Recent Advances in Geological Oceanography II

1. Introduction

Marine geology is a well-known [1,2] and still-developing field of research that deals with geological bodies and processes below the sea level and sometimes refers to ancient marine environments. Moreover, it is evident that the geological peculiarities of seas and oceans can influence their physical and biological states and overall dynamics [3]. Such influences are partly moderated by the geological-scale activities of humans. It is very reasonable to talk about geological oceanography as a more general discipline focusing on both elementary and highly complex phenomena, including the interactions of geological and non-geological objects and processes.

Significant achievements have already been made in the field of geological oceanography in the 2020s. Huang et al. [4] examined the diversity of sedimentation rates across the World Ocean in the Quaternary and registered several intriguing patterns. Martin Erin et al. [5] reconsidered ocean evolution via a general tectonic concept known as Wilson’s cycle. Pohl et al. [6] explained how major plate tectonic processes affected oxygen concentrations in seawater during the Phanerozoic. According to Klausen et al. [7], it was sea-level changes that drove the early evolution of the dinosaurs. Gao et al. [8] established that the construction of artificial reefs is related to the deep involvement of plastics in marine sedimentation. These examples demonstrate the outstanding width of the agenda of geological oceanography, as well as the high complexity of the problems it seeks to solve.

Despite numerous achievements, much is yet to be understood about the geological context of our seas and oceans. For instance, it is very possible that the diversity of models describing the birth and tectonic evolution of our oceans under different conditions is incompletely understood [9,10,11]. Peculiarities of depositional and diagenetic processes in ancient seas can be documented only via multiple studies in starkly different regions and geological time slices [12,13]. Our knowledge of geophysical processes, including those related to submarine seismicity and hydrothermal growth, must be further enhanced [14,15,16]. Such phenomena as pre-Quaternary tsunamis [17,18] and ocean palaeoproductivity changes [19,20,21,22] are known, but our knowledge is still fragmentary. Geochemical changes on the shores and at bottom of the seas and oceans related to increasing anthropogenic pressure and the input of new, non-natural materials (such as plastics) require monitoring, and the our information on them requires regular updating [23,24]. Finally, the geological resources of on our ocean floors remain a subject demanding further exploration [25,26,27,28]. These noted gaps in our knowledge underpin the urgency of research in the field of geological oceanography, as well as the breadth of the relevant topics and directions.

The present Special Issue, entitled “Recent Advances in Geological Oceanography II”, aims to contribute to the international growth of the field of geological oceanography. It contains a collection of research and review articles by specialists from different countries and regions, address a number of the principal problems remaining in this field. In particular, they contribute to filling in some of the knowledge gaps mentioned above, from the initial oceanization to seafloor hydrothermal activity and from very ancient tsunamis to plastic cycling in modern seashore environments.

2. Published Papers

Liu et al. (Contribution 1) investigated and addressed the increasing complexity of the depositional conditions and their effects on organic matter accumulation and preservation derived from a series of Lower Paleozoic shale samples at the northeastern margin of the Yangtze platform in south China. The analyses incorporate TOC content, mineral composition, and major, trace, and rare earth elements into the investigation. This enables the analysis of how different factors such as paleoredox state, paleoproductivity, preservation, paleoclimate, and terrestrial influx intensity impact organic matter enrichment in this setting.

A comprehensive review by Mikhailenko and Ruban (Contribution 2) provides valuable insights into the global geographical distribution of plastics and five associated heavy metals (cadmium, chromium, mercury, nickel, and zinc) on sea beaches, highlighting both real and potential risks to the environment. The results indicate that the geographical extent of our knowledge of Hg-bearing plastics is highly limited. Overall, the findings of this literary study widen the focus on Anthropocene marine geochemistry.

Sang et al. (Contribution 3) present an analytical model for the punctiform breakup and initial oceanization of the central Red Sea rift. The integrated model incorporates new reflection seismic profiles and gravity modeling results and focuses on the density structure, tectonic evolution, breakup mechanism, and future evolution of this continuously spreading setting.

Yutsis et al. (Contribution 4) provide new insights into the seamount structure of the northern part of the Ninetyeast Ridge in the Indian Ocean. The investigative geophysical methods used in this study include bathymetric, seismostratigraphic, and magnetic data. By integrating these aspects, the study provides a comprehensive approach, enabling comparisons with similar settings in a global context.

Wang et al. (Contribution 5) represent a numerical simulation-based analysis of the seafloor hydrothermal plumes in Carlsberg Ridge in the northwestern Indian Ocean. The proposed model is based on the topography of the region and long-term current monitoring data and allows for the reconstruction of the present hydrothermal plume in terms of its structure, velocity field, and temperature field. The findings of this study provide useful information for tracing the hydrothermal vents, prospecting the submarine polymetallic sulfide resources, and designing long-term observation networks, and provide a foundation for future studies on element cycling and the energy budget.

Qamar et al. (Contribution 6) offer an in-depth exploration of the sedimentology, diagenesis, and sequence stratigraphy of the middle Jurassic carbonate deposits of north Pakistan, employing a multi-proxy approach which involves field observations, paleontological analysis, and sedimentological microfacies characterization. This study provides valuable insights into the complex diagenetic history and sequence stratigraphy of the Middle Jurassic Samana Suk Formation in the Hazara basin, shedding light on the depositional stages and highlighting the reservoir characteristics of these shallow-to-marginal marine carbonates for possible hydrocarbon exploration in the future.

Gao et al. (Contribution 7) examine the provenance of the Lower Jurassic Badaowan and Sangonghe Formations in the Junggar Basin and the constraint it poses on the Karamaili Ocean. The interpretation of the sandstone-derived petrological and geochronological results allow for a better understanding of the evolution of the Paleo-Karamaili orogenic belt as part of the Paleo-Asian Ocean, supported by three distinct evolutionary stages.

Through a systematic review, Ruban and Yashalova (Contribution 8) present a synthesis of the available information related to Ordovician tsunamis. In particular, the authors describe a summary of potential hypotheses based on 24 events in different localities around the world, with further implications for geoheritage resources. In this regard, the outcomes of this study contribute to a better awareness of the world’s geoheritage resources during the Phanerozoic period, and they also, through comparisons with similar events throughout the Cenozoic era, form a basis for further study.

Shi et al. (Contribution 9) represent a new biomonitoring approach with which to determine the biotoxic effects of Ag nanoparticles on coasts. The experiment was conducted on Skeletonema costatum, the most typical phytoplankton species in coastal settings. The results of this environmental study shed light on the biological toxicity of nanometals and their possible toxicity mechanism.

The study of Krylov et al. (Contribution 10) is devoted to the features of seismological observations in the Arctic seas, which are complicated by harsh climatic conditions, the presence of ice cover, stamukhi and icebergs, and limited navigation. This study could be considered a reference study, referring, in great detail, to the features and difficulties of seismological operation systems in such “noisy” environments.

Vakalas and Zananiri (Contribution 11) present a sedimentological study of the North Aegean Sea (Greece) based on their investigation of 323 surficial marine sediments. The sediment transport patterns were analyzed based on the grain size parameters (mean, sorting, and skewness). The dominant factors affecting sediment transport are river discharge and longshore drift near the shoreline, while open sea water circulation controls sediment distribution patterns at the open shelf. Moreover, the strong heterogeneity of the sediment textural parameters across the study area suggests that seafloor sediments are further reworked in areas where water masses are highly energetic.

3. Perspectives

The articles in this Special Issue fill many particular gaps in our knowledge of the geological context of seas and oceans. Taken together, they amply demonstrate that the field of geological oceanography is wide, complex, and highly diverse. This is an arena ripe for inter- and multidisciplinary research where “pure” geologists and oceanographers can cooperate with geophysicists, geochemists, environmental scientists, marine geologists, sedimentologists, and geomorphologists. In this field, classical and advanced research projects can co-exist (and benefit one another), and field-based, modeling, and conceptual studies are also possible. Indeed, one single Special Issue cannot (and should not) represent the entire research field (especially one so vast as geological oceanography), but it can try to demonstrate its central ideas and potential.

In solving some important questions, the contributors to the present Special Issue raise new ones, including (but not limited to) the following:

(1)

Did the Early Paleozoic organic matter enrichment in the Yangtze Platform reflect the actions of any planetary-scale mechanisms?

(2)

What is the true diversity of seamount structures in the World Ocean?

(3)

Do the Middle Jurassic marine carbonates of North Pakistan record any global-scale events?

(4)

Were there differences and irregularities in the preservation of tsunami records in the time slices of the Phanerozoic?

(5)

Is it possible to develop a single protocol for seismological investigations at high latitudes?

These are specific questions for specialized projects. More generally, this Special Issue highlights two important perspectives for future research. The first perspective is linked to identifying and subsequently examining those features that mark the diversity of the geological environments of our seas and oceans. The second perspective refers to the geological (and geological-scale) activities of humans in marine environments that alter, disrupt, or modify natural geological cycles and trends.