The caves’ genesis from Sihla Skete area (Neamţ County, Romania)

In the modern world, new technologies in different fields of knowledge are constantly emerging every minute. In modern construction, there is a tendency for new building materials to appear. A valuable primitive building material is stone. It is also worth noting that this building material has survived to the present day and is still appreciated in the construction industry. There are deposits of valuable rock in the Rostov region. The deposits of the Meshkov stone rocks are located in the north of the Rostov region. Stone is mined for the construction of buildings, fences and other structures. It is worth emphasizing that the presented deposits of stone rocks are located on the surface of the earth, and represent a stone forest – a wonderful natural creation.

Palaeo‐formation water evolution in the Latrobe aquifer, Gippsland Basin, south‐eastern Australia continental shelf

Geodiversity in Khorat Geopark, Thailand: Approaches to geoconservation and sustainable development

Thermal maturity history and petroleum generation modelling for the Lower Cretaceous Abu Gabra Formation in the Fula Sub-basin, Muglad Basin, Sudan

The Nenana basin of interior Alaska forms a segment of the diffuse plate boundary between the Bering and North American plates and is located within a complex zone of crustal-scale strike-slip deformation that accommodates compressional stresses in response to oblique plate convergence to the south. The basin is currently the focus of new oil and gas exploration. Integration of seismic reflection and well data, fracture data, and apatite fission-track analyses with regional data improves our understanding of the tectonic development of this continental strike-slip basin. The Nenana basin formed during the Late Paleocene as a 13 km wide half-graben, affected by regional intraplate magmatism and localized crustal thinning across the Minto Fault in south-central Alaska. The basin was uplifted and exhumed along this faulted margin in the Early Eocene through to Late Oligocene in response to oblique subduction along the southern Alaska margin. This event resulted in the removal of up to 1.5 km of Late Paleocene strata from the basin. Renewed rifting and subsidence during the Early Miocene widened the basin to the west resulting in deposition of Miocene non-marine clastic rocks in reactivated and newly formed extensional half-grabens. In the Middle to Late Miocene, left lateral strike-slip faulting was superimposed on this half-graben system, with rapid subsidence beginning in the Pliocene and continuing to the present day. At present, the Nenana basin is in a zone of transtensional deformation that accommodates compressional stresses in response to oblique plate convergence and allows tectonic subsidence by oblique extension along major basin-bounding strike-slip faults.

Late Cretaceous to early Quaternary organic sedimentation in the eastern Equatorial Atlantic

Examinations of Grenville massifs in the Blue Ridge Geologic Province of Virginia and North Carolina indicate that the country rocks (∼ 1100–1450 Ma) are layered gneisses that were metamorphosed during Grenville orogenesis (∼ 1000–1100 Ma) to amphibolite to granulite facies and intruded by plutonic suites. Subsequently, the Grenville terrane was intruded by a suite of peralkaline granitic plutons (∼ 700 Ma) and progressively overlapped westward by Upper Precambrian to Cambrian sedimentary and volcanic rocks.Following deposition of Upper Precambrian and Palaeozoic rocks, the Blue Ridge Geologic Province was subjected to Taconic metamorphism (∼ 450–480 Ma) which generally increased in intensity southeastward from greenschist (chlorite grade) to upper amphibolite (sillimanite grade) facies. Large‐scale late Devonian thrusting (∼ 350 Ma) along the Fries fault system and the Brevard zone‐Yadkin fault system produced the present day distribution of juxtaposed Grenville massifs and Palaeozoic metamorphic zones in the Blue Ridge Geologic Province.Palinspastic restoration of the Taconic metamorphic zones to their pre‐late Devonian relative positions yields an ∼ 50 km displacement on the Fries fault system near the Grandfather Mountain window and and an ∼ 80 km displacement on the Smith River allochthon farther east.Restoration of the Grenville massifs to this same palinspastic base shows that Grenville metamorphic grade decreased southeastward from the deeper granulite facies (opx + gar) to the shallower granulite facies (opx ± amp) to amphibolite facies.

Metal provinces of contrasting sizes and shapes in western North America include deposits of various ages and appear to be largely unrelated to recognized major elements of crustal tectonics, as pointed out by J. A. Noble. When considered in terms of respective structural and petrologic associations, apparent ages, and implied genesis, however, the known deposits can be assigned to metallogenic provinces with a geologically systematic pattern. Five principal kinds of metal concentrations are especially useful in this connection: (1) relatively massive sulfide deposits associated with thick sections of subaqueous volcanic rocks; (2) stratiform deposits in marine sedimentary rocks; (3) stratiform deposits in terrestrial sedimentary rocks; (4) deposits in host rocks of conti ental orogens; and (5) deposits associated with major volcanic accumulations of continental affinities. The volcanogenic sulfide concentrations, which provide a long-term clue to crustal concentration processes, include Fe-Cu-Zn-Au-Ag deposits of Precambrian age that may well reflect contributions from a primitive mantle, Fe-Cu-Pb-Zn-Ag deposits of younger Precambrian and Mesozoic ages in less mafic volcanic rocks and associated eugeosynclinal strata, and post-Paleozoic Fe-Cu-Au deposits of the ophiolitic type that evidently represent mantle exhalations along zones of sea-floor spreading. Such exhalations also appear to have been responsible for accumulation of Fe, Cu, Mn, and other metals in pelagic sediments of deep ocean basins during Cenozoic time. In marked contrast are other deposits that bespeak early separation into the earth's sialic crust of metals such as Mo, W, Sn, U, and V, and continuing differentiation in this direction for Pb, Ag, and Zn. Unlike those of more direct mantle derivation, these deposits evidently have required recycling of metals through various combinations of sedimentation, crustal melting, vapor transport, and new mantle contributions to explain their levels of concentration. Thus current models of metallization along zones of continental rifting, sea-floor spreading, and subduction of oceanic crust can account directly for the development of some important deposits, but they must include at least partly related processes of concentration and reconcentration within the continental crust to explain all of the recognized metallogenic provinces. The copper province of Arizona is perhaps the best example of such complicated interplay over a very long period of geologic time. End_of_Article - Last_Page 1442------------

Sulfide minerals in Mesozoic replacement, skarn, porphyry, and vein deposits in lower Paleozoic rocks in central and eastern Nevada have sulfur isotope compositions (10‰ ≤ δ 34 S 206 Pb/ 204 Pb ∼ 19) that are elevated relative to the range of S and Pb isotope compositions in eastern Great Basin metal deposits. The S and Pb isotope compositions of central and eastern Nevada Mesozoic metal deposits (e.g., Eureka) are similar to the S and Pb isotope compositions of pyrite disseminated in the thick (is less than or equal to 8 km) terrigenous detrital succession (TDS) of siliciclastic rocks of Late Proterozoic–Early Cambrian age subjacent to the deposits. TDS rocks are, therefore, a possible source for most if not all S and Pb in these deposits. To the south and east in southern Nevada, southeastern California, and western Utah, progressively thinner TDS rocks correlate with lower δ 34 S values ( 206 Pb/ 204 Pb ratios ( S and Pb isotope compositions of sulfide minerals in metal deposits that are temporally related to middle Tertiary granitic intrusions also vary geographically and are generally lower than isotope compositions of Mesozoic metal deposits, regardless of Paleozoic host-rock age. Compared to the Mesozoic deposits, middle Tertiary deposits in central and eastern Nevada apparently derived significant, but mostly smaller, amounts of S and Pb from TDS rocks and/or Paleozoic rocks. Tertiary metal deposits in western Utah may have obtained nearly all their S and Pb from older Precambrian crystalline rocks or from magmas and virtually none from TDS and Paleozoic rocks. Semiquantification of source-rock contributions of S and Pb to metal deposits is based on average S and Pb isotope compositions of possible source rocks and simple mixing calculations. Possible source rocks are somewhat isotopically inhomogeneous, but their S and Pb isotope compositional ranges largely bracket the S and Pb isotope compositions of metal deposits in the eastern Great Basin, thus facilitating determination of end-member contributions. Geologic factors that cause isotope inhomogeneity in both source rocks and metal deposits include different source-rock provenances, particularly for Pb isotopes, isotope mixing and fractionation by unrecognized hydrothermal processes, metamorphism, and tectonism that has juxtaposed potential source rocks of differing ages and isotope compositions. TDS pyrite formed from processes that produced S with high δ 34 S values—including diagenesis involving seawater sulfate and, at higher temperatures and greater depths, thermochemical sulfate reduction. Radiogenic Pb in TDS pyrite was derived from leaching of quartzofeldspathic sedimentary rocks. Granitic melts acquired S and Pb, and possibly other ore-forming components, by bulk assimilation of TDS and/or Paleozoic sedimentary rocks, Proterozoic crystalline rocks, and possibly older Precambrian rocks; by volatilization of disseminated pyrite in source rocks during ascent; and by hydrothermal circulation near the sites of ore deposition. The high density of eastern Great Basin metal deposits and the sources of S and Pb for these deposits appear to be a function not only of the large number of granitic intrusions, but also of intrusion age and the thickness and type of Precambrian crust. S and Pb isotope compositions in eastern Great Basin metal deposits support a proposed origin for Jurassic, Cretaceous, and Tertiary intrusions that involves generation of magmas at different crustal levels and variable amounts of magmatic contamination by Precambrian rocks.

The western edge of Laurentia in the Lower Paleozoic is a passive margin similar to passive margins found throughout time around the world. The northwestern part of the margin transitions from carbonate platform to basin (Selwyn basin) to carbonate platform (Cassiar/McEvoy platform) from northeast to southwest. In the Late Devonian and Early Mississippian, the Laurentian margin underwent a period of extension that disrupted passive margin sedimentation and resulted in deposition of primarily quartz-rich clastic rocks. New mapping in central Yukon in the Selwyn basin has delineated a major structure, the Twopete fault, which is a reactivated structure that may be as old as the Cambro-Ordovician. The Twopete fault separates two distinct rock panels, Devonian to Triassic sedimentary strata in its footwall against Cambrian to Ordovician, variably metamorphosed sedimentary and volcanic rocks in its hangingwall. A succession of Ordovician siliclastic rocks deposited in a shallow water environment are locally exposed in the hangingwall of the fault. We propose a margin parallel, crustal scale structure active in the Cambro-Ordovician and reactivated periodically throughout the Lower Paleozoic, to explain the geological pattern along the Twopete fault. For example, the eruption of Ordovician volcanic rocks that occur in the hangingwall. Shallow water siliclastic rocks in the Twopete hangingwall may represent the basement to a carbonate platform that developed during the Silurian and Devonian southwest of the Twopete fault equivalent to the Cassiar/McEvoy platform exposed in Yukon to the southeast. Detailed mapping along the Twopete fault provides evidence that it was a syn-sedimentary fault in the Late Devonian that controlled deposition of Upper Devonian sedimentary rocks and emplacement of coeval intrusive rocks. Lastly, the concentration and linear nature of Cretaceous intrusions near the Twopete fault suggest pre-existing structural features have influenced their emplacement. The Twopete fault is a significant structure in central Yukon that likely influenced the eruption and deposition of Cambro-Ordovician, Late Devonian and Cretaceous igneous rocks, the formation of a Silurian to Devonian carbonate platform and deposition of Upper Devonian clastic rocks.

Fossils are the remains organisms from earlier geological periods preserved in sedimentary rock. The global fossil record documents and characterizes the evidence about organisms that existed at different times and places during the Earth’s history. One of the major directions in computational analysis of such data is to reconstruct environmental conditions and track climate changes over millions of years. Distribution of fossil animals in space and time make informative features for such modeling, yet concept drift presents one of the main computational challenges. As species continuously go extinct and new species originate, animal communities today are different from the communities of the past, and the communities at different times in the past are different from each other. The fossil record is continuously increasing as new fossils and localities are being discovered, but it is not possible to observe or measure their environmental contexts directly, because the time is gone. Labeled data linking organisms to climate is available only for the present day, where climatic conditions can be measured. The approach is to train models on the present day and use them to predict climatic conditions over the past. But since species representation is continuously changing, transfer learning approaches are needed to make models applicable and climate estimates to be comparable across geological times. Here we discuss predictive modeling settings for such paleoclimate reconstruction from the fossil record. We compare and experimentally analyze three baseline approaches for predictive paleoclimate reconstruction: (1) averaging over habitats of species, (2) using presence-absence of species as features, and (3) using functional characteristics of species communities as features. Our experiments on the present day African data and a case study on the fossil data from the Turkana Basin over the last 7 million of years suggest that presence-absence approaches are the most accurate over short time horizons, while species community approaches, also known as ecometrics, are the most informative over longer time horizons when, due to ongoing evolution, taxonomic relations between the present day and fossil species become more and more uncertain.

Multiple phases of North African humidity recorded in lacustrine sediments from the Fazzan Basin, Libyan Sahara

Geochemical exploration models for sedimentary uranium deposits

Water, through its unique and extreme properties, is the fundamental fluid genetically relating all mineral deposits in sedimentary rocks. Economically important mineral deposits in sedimentary rocks which are the result of natural water-rock interaction include petroleum and Mississippi-type lead-zinc deposits. Understanding of the origin of these deposits through water-rock interaction requires knowledge of the relations between hydrochemistry and hydrodynamics. The recovery of some of these mineral deposits involves man-imposed water-rock interactions, for example, during water flooding of petroleum reservoirs, in-situ steam injection into oil sand deposits and underground coal gasification. These man-imposed water-rock interactions may result in subsurface reactions w ich can reduce permeability, produce toxic or deleterious substances which require removal before reuse of the produced water, contaminate local potable groundwater, or cause problems in waste injection wells because of subsequent water-rock reactions. Although we understand some of the principles involved, it is clear that considerably more thought and additional research effort needs to be directed to these and other economic aspects of water-rock interaction.

Water, through its unique and extreme properties, is the fundamental fluid genetically relating all mineral deposits in sedimentary rocks. Economically important mineral deposits in sedimentary rocks which are the result of natural water-rock interaction include petroleum and Mississippi-type lead-zinc deposits. Understanding of the origin of these deposits through water-rock interaction requires knowledge of the relations between hydrochemistry and hydrodynamics. The recovery of some of these mineral deposits involves man-imposed water-rock interactions, for example, during water flooding of petroleum reservoirs, in-situ steam injection into oil sand deposits and underground coal gasification. These man-imposed water-rock interactions may result in subsurface reactions w ich can reduce permeability, produce toxic or deleterious substances which require removal before reuse of the produced water, contaminate local potable groundwater, or cause problems in waste injection wells because of subsequent water-rock reactions. Although we understand some of the principles involved, it is clear that considerably more thought and additional research effort needs to be directed to these and other economic aspects of water-rock interaction.