Blog Profile / GeoScienceWorld


URL :http://geoscienceworld.org/
Filed Under:Academics / Geology
Posts on Regator:213
Posts / Week:6.5
Archived Since:September 5, 2016

Blog Post Archive

A Laurentian record of the earliest fossil eukaryotes

The oldest evidence of eukaryotes in the fossil record comes from a recurrent assemblage of morphologically differentiated late Paleoproterozoic to early Mesoproterozoic microfossils. Although widely distributed, the principal constituents of this Tappania - Dictyosphaera - Valeria assemblage have not hitherto been recognized on Laurentia. Show More Summary

The basement revealed: Tectonic insight from a digital elevation model of the Great Unconformity, USA cratonic platform

Across much of North America, the contact between Precambrian basement and Paleozoic strata is the Great Unconformity, a surface that represents a >0.4 b.y.-long hiatus. A digital elevation model (DEM) of this surface visually highlights regional-scale variability in the character of basement topography across the United States cratonic platform. Show More Summary

Evidence from paleosols for low to moderate elevation of the India-Asia suture zone during mid-Cenozoic time

The post-collisional uplift history of the India-Asia suture zone in southern Tibet is important for understanding the geodynamic conditions of the India-Asia collision and how it may have modified regional and global climate. Here we...Show More Summary

Widespread persistence of expanded East Antarctic glaciers in the southwest Ross Sea during the last deglaciation

It has been suggested that the grounding line of the Last Glacial Maximum (LGM) ice sheet in the Ross Sea, Antarctica, receded in an approximately north-to-south pattern during the Holocene. An implication of this hypothesis is thatShow More Summary

Zircon Hf-O isotope evidence for recycled oceanic and continental crust in the sources of alkaline rocks

Post-orogenic and intraplate extensional alkaline rocks are believed to have formed by partial melting of metasomatized ultramafic rocks in the subcontinental lithospheric mantle. Their variable incompatible element abundances and radiogenic...Show More Summary

Tracing weathering regimes using the lithium isotope composition of detrital sediments

Lithium (Li) isotopes are a promising tracer of chemical weathering processes for both modern and ancient times. In order to improve the use of Li isotopes in the sedimentary record, here we calibrate the relationship between weathering intensity and detrital Li isotope composition ( 7 Li) using the fine fraction of modern large river sediments. Show More Summary

Seismogenic deformation between the Sierran microplate and Oregon Coast block, California, USA

The Sierran microplate is a northwest-translating block entrained in distributed motion east of the Pacific plate. To the north, the Oregon coast block (OCB) moves northward within the hanging wall of the Cascadia subduction zone, above the obliquely converging Juan de Fuca plate. Show More Summary

Anomalous sulfur isotopes trace volatile pathways in magmatic arcs

The cycle of sulfur, an important volatile in Earth’s crust, is the driver of many significant processes such as biological evolution, climate change, and the formation of ore deposits. This study investigates the ancient cycle of volatiles...Show More Summary

Gypsum gravel devils in Chile: Movement of largest natural grains by wind?

Whirlwinds, dry convective helical vortices, move large gypsum crystals in the Andes Mountains of northern Chile. The crystals are entrained from a saline pan surface, where they grew in shallow surface brines. They are transported as much as 5 km and deposited in large dune-like mounds. Show More Summary

Tectonic melange records the Silurian-Devonian subduction-metamorphic process of the southern Dunhuang terrane, southernmost Central Asian Orogenic Belt

The Hongliuxia tectonic mélange of the southern Dunhuang terrane, northwestern China, southernmost Central Asian Orogenic Belt (CAOB), consists of eclogite, mafic granulite, and amphibolite as puddingstones within a matrix of metapelitic gneiss and marble; these rocks are interpreted to be part of an ancient subduction zone setting. Show More Summary

Structure and dynamics of surface uplift induced by incremental sill emplacement

Shallow-level sill emplacement can uplift Earth’s surface via forced folding, providing insight into the location and size of potential volcanic eruptions. Linking the structure and dynamics of ground deformation to sill intrusion is thus critical in volcanic hazard assessment. Show More Summary

Millennial-scale hydroclimate variations in southwest China linked to tropical Indian Ocean since the Last Glacial Maximum

Indian summer monsoon (ISM) variations have been linked to the orbital-scale boreal summer insolation and millennial-scale North Atlantic climates. Recent studies show the critical role of Indian Ocean sea-surface temperatures (SSTs) in affecting deglacial millennial-scale monsoon oscillations. Show More Summary

Evolution of seaward-dipping reflectors at the onset of oceanic crust formation at volcanic passive margins: Insights from the South Atlantic

Seaward-dipping reflectors (SDRs) have long been recognized as a ubiquitous feature of volcanic passive margins, yet their evolution is much debated, and even the subject of the nature of the underlying crust is contentious. This uncertainty significantly restricts our understanding of continental breakup and ocean basin–forming processes. Show More Summary

The role of F-clinohumite in volatile recycling processes in subduction zones

It is not well understood how much water and other volatiles are really contained in different mantle rocks or minerals, and how these volatiles are transported down into the deeper mantle in subduction zones. Here we present new experimental...Show More Summary

The transitional climate of the late Miocene Arctic: Winter-dominated precipitation with high seasonal variability

The late Miocene (11.6–5.3 Ma) was an important transitional period following the greenhouse conditions of the Eocene. In order to gain insight into the Arctic paleoclimate of the time, we performed high-resolution intraring 13 C analyses on fossil wood collected from the late Miocene Khapchansky sediments of northeastern Siberia (~69°N). Show More Summary

Seismic imaging of magma sills beneath an ultramafic-hosted hydrothermal system

Hydrothermal circulation at mid-ocean ridge volcanic segments extracts heat from crustal magma bodies. However, the heat source driving hydrothermal circulation in ultramafic outcrops, where mantle rocks are exhumed in low-magma-supply environments, has remained enigmatic. Show More Summary

Ina pit crater on the Moon: Extrusion of waning-stage lava lake magmatic foam results in extremely young crater retention ages

The enigmatic Ina feature on the Moon was recently interpreted to represent extrusive basaltic volcanic activity within the past 100 m.y. of lunar history, an extremely young age for volcanism on the Moon. Ina is a 2 x 3 km D-shapedShow More Summary

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