TO THE 90TH ANNIVERSARY OF IVAR MURDMAA

On August 6, 2021, the chief researcher of the IO RAS, Doctor of Geological and Mineralogical Sciences, Professor Ivar Oskarovich Murdmaa turned 90 years old. The main focus of I.O. Murdmaa is the study of bottom sediments of seas and oceans, their lithology, mineralogy, deposition processes, facies and formations, the theory of oceanic sedimentogenesis. He first distinguished marine volcanoterrigenous sediments and described the facies variability of modern sediments of island arcs. Ivar Murdmaa is known for his studies in mineralogy of oceanic sediments, processes of pelagic sedimentogenesis and associated iron-manganese nodules formation. Studying sediment formation in rift zones of mid-ocean ridges, he identified a new genetic type of sediments named edaphogeonus sediments, elaborated mineralogical criteria for their recognition and formation processes. In recent years I.O. Murdmaa is actively developing the theoretical concept of "sedimentosphere", paying special attention to a new direction – the study of the erosion-accumulative activity of bottom currents and the formation of contourites.

Geochemistry and Petrogenesis of Basic Paleogene Volcanic Rocks in Alamut Region

Structurally, the study area belongs to the tectonic range of the Central Alborz. The rocks were analyzed to detect main elements as well as rare and rare earth elements. Based on microscopic studies, the rocks in the region include basalt, trachyandesite and basaltic andesite with alkaline geochemical properties. According to geochemical studies, the early magma was affected by Nb, Ti, Ta, Eu negative anomalies, the enrichment of Rhizosphere rocks of rare earth elements (LRRE), high LREE/HREE ratio and low K/Nb ratio and high ratios of Th/Nb, La/Nb, Ba/Nb, Zr/ Nb magmatic contamination. The early basaltic magma has been formed of a garnet lherzolite mantle with phlogopite/pargasite by metasomatism at a pressure of 2.5-5.3 GPa at depths of more than 80-150 km. Structural evidence suggests the formation of these volcanic rocks in intercontinental rift zones. The formation of these rocks can be attributed to the effects of intercontinental extensional phases in deep faults during Eocene Alpine orogeny phases.

Prospectivity of the Triassic successions of the North West Shelf of Australia: New insights from a regional integrated geoscience study

The North West Shelf (NWS) of Australia is a prolific hydrocarbon province hosting significant volumes of hydrocarbons, primarily derived from Jurassic and Cretaceous targets. A new regional, integrated geoscience study has been undertaken to develop insights into the paleogeography and petroleum systems of Late Permian to Triassic successions, which have been underexplored historically in favor of Jurassic to Cretaceous targets. Within the NWS study area, graben and half-graben depocenters developed in response to intracratonic rifting that preceded later fragmentation and northward rifting of small continental blocks. This, coupled with contemporaneous cycles of rising sea levels, brought about the development of large embayments and shallow, epeiric seas between the Australian continental landmass and outlying continental fragments in the early stages of divergence. Key elements of the study results discussed herein include the study methodology, the paleogeographic and gross depositional environment mapping, and the reservoir and source kitchen modeling. The study results highlight the presence of depocenters that developed within oblique rift zones due to regional Permo-Triassic strike-slip tectonics that bear compelling similarities to modern-day analogues. These intracratonic rift zones are well-known and prominent tectonic features resulting from mantle upwelling and weakening of overlying lithospheric crust, initiating the development of divergent intraplate depocenters. The comprehensive analysis of these depocenters from a paleogeographic and petroleum system perspective provides a basin evaluation tool for Triassic prospectivity.

Geology of Nubia and Surrounding Regions

Nubia occupies a low, interior plain extending from southern Egypt to central Sudan. It is surrounded by high plateaus and mountains on all sides except the north. Across this plain flows the Nile River. The bedrock geology is dominated by metamorphic and igneous rocks of the mainly Precambrian to Paleozoic Basement Complex, and sedimentary rocks of the Cretaceous Nubian Sandstone Formation. Cataracts and rapids exist wherever the Nile River flows over Basement Complex rocks. The bedrock is blanketed in many areas by unconsolidated alluvial, lacustrine, and especially eolian sediments of mostly Quaternary age. The tectonically active Red Sea and East African rift zones are responsible for Cenozoic and still ongoing volcanism and seismicity in the Nubian region with additional tectonism resulting from uplift along the Nubian Swell in southern Egypt and northern Sudan.