Abstract The paper documents the process of proclaiming International Geodiversity Day as a grassroots initiative of the Earth science community for the benefit of our present civilization and for future generations. The huge support that this initiative has gained among scientists around the world has contributed to the rapid circulation of documents necessary to establish an international day at the UNESCO Forum. The paper presents the timeline of this process of proclaiming International Geodiversity Day, its implications and the course of the first celebrations in 2022.

Abstract An understanding of long-term climate variability may provide a valuable perspective on the possible response of human societies to modern climate change. The present study, based on geochemical and sedimentological analyses on well dated (using AMS 14 C and optically stimulated luminescence (OSL) dates) alluvial sediments from Sina River basin (in Maharashtra, central India), provides a detailed understanding of the complex interplay between climate and cultural dynamics during the Late Holocene. The radiocarbon dates of the organic residues from the potsherds represent the Medieval period ( c. 1.6–0.95 cal ka BP), whereas the OSL sample shows an age of c. 7.5 ± 0.4 ka. Further, several cultural objects (e.g. potsherds, shell bangles, and copper artefacts) available at the site were also investigated in order to understand the extent of human activity in the region. The temporal changes in the proxies along with the abundance of cultural materials in the fluvial section during the Medieval period suggest that the human population attempted to adapt against the fluctuating climate conditions. The regional comparison of geo-archaeological datasets shows that the pronounced weakening of the monsoonal rainfall during the Late Holocene coincides with the disruption, migration and resettlement of indigenous societies, deciphering the possible impact of climate on human settlement.

ABSTRACT The Appalachian Mountains were formed through multiple phases of Paleozoic orogenesis associated with terrane accretion. The timing, tempo, and significance of each event in New England are obscured by overprinting, the limits of geochronologic tools, and differences between lithotectonic domains. We present new monazite and xenotime geochronology, 40 Ar/ 39 Ar thermochronology, and major- and trace-element thermobarometry from major tectonic domains in southern New England and across multiple structural levels. These data show contrasting pressure-temperature-time ( P-T-t ) paths across tectonic domains and highlight eastward metamorphic overprinting associated with younger tectonic events. Our data and geochemical proxies suggest two major periods of crustal thickening, ca. 455–440 Ma and 400–380 Ma, and a heterogeneous record of thinning/exhumation. Ordovician (Taconic) crustal thickening postdates the interpreted accretion of the Moretown terrane by ~20 m.y. and may have been related to shallow subduction after subduction polarity reversal. Subsequent cooling and exhumation (440–430 Ma) may have been related to the end of the Taconic orogeny and opening of the Connecticut Valley basin. (Neo)Acadian tectono-metamorphism is recognized in accreted terranes of New England and is absent in the Taconic block. Amphibolite- to (high-pressure) granulite-facies metamorphism, slow cooling, and protracted anatexis ca. 400–340 Ma support the existence of a long-lived orogenic plateau in southern New England. Exhumation, which began at 340–330 Ma, may have involved ductile (channel) flow. The boundary between continental Laurentia and accreted terranes has been reactivated at multiple times and is presently manifested as a 12–15 km Moho step. At the latitude of our samples, Alleghanian-age tectonism (ca. 310–285 Ma) was limited to retrograde metamorphism, and relatively minor loading and exhumation in the vicinity of the Pelham dome. Our results highlight the sensitivity of the integrative petrochronologic approach and the transition of the eastern margin of Laurentia from terrane accretion to the formation of a high-elevation plateau.

ABSTRACT The late early to middle Miocene period (18–12.7 Ma) was marked by profound environmental change, as Earth entered into the warmest climate phase of the Neogene (Miocene climate optimum) and then transitioned to a much colder mode with development of permanent ice sheets on Antarctica. Integration of high-resolution benthic foraminiferal isotope records in well-preserved sedimentary successions from the Pacific, Southern, and Indian Oceans provides a long-term perspective with which to assess relationships among climate change, ocean circulation, and carbon cycle dynamics during these successive climate reversals. Fundamentally different modes of ocean circulation and carbon cycling prevailed on an almost ice-free Earth during the Miocene climate optimum (ca. 16.9–14.7 Ma). Comparison of δ 13 C profiles revealed a marked decrease in ocean stratification and in the strength of the meridional overturning circulation during the Miocene climate optimum. We speculate that labile polar ice sheets, weaker Southern Hemisphere westerlies, higher sea level, and more acidic, oxygen-depleted oceans promoted shelf-basin partitioning of carbonate deposition and a weaker meridional overturning circulation, reducing the sequestration efficiency of the biological pump. X-ray fluorescence scanning data additionally revealed that 100 k.y. eccentricity-paced transient hyperthermal events coincided with intense episodes of deep-water acidification and deoxygenation. The in-phase coherence of δ 18 O and δ 13 C at the eccentricity band further suggests that orbitally paced processes such as remineralization of organic carbon from the deep-ocean dissolved organic carbon pool and/or weathering-induced carbon and nutrient fluxes from tropical monsoonal regions to the ocean contributed to the high amplitude variability of the marine carbon cycle. Stepwise global cooling and ice-sheet expansion during the middle Miocene climate transition (ca. 14.7–13.8 Ma) were associated with dampening of astronomically driven climate cycles and progressive steepening of the δ 13 C gradient between intermediate and deep waters, indicating intensification and vertical expansion of ocean meridional overturning circulation following the end of the Miocene climate optimum. Together, these results underline the crucial role of the marine carbon cycle and low-latitude processes in driving climate dynamics on an almost ice-free Earth.