The Cretaceous is characterized by major environmental perturbations at the Earth's surface, including accelerated global warming and Oceanic Anoxic Events (OAEs). Continental chemical weathering may have played a crucial role in triggering OAEs. To evaluate the dominant controls on hinterland chemical weathering throughout the Cretaceous, and to assess whether an acceleration of continental weathering could have triggered OAE 2, this study examines temporal variations in the degree of continental weathering along the eastern Asian continental margin. We calculated the W value, a chemical weathering index derived from major element composition. The overall increasing trend in W values from the Aptian to the Campanian is similar to the pattern of global paleotemperature fluctuations inferred from oxygen isotopes of fossil fish teeth and benthic foraminifers and atmospheric CO 2 concentration. High-resolution measurements interval reveal an abrupt increase in hinterland weathering before the onset of OAE 2 that ceased simultaneously with its termination. Combining previous studies from the Tethys and North Atlantic oceans with our data from the western Pacific margin indicates that enhanced hinterland weathering during the middle Cretaceous was a global and pervasive phenomenon that may have triggered OAE 2.
Detrital mineral grains preserve a critical record of the magmatic history associated with Rodinia breakup. Here, we present U-Pb geochronology and Hf isotope data from igneous and detrital zircon and detrital monazite in late Neoproterozoic to early Cambrian Iapetan rift successions of the Oak Hill and Saint-Roch Groups, along the Laurentian margin in the southern Québec Appalachians. While all sedimentary rocks contain dominant Mesoproterozoic detrital populations, the basal Pinnacle Formation sandstone yields Cryogenian-Ediacaran (710–625 Ma) detrital zircon grains that document a previously poorly constrained magmatic episode, likely associated with Rodinia breakup. These Neoproterozoic detrital grains display chondritic to positive εHf values, similar to igneous zircon included in the underlying alkaline Ediacaran Tibbit Hill Formation volcanic rocks. The Hf isotopic signatures from both formations are consistent with derivation from a similar mantle-derived source. We suggest that the sources of these rare 710–625 Ma detrital zircon grains may be concealed within Laurentian basement beneath the Northern Appalachians, though further work is needed to constrain the magmatic history of Iapetan rifting in this region.
High-enthalpy geothermal systems in western Türkiye are among the most productive geothermal provinces worldwide and supply a significant portion of the country's renewable electricity generation. Over the past two and a half decades, magnetotelluric (MT) surveys have played a central role in geothermal exploration across the Aegean extensional province, providing critical constraints on subsurface resistivity structures associated with clay caps, reservoirs, and fluid pathways. This chapter reviews the geological framework and exploration experience of high-enthalpy geothermal systems in western Türkiye, positioning the country as Europe's leading geothermal electricity producer and the fourth worldwide in installed capacity. This chapter emphasizes MT-constrained conceptual models, their validation through drilling, and lessons learned from exploration successes and interpretation challenges. This chapter highlights transferable insights for geothermal exploration in both extensional and volcanic geothermal provinces worldwide, using western Türkiye as a natural laboratory for MT-based geothermal exploration.
The International History of Geological Sciences Commission (INHIGEO) was founded some 60 years ago in 1967; few women were invited to join the ranks in the 20 th century. Three women out of 31 delegates were invited to attend the first INHIGEO conference held at the 23rd International Geological Congress in Yerevan, Armenia: two from the Soviet Union, one from Britain: Irina V. Batjushkova, Joan M. Eyles, and Aleksandra I. Ravikovitch. The numbers barely increased during the first decades. Only Ravikovitch made the higher Bureau briefly at the 1972 Montreal International Geological Congress meeting, with two further Corresponding members elected: Antonina Halicka and Ekaterina A. Radkevich. Later in the 1980s to 90s, American Ursula Marvin and Italian Nicoletta Morello made their mark: the former twice being elected Secretary-General, the latter as INHIGEO conference organiser. In the 21 st century, female membership increased significantly and INHIGEO had further women secretaries-General and gained its first female president, vice presidents and other long-standing members who have contributed significantly; early career members were chosen.
The basement of the Alpine-Himalayan mountain belt between the Alps and Iran preserves evidence of multiple tectonic events within distinct microcontinental blocks. However, the distribution and tectonic significance of the Late Neoproterozoic-Early Cambrian (“Cadomian”), Ordovician (“Cenerian”), Carboniferous (“Variscan”), and Permian-Jurassic (“Cimmerian”) tectonic stages remain incompletely understood. Based on geochronological and high-pressure/low temperature datasets in context with geological observations from the Alps to Iran, we show the key stages along northern Gondwana. Ediacaran-Cambrian arc systems and associated ophiolites forming the basement of the future Alpine-Himalayan belt. The western part of the belt was affected by Ordovician arc systems, but also by rift systems creating a flare-up of felsic magmatism, whereas in the east Silurian plume systems evolved related to the opening of a branch of the Paleotethys Ocean. Late Devonian and Carboniferous high-pressure metamorphism, felsic magmatism and associated migmatites can be traced from Alps towards to the Arax fault in NW Iran, whereas in Iran bimodal magmatism evolved in the Sanandaj-Sirjan Zone in a Carboniferous rift. On the other hand, 40 Ar/ 39 Ar geochronology provides evidence for orogenic metamorphism arguing for Variscan tectonic events in Central Iran. Furthermore, in contrast to previous models, Cimmerian metamorphism affected substantial portions of the Cimmerian microcontinent and is superimposed on Variscan tectonothermal events.
