The Tectonics of the Altaids: Crustal Growth During the Construction of the Continental Lithosphere of Central Asia Between ∼750 and ∼130 Ma Ago

2018 ◽  
Vol 46 (1) ◽  
pp. 439-494 ◽  
Author(s):  
A.M. Celâl Şengör ◽  
Boris A. Natal'in ◽  
Gürsel Sunal ◽  
Rob van der Voo
Keyword(s):  
High Resolution ◽  
Central Asia ◽  
Continental Crust ◽  
Growth Rates ◽  
Siberian Craton ◽  
Geochemical Data ◽  
Crustal Growth ◽  
Continental Lithosphere ◽  
Mountain Belt ◽  
Time Period

The largest mountain belt in Central Asia (∼9 million km2) is called the Altaids. It was assembled between ∼750 and ∼130 Ma ago around the western and southern margins of the Siberian Craton, partly on an older collisional system (the “Urbaykalides”). Geological, geophysical, and geochemical data—mostly high-resolution U-Pb ages—document the growth of only three arc systems in Central and Northwest Asia during this time period, an interval throughout which there were no major arc or continental collisions in the area. While the Altaids were being constructed as a Turkic-type orogen, continental crust grew in them by 1/3 of the global total. The Altaids thus added some 3 million km2to the continental crust over a period of 0.6 billion years, typical of Phanerozoic crustal growth rates.

scholarly journals Lake-to-Lake Cloud Bands: Frequencies and Locations

2007 ◽  
Vol 135 (12) ◽  
pp. 4202-4213 ◽  
Author(s):  
Yarice Rodriguez ◽  
David A. R. Kristovich ◽  
Mark R. Hjelmfelt
Keyword(s):  
High Resolution ◽  
Great Lakes ◽  
Satellite Imagery ◽  
Lake Superior ◽  
Great Lakes Region ◽  
Lake Effect ◽  
Time Period ◽  
High Resolution Satellite Imagery

Abstract Premodification of the atmosphere by upwind lakes is known to influence lake-effect snowstorm intensity and locations over downwind lakes. This study highlights perhaps the most visible manifestation of the link between convection over two or more of the Great Lakes lake-to-lake (L2L) cloud bands. Emphasis is placed on L2L cloud bands observed in high-resolution satellite imagery on 2 December 2003. These L2L cloud bands developed over Lake Superior and were modified as they passed over Lakes Michigan and Erie and intervening land areas. This event is put into a longer-term context through documentation of the frequency with which lake-effect and, particularly, L2L cloud bands occurred over a 5-yr time period over different areas of the Great Lakes region.

Zircon U–Pb geochronology and Hf isotope analyses of the Wulian complex in the Sulu orogenic belt, eastern China: tectonic affinity and implications for early Precambrian crustal growth and recycling in the South China Craton

2020 ◽  
pp. 1-16
Author(s):  
Jian-Hui Liu ◽  
Fu-Lai Liu ◽  
Zheng-Jiang Ding ◽  
Hong Yang ◽  
Ping-Hua Liu ◽  
...  
Keyword(s):  
Continental Crust ◽  
South China ◽  
Orogenic Belt ◽  
Detrital Zircons ◽  
Crustal Growth ◽  
Gneissic Granite ◽  
Early Precambrian ◽  
The North ◽  
South China Craton ◽  
Sulu Orogenic Belt

Abstract The Wulian complex is located on the northern margin of the Sulu orogenic belt, and was formed by collision between the North China Craton (NCC) to the north and South China Craton (SCC) to the south. It consists of the metasedimentary Wulian Group, gneissic granite and meta-diorite. The U–Pb analyses for the detrital zircons from the Wulian Group exhibit one predominant age population of 2600–2400 Ma with a peak at c. 2.5 Ga and several secondary age populations of > 3000, 3000–2800, 2800–2600, 2200–2000, 1900–1800, 1500–1300 and 1250–950 Ma; some metamorphic zircons have metamorphic ages of c. 2.7, 2.55–2.45, 2.1–2.0 and 1.95–1.80 Ga, which are consistent with magmatic-metamorphic events in the SCC. Additionally, the Wulian Group was intruded by the gneissic granite and meta-diorite at c. 0.76 Ga, attributed to Neoproterozoic syn-rifting bimodal magmatic activity in the SCC and derived from partial melting of Archaean continental crust and depleted mantle, respectively. The Wulian Group therefore has tectonic affinity to the SCC and was mainly sourced from the SCC. The detrital zircons have positive and negative ϵHf(t) values, indicating that their source rocks were derived from reworking of both ancient and juvenile crustal rocks. The major early Precambrian crustal growth took place during c. 3.4–2.5 Ga with a dominant peak at 2.96 Ga and several secondary peaks at 3.27, 2.74 and 2.52 Ga. The two oldest zircons with ages of 3307 and 3347 Ma record the recycling of ancient continental crust (> 3.35 Ga) and crustal growth prior to c. 3.95 Ga in the SCC.

Validation and comparison of high-resolution MAIAC aerosol products over Central Asia

2021 ◽  
Vol 251 ◽  
pp. 118273
Author(s):  
Xiangyue Chen ◽  
Jianli Ding ◽  
Jie Liu ◽  
Jingzhe Wang ◽  
Xiangyu Ge ◽  
...  
Keyword(s):  
High Resolution ◽  
Central Asia

Quantifying the growth of continental crust through crustal thickness and zircon Hf-O isotopic signatures: A case study from the southern Central Asian Orogenic Belt

2021 ◽  
Author(s):  
Yujian Wang ◽  
Dicheng Zhu ◽  
Chengfa Lin ◽  
Fangyang Hu ◽  
Jingao Liu
Keyword(s):  
Continental Crust ◽  
Crustal Thickness ◽  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
Crustal Thickening ◽  
Crustal Growth ◽  
Isotopic Signatures ◽  
Central Asian ◽  
Southern Central ◽  
Juvenile Crust

Accretionary orogens function as major sites for the generation of continental crust, but the growth model of continental crust remains poorly constrained. The Central Asian Orogenic Belt, as one of the most important Phanerozoic accretionary orogens on Earth, has been the focus of debates regarding the proportion of juvenile crust present. Using published geochemical and zircon Hf-O isotopic data sets for three belts in the Eastern Tianshan terrane of the southern Central Asian Orogenic Belt, we first explore the variations in crustal thickness and isotopic composition in response to tectono-magmatic activity over time. Steady progression to radiogenic zircon Hf isotopic signatures associated with syn-collisional crustal thickening indicates enhanced input of mantle-derived material, which greatly contributes to the growth of the continental crust. Using the surface areas and relative increases in crustal thickness as the proxies for magma volumes, in conjunction with the calculated mantle fraction of the mixing flux, we then are able to determine that a volume of ∼14−22% of juvenile crust formed in the southern Central Asian Orogenic Belt during the Phanerozoic. This study highlights the validity of using crustal thickness and zircon isotopic signatures of magmatic rocks to quantify the volume of juvenile crust in complex accretionary orogens. With reference to the crustal growth pattern in other accretionary orogens and the Nd-Hf isotopic record at the global scale, our work reconciles the rapid crustal growth in the accretionary orogens with its episodic generation pattern in the formation of global continental crust.

scholarly journals Continental lithosphere folding in Central Asia (part I): Constraints from geological observations

1993 ◽  
Vol 226 (1-4) ◽  
pp. 59-72 ◽  
Author(s):  
A.M. Nikishin ◽  
S. Cloetingh ◽  
L.I. Lobkovsky ◽  
E.B. Burov ◽  
A.C. Lankreijer
Keyword(s):  
Central Asia ◽  
Continental Lithosphere

scholarly journals Non-subduction petrological mechanisms for the growth of the neoarcheam continental crust of the Kola–Norwegian terrane, Fennoscandian shield: geological and isotope-geochemical evidence

2019 ◽  
Vol 27 (2) ◽  
pp. 161-186
Author(s):  
A. B. Vrevskii
Keyword(s):  
Continental Crust ◽  
Greenstone Belt ◽  
Geochemical Modeling ◽  
Volcanic Rocks ◽  
Fennoscandian Shield ◽  
Crustal Growth ◽  
Calc Alkaline ◽  
Geochemical Evidence

The paper reports new data on the composition and age of the Neoarchean calc-alkaline volcanic rocks of the Uraguba–Kolmozero–Voron’ya greenstone belt (UKV GB). Petrological-geochemical modeling indicates a polygenetic origin of primary melts of the basalt–andesite–dacite association and non-subduction geodynamic mechanisms for the crustal growth in the largest greenstone belt of the Kola–Norwegian Block of the Fennoscandian shield.

A new terrane subdivision for Mongolia: implications for the Phanerozoic crustal growth of Central Asia

2002 ◽  
Vol 21 (1) ◽  
pp. 87-110 ◽  
Author(s):  
Gombosuren Badarch ◽  
W Dickson Cunningham ◽  
Brian F Windley
Keyword(s):  
Central Asia ◽  
Crustal Growth

A 2200-yr record of hydrologic variability from Foy Lake, Montana, USA, inferred from diatom and geochemical data

2006 ◽  
Vol 65 (02) ◽  
pp. 264-274 ◽  
Author(s):  
Lora R. Stevens ◽  
Jeffery R. Stone ◽  
Josh Campbell ◽  
Sherilyn C. Fritz
Keyword(s):  
Spectral Analysis ◽  
High Resolution ◽  
High Frequency ◽  
Lake Level ◽  
Low Frequency ◽  
Seasonal Distribution ◽  
Geochemical Data ◽  
Hydrologic Variability ◽  
Moisture Balance ◽  
Hydrologic Balance

AbstractA 2200-yr long, high-resolution (∼5 yr) record of drought variability in northwest Montana is inferred from diatoms and δ18O values of bio-induced carbonate preserved in a varved lacustrine core from Foy Lake. A previously developed model of the diatom response to lake-level fluctuations is used to constrain estimates of paleolake levels derived from the diatom data. High-frequency (decadal) fluctuations in the de-trended δ18O record mirror variations in wet/dry cycles inferred from Banff tree-rings, demonstrating the sensitivity of the oxygen-isotope values to changes in regional moisture balance. Low frequency (multi-centennial) isotopic changes may be associated with shifts in the seasonal distribution of precipitation. From 200 B.C. to A.D. 800, both diatom and isotope records indicate that climate was dry and lake level low, with poor diatom preservation and high organic carbon: nitrogen ratios. Subsequently, lake level rose slightly, although the climate was drier and more stable than modern conditions. At A.D. 1200, lake level increased to approximately 6 m below present elevation, after which the lake fluctuated between this elevation and full stage, with particularly cool and/or wetter conditions after 1700. The hydrologic balance of the lake shifted abruptly at 1894 because of the establishment of a lumber mill at the lake's outlet. Spectral analysis of the δ18O data indicates that severe droughts occurred with multi-decadal (50 to 70 yr) frequency.

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