CNUGeophysics/Xception_ornithopod: Classification of large ornithopod dinosaur footprints using Xception transfer learning

<p>Source codes used for PLOS ONE article, "Classification of large ornithopod dinosaur footprints using Xception transfer learning"</p&gt

Magnetic Constraints on Off‐Axis Seamount Volcanism in the Easternmost Segment of the Australian‐Antarctic Ridge

Abstract The Australian‐Antarctic Ridge (AAR) is an intermediate‐spreading rate system located between the Southeast Indian Ridge and Macquarie Triple Junction of the Australian‐Antarctic‐Pacific plates. KR1 is the easternmost and longest AAR segment and exhibits unique axial morphology and various volcanic structures. We identified three asymmetric seamount chains positioned parallel to the seafloor spreading direction, which were indicative of prevalent off‐axis volcanism in the vicinity of segment KR1. Two‐dimensional magnetic modeling was used to predict the magnetization polarity of the seamounts, as well as to constrain their formation time and duration. The magnetic modeling revealed that the majority of the examined seamounts were formed over a period of less than ∼600 kyrs. The seamount formation primarily occurred during two distinct volcanic pulses from 0.16–1.14 to 1.58–2.69 Ma. A temporal gap of 200–650 kyrs between the formation time of the seamounts and seafloor was estimated for certain seamounts that were formed much later than their underlying seafloor and at a distance of 10–20 km from the KR1 axis. Typically, such off‐axis seamount activity is related to axial mantle convection caused by excessive magma supply near the ridge crest. Considering the scale of off‐axis volcanism and thickening lithosphere ∼20 km away from the axis with intermediate‐spreading rates, small‐scale upwelling made feasible by the fertile mantle heterogeneity is proposed as the mechanism for the seamount formations at off‐axis distances, and the geochemically enriched compositions of the seamounts support this alternative explanation

Geomorphological and Spatial Characteristics of Underwater Volcanoes in the Easternmost Australian-Antarctic Ridge

Underwater volcanoes and their linear distribution on the flanks of mid-ocean ridges are common submarine topographic structures at intermediate- and fast-spreading systems, where sufficient melt supplies are often available. Such magma sources beneath the seafloor located within a few kilometers of the corresponding ridge-axis tend to concentrate toward the axis during the upwelling process and contribute to seafloor formation. As a result, seamounts on the flanks of the ridge axis are formed at a distance from the spreading axis and distributed asymmetrically about the axis. In this study, we examined three linearly aligned seamount chains on the flanks of the KR1 ridge, which is the easternmost and longest Australian-Antarctic Ridge (AAR) segment. The AAR is an intermediate-spreading rate system located between the Southeast Indian Ridge and Macquarie Triple Junction of the Australian-Antarctic-Pacific plates. By inspecting the high-resolution shipboard multi-beam bathymetric data newly acquired in the study area, we detected 20 individual seamounts. The volcanic lineament runs parallel to the spreading direction of the KR1 segment. The geomorphologic parameters of height, basal area, volume, and summit types of the identified seamounts were individually measured. We also investigated the spatial distribution of the seamounts along the KR1 segment, which exhibits large variations in axial morphology with depth along the ridge axis. Based on the geomorphology and spatial distribution, all the KR1 seamounts can be divided into two groups: the subset seamounts of volcanic chains distributed along the KR1 segment characterized by high elevation and large volume, and the small seamounts distributed mostly on the western KR1. The differences in the volumetric magnitude of volcanic eruptions on the seafloor and the distance from the given axis between these two groups indicate the presence of magma sources with different origins

Seabed Mapping Using Shipboard Multibeam Acoustic Data for Assessing the Spatial Distribution of Ferromanganese Crusts on Seamounts in the Western Pacific

Cobalt-rich ferromanganese crusts (Fe–Mn crusts), potential economic resources for cobalt, nickel, platinum, and other rare metals, are distributed on the surface of seamounts, ridges, and plateaus. Distribution of Fe–Mn crust deposits and their geomorphological characteristics are prerequisites to selecting possible mining sites and to predicting the environmental impact of deep-sea mining activity. Here, we map the spatial distribution of Fe–Mn crust deposits on seamount summits and flanks in the Western Pacific using shipboard multibeam echo sounder (MBES) data and seafloor images from a deep-towed camera system (DCS) and evaluate the relationship between acoustic backscatter variations and the occurrence of Fe–Mn crusts. We find a positive correlation between high backscatter intensity, steep seabed slope gradients, and the occurrence of Fe–Mn crusts. However, our analysis was not effective to distinguish the spatial boundary between several seabed types that occur over small areas in mixed seabed zones, particularly where transition zones and discontinuous seabed types are present. Thus, we conclude that MBES data can be a valuable tool for constraining spatial distribution of Fe–Mn crust deposits over a large exploration area

The kinematic evolution of the Macquarie Plate: A case study for the fragmentation of oceanic lithosphere

International audienceThe tectonic evolution of the Southeast Indian Ridge (SEIR), and in particular of its easternmost edge, has not been constrained by high-resolution shipboard data and therefore the kinematic details of its behavior are uncertain. Using new shipboard magnetic data obtained by R/VIB Araon and M/V L'Astrolabe along the easternmost SEIR and available archived magnetic data, we estimated the finite rotation parameters of the Macquarie-Antarctic and Australian-Antarctic motions for eight anomalies (1o, 2, 2Ay, 2Ao, 3y, 3o, 3Ay, and 3Ao). These new finite rotations indicate that the Macquarie Plate since its creation ∼6.24 million years ago behaved as an independent and rigid plate, confirming previous estimates. The change in the Australian-Antarctic spreading direction from N-S to NW-SE appears to coincide with the formation of the Macquarie Plate at ∼6.24 Ma. Analysis of the estimated plate motions indicates that the initiation and growth stages of the Macquarie Plate resemble the kinematic evolution of other microplates and continental breakup, whereby a rapid acceleration in angular velocity took place after its initial formation, followed by a slow decay, suggesting that a decrease in the resistive strength force might have played a significant role in the kinematic evolution of the microplate. The motions of the Macquarie Plate during its growth stages may have been further enhanced by the increased subducting rates along the Hjort Trench, while the Macquarie Plate has exhibited constant growth by seafloor spreading

Extracellular Water to Total Body Water Ratio in Septic Shock Patients Receiving Protocol-Driven Resuscitation Bundle Therapy

(1) Bio-electrical impedance analysis (BIA) is a rapid, simple, and noninvasive tool for evaluating the metabolic status and for assessing volume status in critically ill patients. Little is known, however, the prognostic value of body composition analysis in septic shock patients. This study assessed the association between parameters by body composition analysis and mortality in patients with septic shock in the emergency department (ED). (2) Data were prospectively collected on adult patients with septic shock who underwent protocol-driven resuscitation bundle therapy between December 2019 and January 2021. The primary outcome was 30-day mortality. (3) The study included 261 patients, the average ratio of extracellular water (ECW) to total body water (TBW) was significantly higher in non-survivors than in survivors (0.414 vs. 0.401, p p p = 0.010), and lactate level (OR, 1.24; 95% CI, 1.12–1.37, p < 0.001) were significantly associated with 30-day mortality in patients with septic shock. (4) ECW/TBW ≥ 0.41 may be associated with 30-day mortality in patients with septic shock receiving protocol-driven resuscitation bundle therapy in the ED