Absolute plate motion, mantle flow, and volcanism at the boundary between the Pacific and Indian Ocean mantle domains since 90 Ma

<p>Detailed knowledge of the seismic structure, fabric, and dynamics that surround the oceanic LAB continue to be refined through offshore seismic studies. Previous high-resolution studies in the Pacific basin far from plate boundaries show asthenospheric fabric that aligns neither with the lithospheric fabric (the paleo-spreading direction) nor with absolute plate motion, but rather in between. Here we present preliminary results from the Blanco Transform and Cascadia Initiative experiments, investigating the structure of the Juan de Fuca and Pacific plates on either side of the Blanco Transform. We measure ambient-noise and teleseismic Rayleigh-wave phase velocities, and solve for the period-dependent azimuthal anisotropy on either side of the transform. We will contextualize and interpret the fabrics based on mantle flow inferred from these previous Pacific basin studies.&#160;</p>

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Kinematics and dynamics of the East Pacific Rise linked to a stable, deep-mantle upwelling

Science Advances ◽

10.1126/sciadv.1601107 ◽

2016 ◽

Vol 2 (12) ◽

pp. e1601107 ◽

Cited By ~ 11

Author(s):

David B. Rowley ◽

Alessandro M. Forte ◽

Christopher J. Rowan ◽

Petar Glišović ◽

Robert Moucha ◽

...

Keyword(s):

East Pacific Rise ◽

Oceanic Lithosphere ◽

Plate Motion ◽

Mantle Flow ◽

Plate Boundaries ◽

Tectonic Plates ◽

Ocean Ridges ◽

East Pacific ◽

The Pacific ◽

Negative Buoyancy

Earth’s tectonic plates are generally considered to be driven largely by negative buoyancy associated with subduction of oceanic lithosphere. In this context, mid-ocean ridges (MORs) are passive plate boundaries whose divergence accommodates flow driven by subduction of oceanic slabs at trenches. We show that over the past 80 million years (My), the East Pacific Rise (EPR), Earth’s dominant MOR, has been characterized by limited ridge-perpendicular migration and persistent, asymmetric ridge accretion that are anomalous relative to other MORs. We reconstruct the subduction-related buoyancy fluxes of plates on either side of the EPR. The general expectation is that greater slab pull should correlate with faster plate motion and faster spreading at the EPR. Moreover, asymmetry in slab pull on either side of the EPR should correlate with either ridge migration or enhanced plate velocity in the direction of greater slab pull. Based on our analysis, none of the expected correlations are evident. This implies that other forces significantly contribute to EPR behavior. We explain these observations using mantle flow calculations based on globally integrated buoyancy distributions that require core-mantle boundary heat flux of up to 20 TW. The time-dependent mantle flow predictions yield a long-lived deep-seated upwelling that has its highest radial velocity under the EPR and is inferred to control its observed kinematics. The mantle-wide upwelling beneath the EPR drives horizontal components of asthenospheric flows beneath the plates that are similarly asymmetric but faster than the overlying surface plates, thereby contributing to plate motions through viscous tractions in the Pacific region.

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Research Gap Analysis of Remote Sensing Application in Fisheries: Prospects for Achieving the Sustainable Development Goals

Remote Sensing ◽

10.3390/rs13051013 ◽

2021 ◽

Vol 13 (5) ◽

pp. 1013

Author(s):

Kuo-Wei Yen ◽

Chia-Hsiang Chen

Keyword(s):

Sustainable Development ◽

Indian Ocean ◽

Atlantic Ocean ◽

The Sustainable Development ◽

The North ◽

The Pacific ◽

Development Goals ◽

The Indian Ocean ◽

The Pacific Ocean ◽

Research Hotspots

Remote sensing (RS) technology, which can facilitate the sustainable management and development of fisheries, is easily accessible and exhibits high performance. It only requires the collection of sufficient information, establishment of databases and input of human and capital resources for analysis. However, many countries are unable to effectively ensure the sustainable development of marine fisheries due to technological limitations. The main challenge is the gap in the conditions for sustainable development between developed and developing countries. Therefore, this study applied the Web of Science database and geographic information systems to analyze the gaps in fisheries science in various countries over the past 10 years. Most studies have been conducted in the offshore marine areas of the northeastern United States of America. In addition, all research hotspots were located in the Northern Hemisphere, indicating a lack of relevant studies from the Southern Hemisphere. This study also found that research hotspots of satellite RS applications in fisheries were mainly conducted in (1) the northeastern sea area in the United States, (2) the high seas area of the North Atlantic Ocean, (3) the surrounding sea areas of France, Spain and Portugal, (4) the surrounding areas of the Indian Ocean and (5) the East China Sea, Yellow Sea and Bohai Bay sea areas to the north of Taiwan. A comparison of publications examining the three major oceans indicated that the Atlantic Ocean was the most extensively studied in terms of RS applications in fisheries, followed by the Indian Ocean, while the Pacific Ocean was less studied than the aforementioned two regions. In addition, all research hotspots were located in the Northern Hemisphere, indicating a lack of relevant studies from the Southern Hemisphere. The Atlantic Ocean and the Indian Ocean have been the subjects of many local in-depth studies; in the Pacific Ocean, the coastal areas have been abundantly investigated, while offshore local areas have only been sporadically addressed. Collaboration and partnership constitute an efficient approach for transferring skills and technology across countries. For the achievement of the sustainable development goals (SDGs) by 2030, research networks can be expanded to mitigate the research gaps and improve the sustainability of marine fisheries resources.

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Sources of Tropical Subseasonal Skill in the CFSv2

Monthly Weather Review ◽

10.1175/mwr-d-19-0289.1 ◽

2020 ◽

Vol 148 (4) ◽

pp. 1553-1565 ◽

Cited By ~ 1

Author(s):

Carl J. Schreck ◽

Matthew A. Janiga ◽

Stephen Baxter

Keyword(s):

Indian Ocean ◽

Low Frequency ◽

Equatorial Pacific ◽

Convectively Coupled Equatorial Waves ◽

Subseasonal Variability ◽

The Pacific ◽

Fourier Filtering ◽

The Indian Ocean ◽

Rainfall Anomalies ◽

Combined Data

Abstract This study applies Fourier filtering to a combination of rainfall estimates from TRMM and forecasts from the CFSv2. The combined data are filtered for low-frequency (LF, ≥120 days) variability, the MJO, and convectively coupled equatorial waves. The filtering provides insight into the sources of skill for the CFSv2. The LF filter, which encapsulates persistent anomalies generally corresponding with SSTs, has the largest contribution to forecast skill beyond week 2. Variability within the equatorial Pacific is dominated by its response to ENSO, such that both the unfiltered and the LF-filtered forecasts are skillful over the Pacific through the entire 45-day CFSv2 forecast. In fact, the LF forecasts in that region are more skillful than the unfiltered forecasts or any combination of the filters. Verifying filtered against unfiltered observations shows that subseasonal variability has very little opportunity to contribute to skill over the equatorial Pacific. Any subseasonal variability produced by the model is actually detracting from the skill there. The MJO primarily contributes to CFSv2 skill over the Indian Ocean, particularly during March–May and MJO phases 2–5. However, the model misses opportunities for the MJO to contribute to skill in other regions. Convectively coupled equatorial Rossby waves contribute to skill over the Indian Ocean during December–February and the Atlantic Ocean during September–November. Convectively coupled Kelvin waves show limited potential skill for predicting weekly averaged rainfall anomalies since they explain a relatively small percent of the observed variability.

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A subduction influence on ocean ridge basalts outside the Pacific subduction shield

Nature Communications ◽

10.1038/s41467-021-25027-2 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

A. Y. Yang ◽

C. H. Langmuir ◽

Y. Cai ◽

P. Michael ◽

S. L. Goldstein ◽

...

Keyword(s):

Upper Mantle ◽

The Arctic ◽

Mantle Flow ◽

Mantle Heterogeneity ◽

Gakkel Ridge ◽

The Pacific ◽

Mid Ocean Ridge ◽

The Pacific Ocean ◽

Back Arc ◽

Ocean Ridge

AbstractThe plate tectonic cycle produces chemically distinct mid-ocean ridge basalts and arc volcanics, with the latter enriched in elements such as Ba, Rb, Th, Sr and Pb and depleted in Nb owing to the water-rich flux from the subducted slab. Basalts from back-arc basins, with intermediate compositions, show that such a slab flux can be transported behind the volcanic front of the arc and incorporated into mantle flow. Hence it is puzzling why melts of subduction-modified mantle have rarely been recognized in mid-ocean ridge basalts. Here we report the first mid-ocean ridge basalt samples with distinct arc signatures, akin to back-arc basin basalts, from the Arctic Gakkel Ridge. A new high precision dataset for 576 Gakkel samples suggests a pervasive subduction influence in this region. This influence can also be identified in Atlantic and Indian mid-ocean ridge basalts but is nearly absent in Pacific mid-ocean ridge basalts. Such a hemispheric-scale upper mantle heterogeneity reflects subduction modification of the asthenospheric mantle which is incorporated into mantle flow, and whose geographical distribution is controlled dominantly by a “subduction shield” that has surrounded the Pacific Ocean for 180 Myr. Simple modeling suggests that a slab flux equivalent to ~13% of the output at arcs is incorporated into the convecting upper mantle.

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The Dimensions of the US-China Trade War

Open Political Science ◽

10.1515/openps-2020-0004 ◽

2020 ◽

Vol 3 (1) ◽

pp. 47-55

Author(s):

Mohamad Zreik

Keyword(s):

United States ◽

Indian Ocean ◽

Free Trade ◽

The United States ◽

Bilateral Agreements ◽

China Trade ◽

The Pacific ◽

The Us ◽

The Indian Ocean ◽

Trade War

AbstractThe Chinese Ministry of Commerce issued a statement Friday morning, July 6, 2018, confirming the outbreak of a trade war between the United States and China. The statement came after the United States imposed tariffs on many Chinese goods, in violation of international and bilateral agreements, and the destruction of the concept of free trade which the United States calls for following it. It is a war of opposite directions, especially the contradiction between the new Trump policy and the Chinese approach. The proof is what US Defense Secretary James Matisse announced in Singapore in early June 2018 of “the full strategy of the new United States, in the Indian Ocean and the Pacific,” where China was the “sole enemy of the United States” in China’s geostrategic region. Intentions have become publicized, and trade war between the two economic giants is turning into a reality. This paper will give an overview of the US-China scenario of trade war, then a focused analysis on the Trump’s administration economic decision regarding China, and the consequences of this decision.

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Vallicula multiformis Rankin, 1956 (Ctenophora, Platyctenida): first record from the Indian Ocean

Check List ◽

10.15560/11.1.1544 ◽

2015 ◽

Vol 11 (1) ◽

pp. 1544 ◽

Cited By ~ 3

Author(s):

Amruta Prasade ◽

Deepak Apte ◽

Purushottam Kale ◽

Otto M.P. Oliveira

Keyword(s):

Indian Ocean ◽

Geographic Distribution ◽

West Coast ◽

Arabian Sea ◽

First Record ◽

West Coast Of India ◽

The Pacific ◽

The Indian Ocean ◽

First Time

The benthic ctenophore Vallicula multiformis Rankin, 1956 is recorded for the first time in the Arabian Sea, from the Gulf of Kutch, west coast of India in March 2013. This occurrence represents a remarkable extension of its geographic distribution that until now included only known the Pacific and Atlantic oceans.

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Analysis of the difference in depths and variation in slope steepness of the Sunda Trench, Indonesia, east Indian Ocean

Revista de Geomorfologie ◽

10.21094/rg.2020.096 ◽

2020 ◽

Vol 22 (1) ◽

pp. 21-41

Author(s):

Polina Lemenkova

Keyword(s):

Indian Ocean ◽

Geometric Shape ◽

Shelf Area ◽

High Resolution Data ◽

East Indian ◽

Slope Steepness ◽

Indonesian Archipelago ◽

Geological Processes ◽

The Pacific ◽

The Difference

The paper discusses geomorphology of the Sunda Trench, an oceanic trench located in eastern Indian Ocean along the Sumatra and Java Islands of the Indonesian archipelago. In particular, it analysis the difference in depths and variation in slope steepness between the two segments of the trench: the southern Java transect (coordinates 108.8°E 10.10°S to 113.0°E 10.75°S) and the northern Sumatra transect (97.5°E 1.1°S to 101.0°E 5.5°S). The thematic maps and geomorphological modelling were plotted using Generic Mapping Tools (GMT). The materials include high-resolution data on topography, geology and geophysics: GEBCO 15 arc-minute resolution grid, EGM2008 2.5 minute Earth Gravitation Model of 2008, GlobSed global 5‐arc‐minute total sediment thickness and vector geological datasets. In addition to the GEBCO-based bathymetric data, geological, topographic and geophysical maps, the results include enlarged transects for the Java and Sumatra segments, their slope gradients and cross-section profiles, derived from the bathymetric GEBCO dataset. The geomorphology framework of the Sunda Trench is largely controlled by the subduction of the Australian plate underneath the Sunda microplate. The geological processes take place in basin of the Indian Ocean at different stages of its evolution and influence the nature of the submarine geomorphology and geometric shape of the trench. Sunda Trench is seismically active part of the Pacific Ring of Fire. A large number of the catastrophic earthquakes are recorded around the trench. The histograms shows variation in depths along the segments of the Sumatra and Java. The Java segment has a bell-shaped data distribution in contrast to the Sumatra with bimodal pattern. The Java segment has the most repetitive depths at -2,500 to -5,200 m. The Sumatra transect has two peaks: 1) a classic bell-shaped peak at depths -4,500 m to -5,500 m; 2) shelf area with a peak from 0 to -1,750 m. The data at middle depths (-1,750 to -4,500 m) have a frequency <300 samples. The most frequent bathymetry for the Sumatra segment corresponds to the -4,750 m to -5,000 m (2,151 samples). Comparing to the Sumatra segment, the Java segment is deeper. For the depths >-6,000 m, there are only 138 samples for the Sumatra while 547 samples for Java. Furthermore, Java segment has more symmetrical geometric shape while Sumatra segment is asymmetric, one-sided. The Sumatra segment has a steepness of 57.86° on its eastern side (facing Sumatra Island) and a contrasting 14.58° on the western part. The Java segment has a steepness of 64.34° on its northern side (facing Java Island) and 24.95° on the southern part (facing Indian Ocean). The paper contributes to the studies of the submarine geomorphology in Indonesia.

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Morphological and genetic evaluation of the thumbprint emperor, Lethrinus harak (Forsskål, 1775) in the Pacific and Indian Oceans

F1000Research ◽

10.12688/f1000research.23740.2 ◽

2021 ◽

Vol 9 ◽

pp. 915

Author(s):

Muhammad Afrisal ◽

Yukio Iwatsuki ◽

Andi Iqbal Burhanuddin

Keyword(s):

Pacific Ocean ◽

Indian Ocean ◽

Genetic Distance ◽

Marine Biology ◽

Sequence Data ◽

Statistical Tests ◽

Accurate Determination ◽

Morphometric Character ◽

Morphometric Characters ◽

The Pacific

Background: The Lethrinidae (emperors) include many important food fish species. Accurate determination of species and stocks is important for fisheries management. The taxonomy of the genus Lethrinus is problematic, for example with regards to the identification of the thumbprint emperor Lethrinus harak. Little research has been done on L. harak diversity in the Pacific and Indian Oceans. This study aimed to evaluate the morphometric and genetic characters of the thumbprint emperor, L. harak (Forsskål, 1775) in the Pacific and Indian Oceans. Methods: This research was conducted in the Marine Biology Laboratory, Faculty of Marine Science and Fisheries, Hasanuddin University, and Division of Fisheries Science, University of Miyazaki. Morphometric character measurements were based on holotype character data, while genetic analysis was performed on cytochrome oxidase subunit I (COI) sequence data. Morphometric data were analysed using principal component analysis (PCA) statistical tests in MINITAB, and genetic data were analysed in MEGA 6. Results: Statistical test results based on morphometric characters revealed groupings largely representative of the Indian and Pacific Oceans. The Seychelles was separated from other Indian Ocean sites and Australian populations were closer to the Pacific than the Indian Ocean group. The genetic distance between the groups was in the low category (0.000 - 0.042). The phylogenetic topology reconstruction accorded well with the morphometric character analysis, with two main L. harak clades representing Indian and Pacific Ocean, and Australia in the Pacific Ocean clade. Conclusions: These results indicate that the morphological character size of L. harak from Makassar and the holotype from Saudi Arabia have changed. Genetic distance and phylogeny reconstruction are closely related to low genetic distance.

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