Strontium isotope stratigraphy in the Late Cretaceous: Numerical calibration of the Sr isotope curve and intercontinental correlation for the campanian

The white Chalk exposed in quarries at Lagerdorf and Kronsmoor, northwestern Germany, provides a standard section for the European Upper Cretaceous. The Sr-87/Sr-86 values of nannofossil chalk and belemnite calcite increase upward through 330 m of section, from less than or equal to 0.70746 in the Upper Santonian to greater than or equal to 0.70777 in the Lower Maastrichtian. The data define three linear trends separated by major points of inflection at stratigraphic heights in the section of 162 m (75.5 Ma) in the Upper Campanian Galerites vulgaris zone and at -6 m (82.9 Ma), just above the base of the Campanian in the Inoceramus lingua/Goniateuthis quadrata zone. The temporal rate of change of Sr-87/Sr-86 was constant through each of the linear segments of our isotope ''curve'' when viewed at the resolution of our average sampling interval (0.15 m.y.). Fine structure, if rear, may record brief (<100 kyr) excursions of (SrSr)-Sr-87-Sr-86 from values expected from the overall trends. In Lagerdorf, the boundary between the Santonian and Campanian stages, taken here as the level of first occurrence of the belemnite Gonioteuthis granulataquadrata, has an Sr-87/Sr-86 Of 0.707473 +/- 5. This is within error of the values of 0.707457 +/- 16 for this boundary in the U.S. western interior (base of the Scaphites leei III zone) and 0.707479 +/- 9 for this boundary in the English Chalk (top of the Marsupites testudinarius zone). In Kronsmoor, the boundary between the Campanian and Maastrichtian stages, taken here as the level of first occurrence of the belemnite Belemnella lanceolata, has an Sr-87/Sr-86 of 0.707723 +/- 4. This is within error of the values of 0.707725 +/- 20 for this boundary in the U.S. western interior (base of the Baculites eliasi zone) and 0.707728 +/- 5 for this boundary in the English Chalk (defined as in Germany)

Prodigious submarine landslides during the inception and early growth of volcanic islands

Volcanic island inception applies large stresses as the ocean crust domes in response to magma ascension and is loaded by eruption of lavas. There is currently limited information on when volcanic islands are initiated on the seafloor, and no information regarding the seafloor instabilities island inception may cause. The deep sea Madeira Abyssal Plain contains a 43 million year history of turbidites among which many originate from mass movements in the Canary Islands. Here, we investigate the composition and timing of a distinctive group of turbidites that we suggest represent a new unique record of large-volume submarine landslides triggered during the inception, submarine shield growth, and final subaerial emergence of the Canary Islands. These slides are predominantly multi-stage and yet represent among the largest mass movements on the Earth’s surface up to three or more-times larger than subaerial Canary Islands flank collapses. Thus whilst these deposits provide invaluable information on ocean island geodynamics they also represent a significant, and as yet unaccounted, marine geohazard

Nature and significance of a Cambro-Ordovician high-K, calc-alkaline sub-volcanic suite: The late- to post-orogenic Motru Dyke Swarm (Southern Carpathians, Romania)

SCOPUS: ar.jinfo:eu-repo/semantics/publishe