone. Application of the Parker–Oldenburg algorithm to Bouguer gravity anomalies yields a 3D Moho topography. Curie-point depths are also estimated from the magnetic anomalies with reduction to the pole using a windowed wavenumber-domain algorithm. Window sizes are found to have little effects on the average Curie-point depths other than lowering lateral resolutions. A wide zone of deep Curie depths is identified in southwest Japan, relating to strong influence from the subduction of the relatively young and warm Shikoku Basin crust of the Philippine Sea plate. Curie depths so obtained can be correlated well with heat flow measurements, which cluster around a theoretical curve when the average thermal conductivity is about 3.0 W/(m °C). Using constraints from both Curie depths and heat flow, I also model the shallow geothermal field of the subduction zone. Earthquake hypocenters plotted against Moho and Curie depths and geothermal fields on three transects confirm early studies that downdip limits of seismogenic zones along the Nankai plate boundary do not extend down to the island arc Moho and their temperatures are more or less close to 350 °C. Geothermal field has direct influences on earthquake distributions in the overriding island arc and accretionary prism, within the subducting oceanic lithosphere, and along the interplate boundary.

The passive continental margin of western India and the adjacent offshore region are associated with a transitional type thinned crust. It contains several sedimentary basins where substantial recoverable oil/gas reserves exist. The northern Cambay graben, northern and eastern parts of the Bombay offshore and the Konkan coast region that are situated close to western margin exhibit reasonably high heat flow and geothermal gradients beneath which the asthenosphere is upwarped to a depth of 30–70 km. Temperatures at the depth of 3 km are estimated to be in the range of 105–260°C. Curie depth analysis from MAGSAT studies in an area between latitudes 11°N and 19°N and longitudes 65°E and 73°E also indicates a high geothermal gradient of about 30°C/km within the upper crustal column. We suggest that the occurrence of oil and gas in these areas may be due to catastrophic and geodynamic events which took place in the last 130 Ma. India’s super-mobility, continental breakups, possible bolide impact and Deccan volcanic episode at the western margin resulted in substantial lithospheric heating, accompanied by subcrustal melting and rise of isotherms, to eventually enhance the hydrocarbon maturation process. The study indicates that all other sedimentary basins situated on the western margin are also thermally mature and may have high potential for the occurrence of hydrocarbons.

One-dimensional spectral analysis of aeromagnetic data over the Anambra Basin, which is a subsidiary depression within the Benue Trough of Nigeria, was made to map the sedimentary thickness variations and the Curie temperature isotherm. Sedimentary thickness (depth to the basement) varies between 0.9 and 5.6 km, while depth to the Curie temperature isotherm varies between 16 and 30 km below the mean sea level. The result also shows that the Curie temperature isotherm within the basin is not a horizontal level surface, but is undulating, and the geothermal gradients associated with it range between 20 and 35 °C/km.

A correlation study among Pn velocity distribution, surface heat flow and other related thermal parameters for Southern Indian Shield reveals that Pn velocity decreases significantly in the regions where regional heat flow and Moho temperatures are high. These areas are associated with shallow Curie depth and thin lithosphere. The observed variation in Pn velocity beneath Western part of Peninsular India could be explained due to pressure-temperature effect. However, beneath the Cuddapah basin it is not merely due to pressure-temperature difference at upper most mantle but lateral inhomogeniety is also responsible for it.