Catalogue Search | MBRL
Search Results Heading
Explore the vast range of titles available.
MBRLSearchResults
-
DisciplineDiscipline
-
Is Peer ReviewedIs Peer Reviewed
-
Reading LevelReading Level
-
Content TypeContent Type
-
YearFrom:-To:
-
More FiltersMore FiltersItem TypeIs Full-Text AvailableSubjectPublisherSourceDonorLanguagePlace of PublicationContributorsLocation
Done
Filters
Reset
4,206
result(s) for
"exhumation"
Sort by:
The history and politics of exhumation : royal bodies and lesser mortals
This book argues that a serious, scholarly study on exhumation is long overdue. Examining more well-known cases, such as that of Richard III, the Romanovs, and Tutankhamen, alongside the more obscure, Michael Nash explores the motivations beyond exhumation, from retribution to repatriation. Along the way, he explores the influence of Gothic fiction in the eighteenth century, the notoriety of the Resurrection Men in the nineteenth century, and the archeological heyday of the twentieth century.
Arc-continent collisions in the tropics set Earth’s climate state
by
Jagoutz, Oliver
,
Lisiecki, Lorraine
,
Macdonald, Francis A.
in
Carbon
,
Carbon dioxide
,
Carbon sequestration
2019
On multimillion-year time scales, Earth has experienced warm ice-free and cold glacial climates, but it is unknown whether transitions between these background climate states were the result of changes in carbon dioxide sources or sinks. Low-latitude arc-continent collisions are hypothesized to drive cooling by exhuming and eroding mafic and ultramafic rocks in the warm, wet tropics, thereby increasing Earth’s potential to sequester carbon through chemical weathering. To better constrain global weatherability through time, the paleogeographic position of all major Phanerozoic arc-continent collisions was reconstructed and compared to the latitudinal distribution of ice sheets. This analysis reveals a strong correlation between the extent of glaciation and arc-continent collisions in the tropics. Earth’s climate state is set primarily by global weatherability, which changes with the latitudinal distribution of arc-continent collisions.
Journal Article
Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): Insights from the geological setting of the lherzolite bodies
by
Lagabrielle, Yves
,
de Saint Blanquat, Michel
,
Labaume, Pierre
in
Earth Sciences
,
Environmental Sciences
,
Global Changes
2010
The Pyrenean peridotites (lherzolites) form numerous small bodies of subcontinental mantle, a few meters to 3 km across, exposed within the narrow north Pyrenean zone (NPZ) of Mesozoic sediments paralleling the north Pyrenean Fault. Recent studies have shown that mantle exhumation occurred along the future NPZ during the formation of the Albian‐Cenomanian Pyrenean basins in relation with detachment tectonics. This paper reviews the geological setting of the Pyrenean lherzolite bodies and reports new detailed field data from key outcrops in the Béarn region. Only two types of geological settings have to be distinguished among the Pyrenean ultramafic bodies. In the first type (sedimented type or S type), the lherzolites occur as clasts of various sizes, ranging from millimetric grains to hectometric olistoliths, within monogenic or polymictic debris flow deposits of Cretaceous age, reworking Mesozoic sediments in dominant proportions as observed around the Lherz body. In the second type (tectonic type or T type), the mantle rocks form hectometric to kilometric slices associated with crustal tectonic lenses. Both crustal and mantle tectonic lenses are in turn systematically associated with large volumes of strongly deformed Triassic rocks and have fault contacts with units of deformed Jurassic and Lower Cretaceous sediments belonging to the cover of the NPZ. These deformed Mesozoic formations are not older that the Aptian‐early Albian. They are unconformably overlain by the Albian‐Cenomanian flysch formations and have experienced high temperature‐low pressure mid‐Cretaceous metamorphism at variable grades. Such a tectonic setting characterizes most of the lherzolite bodies exposed in the western Pyrenees. These geological data first provide evidence of detachment tectonics leading to manle exhumation and second emphasize the role of gravity sliding of the Mesozoic cover in the preorogenic evolution of the Pyrenean realm. In the light of such evidence, a simple model of basin development can be inferred, involving extreme thinning of the crust, and mantle uprising along a major detachment fault. We demonstrate coeval development of a crust‐mantle detachment fault and generalized gravitational sliding of the Mesozoic cover along low‐angle faults involving Triassic salt deposits as a tectonic sole. This model accounts for the basic characteristics of the precollisional rift evolution in the Pyrenean realm.
Journal Article
Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars
2015
Since 2012, the Curiosity rover has been diligently studying rocky outcrops on Mars, looking for clues about past water, climate, and habitability. Grotzinger
et al.
describe the analysis of a huge section of sedimentary rocks near Gale crater, where Mount Sharp now stands (see the Perspective by Chan). The features within these sediments are reminiscent of delta, stream, and lake deposits on Earth. Although individual lakes were probably transient, it is likely that there was enough water to fill in low-lying depressions such as impact craters for up to 10,000 years. Wind-driven erosion removed many of these deposits, creating Mount Sharp.
Science
, this issue p.
10.1126/science.aac7575
, see also p.
167
Mount Sharp now stands where there was once a large intercrater lake system.
[Also see Perspective by
Chan
]
The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp).
Journal Article
Exhumation rates in the Gran Paradiso Massif (Western Alps) constrained by in situ U–Th–Pb dating of accessory phases (monazite, allanite and xenotime)
2018
Exhumation rates for high-pressure metamorphic rocks need to be carefully estimated to decipher tectonic processes in subduction/collision belts. In the Gran Paradiso Massif (Western Alps), the Money Unit crops out as a tectonic window below the Gran Paradiso Unit. According to previous studies, the Gran Paradiso and Money Units reached peak pressure conditions at ~ 18 to 20 kbar, 480–520 °C and ~ 17 to 18 kbar, 500–550 °C, respectively. This yields a maximum difference of ~ 9 to 10 km in the subduction depth reached by these two units during the Alpine history. Thrusting of the Gran Paradiso Unit over the Money Unit led to the simultaneous development of the main foliation under the same metamorphic conditions (~ 12.5 to 14.5 kbar and 530–560 °C) in both units. The thrust contact was subsequently folded and then both units were exhumed together. The relative timing of the growth and dissolution of the accessory phases was assessed by combining thermodynamic modelling with inclusion, textural and chemical (major and trace element) data from both major and accessory phases. The age of monazite constrained the high-pressure metamorphism in both the Gran Paradiso Unit and the Money Unit at 41.5 ± 0.3 and 42.0 ± 0.6 Ma, respectively. Allanite replacing monazite in the matrix has been dated at 32.7 ± 4.2 Ma. The late growth of xenotime associated with the crystallization of biotite pseudomorphs at the expense of garnet (at about 10 kbar) was dated at 32.3 ± 1.0 Ma. Our petrochronological data indicate about 10 m.y. between the peak pressure conditions and the crystallization of xenotime leading to an exhumation rate of the order of 2.2–5 mm/year. The new ages allow to better constrain the timing of the displacement of the thrust defining the lower boundary of the extruding wedge of eclogite-facies rocks.
Journal Article
Multi‐Stage Magmatism During Slab Exhumation Drives the Geochemical Evolution of Continental Crust: Insights From Paleozoic Granitoids in South Altyn, Western China
by
Gai, Yongsheng
,
Chen, Danling
,
Cao, Yuting
in
Biotite
,
Continental crust
,
continental subduction/exhumation
2024
The present continental crust is characterized by a felsic upper crust and a mafic lower crust, resulting from significant geochemical differentiation over geological time. While various processes have been proposed to explain this differentiation, subduction zones remain pivotal regions for understanding the compositional evolution of continental crust. This study focuses on the South Altyn (SA) continental subduction‐collision belt in western China, a unique setting that experienced ultra‐deep (>300 km) continental subduction followed by multi‐stage exhumation. We present a comprehensive study of four granitoid suites from Tatelekebulake (TTLK) area in SA: biotite granite (BG), monzogranite (MG), K‐feldspar granite (KG), and leucogranite (LG). Comprehensive studies on petrology, geochemistry and zircon U‐Pb dating show that these granitoids formed at 494, 451, 414, and 418 Ma, respectively, and originated from protoliths with affinity to the subducted continental crust in SA. Phase equilibrium modeling suggests that BG formed at ∼800°C and 0.6 GPa, while the MG, KG, and LG formed by differentiation crystallization of the BG magma under progressively decreasing temperature and pressure conditions (750°C, 0.5 GPa; 740–700°C, 0.2 GPa; and 700–640°C, 0.1 GPa, respectively). These results, combined with previous studies, allow us to reconstruct the tectonic processes of continental exhumation and subsequent orogenic collapse in SA during the Early Paleozoic. Importantly, our findings reveal that magmatism derived from partial melting of subducted continental crust can promote the geochemical evolution of continental crust toward more felsic compositions, even in the absence of significant crustal growth or mantle‐derived magmatism. This study provides a valuable case for understanding the compositional evolution of continental crust in deep subduction zones and challenges conventional models that rely heavily on arc magmatism for crustal differentiation. Moreover, our results contribute to a broader understanding of crustal evolution processes in collisional orogens worldwide and highlight the importance of recycling and differentiation of subducted continental material in shaping crustal compositions. Plain Language Summary The geochemical evolution of the continental crust, from mafic composition 3 billion years ago to current composition stratified structure, is commonly believed to be driven by crustal growth through arc magmatism and undergoes a series of subsequent complex geodynamic processes. The study of the Early Paleozoic multi‐stage magmatism related to continental crust subduction and exhumation in the Tatelekebulake region of South Altyn western China reveals the differentiation, evolution and material cycling occurring in the absence of prominent arc magmatism mechanisms within the upper to middle crust range and provides a new scenario of the evolution of the continental crust, and crustal growth. This process could drive the upper continental crust toward a more felsic composition, while the middle to lower continental crust becomes more mafic characteristics. Key Points The geochemistry characteristics of the four samples suggest derivation from the subducted continental crust The study revealed multi‐stage magmatism associated with continental crust subduction and subsequent exhumation Partial melting of subducted continental crust can promote the geochemical evolution of continental crust toward more felsic compositions
Journal Article