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Hainan Island is located at the intersection of the India–Australian, Philippine–Pacific, and Eurasian plates. As a key component of Southeast Asia, constraints on the tectonic evolution of Hainan Island can help researchers to understand the evolutionary process of SE Asia more thoroughly. This study reports 960 new detrital zircon U–Pb ages of 8 samples from the Silurian, Pennsylvanian, and Middle Triassic strata on Hainan. Detrital zircon grains from the Silurian samples yield five dominant age populations of 460–420 Ma, 600–500 Ma, 1200–1000 Ma, 2000–1400 Ma, and 2700–2400 Ma. There are high similarities in age distributions between the Silurian and Pennsylvanian samples, but the Pennsylvanian samples exhibit a special age population of 360–340 Ma. The Middle Triassic samples have a relatively simple detrital zircon age distribution pattern with a dominant age peak at ca. 250 Ma and a subordinate age group of 390–360 Ma. The Silurian strata on Hainan Island mainly receive detritus from the South China Block and Eastern Gondwana, and detrital zircon grains from the Pennsylvanian samples were derived from the recycled strata on Hainan Island except that ca. 350 Ma grains came from the Early Carboniferous bimodal volcanic rocks near the Pennsylvanian sample site. Detrital zircons of the Middle Triassic samples are mainly derived from the ca. 250 Ma collision-related arc materials and the recycled strata. Based on detrital zircon geochronological data and previous results, we proposed a new tectonic model for the late Paleozoic tectonic evolution of Hainan Island. The Carboniferous drifting of Hainan Island northward resulted in a back-arc basin developed on central Hainan Island. At ca. 330 Ma, this back-arc basin turned into an oceanic basin, and this oceanic basin continued to develop during the Early–Middle Permian. Due to the closure of this oceanic basin since the late Middle Permian, the North Hainan finally collided with the South Hainan along the Bangxi–Chenxing tectonic belt and consolidated to form a unified Hainan Island again at ca. 250 Ma.

We review paleontologic evidence from the Upper Ordovician to Devonian strata in the Korean Peninsula and discuss their tectonostratigraphic origin. The Upper Ordovician–Devonian fossil-bearing strata are largely distributed in North Korea, and tectonostratigraphically in the southern margin of the Pyeongnam Basin and in the northern part of the Imjingang Belt. The fossils have been regarded as evidence that the “great hiatus” of the middle Paleozoic is not a prevalent phenomenon across the Sino-Korean Block. Examination of selected fossils with stratigraphic and paleogeographic significance reveals that the fossils from the Sangsori, Koksan and Wolyangri series and the Rimjin System are of the Late Ordovician to Devonian and display affinity to those of the coeval strata of South China. In addition, the fossils included within clasts of the Songrim Conglomerate, the basal unit of the Jurassic Taedong System, are of the Silurian to Devonian, which also display affinity to South China. The faunal and floral affinity suggests that the Upper Ordovician to Devonian strata in North Korea most likely formed in a basin(s) of or peripheral to the South China Block, which indicates that the strata are allochthonous, contrary to the traditional interpretation of their autochthonous origin by North Korean geologists. The Permo-Triassic collision between the two Chinese cratons which resulted in the amalgamation of three massifs of the Korean Peninsula is considered to be responsible for the accretion and juxtaposition of the Upper Ordovician to Devonian strata onto the Sino-Korean Block. The autochthonous origin of the strata suggests the absence of the “great hiatus” at least in North Korea, whereas the allochthonous origin its presence across the Sino-Korean Block.

In the central Klamath Mountains, the Eastern Hayfork terrane (EHF) accreted directly seaward of the North Fork ophiolitic arc. The EHF trench mélange consists of very fine-grained, quartzose meta-argillite + boudinaged metachert layers as well as scattered blocks derived from both oceanic and inboard arc-margin sources. Among the exotic blocks are coarse-grained feldspathic metasandstones. Detrital zircon SHRIMP U-Pb ages ranging from the latest Archean to the early Proterozoic were reported by Scherer and colleagues in 2010 for five metasandstone blocks from the central and southern Klamaths; Phanerozoic zircons were totally lacking. It was concluded that the blocks were olistostromal and that erosion of a nearby thrust sheet outlier of the Proterozoic Antelope Mountain Quartzite of the Eastern Klamath belt, Yreka subterrane, was a likely source. To determine the provenance and time of deposition of the EHF muddy matrix host of the metasandstone blocks, we separated zircons from three very fine-grained, intimately interstratified, feldspar-poor meta-argillites from the Sawyers Bar map area. New laser ablation multicollector inductively coupled plasma mass spectrometry zircon U-Pb data indicate maximum sedimentary ages for the meta-argillites as ∼272, ∼211, and ∼201 Ma. Thus, the muddy strata were deposited near the end of Triassic time. The meta-argillites contain scattered Proterozoic and Paleozoic–early Mesozoic detrital zircons, indicating local inboard Klamath sources, including the Antelope Mountain Quartzite thrust sheet. St. Clair Creek distal turbidites in the landward North Fork terrane contain Paleozoic and Triassic–Early Jurassic (∼188 Ma) zircons as well as scattered Precambrian grains similar to those in the EHF. The EHF surficially docked against the North Fork terrane by ∼174–173 Ma because the amalgamated but unmetamorphosed terrane contact was invaded by the English Peak plutonic complex beginning at ∼172 Ma. Regional metamorphism and deformation took place throughout the central Klamath Mountains during the Siskiyou transpressive accretionary event at ∼170–168 Ma.

We estimate the effects of three biases on the observed alpha diversity of paleocommunities from the Middle Paleozoic and Late Cenozoic. The first bias results from the preferential dissolution of aragonite relative to calcite, this bias can lower the relative abundance and preserved diversity of aragonitic taxa, potentially lowering the rarefied diversity of an entire fossil assemblage. We model the effects of this bias by analytically reinserting aragonitic specimens and taxa into Paleozoic assemblages that have been described in the literature. The aragonitic specimens are inserted using a range of reasonable assumptions about the original local paleocommunity composition. Although the dissolution bias is probably not as severe as has been argued by some, our analytical modelling indicates that the average Paleozoic assemblage may have lost up to 29% of its total diversity. The second bias results from the higher diversity of the tropics relative to temperate latitudes, but the Late Cenozoic collections we analyzed from the literature represent temperate assemblages whereas the Paleozoic collections were tropical in origin (the northward drift of North America and Europe through time caused this difference). On the basis of the latitudinal diversity gradients in the Late Cenozoic, the diversity of the temperate Late Cenozoic samples should be at least doubled for an accurate comparison to the tropical Paleozoic samples. The third bias is environmental: our Late Cenozoic samples tend to come from more onshore, stressed habitats than the Paleozoic samples. In our study, this factor should reduce the apparent diversity of Late Cenozoic paleocommunities by about 9%. After correcting for these biases, standardized alpha diversity appears to increase by a factor of 3.0-3.7 from the Middle Paleozoic to the Late Cenozoic. Previous studies that did not correct for these biases suggested that alpha diversity increased by a factor of 2.5 times; the earlier studies produced approximately correct results because (by chance) the effects of the biases largely cancel out. In the \"consensus\" article on marine diversity history, an observed increase in alpha diversity was taken as powerful support for an increase in global diversity from the Paleozoic to the Cenozoic. Although we do not test all conflating factors, this study provides new rigor to this longstanding view of alpha diversity change in the Phanerozoic.

The diversity of the material composition of the middle Paleozoic basites is determined by the geodynamic regime. Paleoriftdike belt record several groups of basites, differing in their material composition. The most common basites were formed in the regime of extension - magma has not experienced significant changes after leaving magma formation zone. These are typical basites of the Middle Paleozoic paleorifts of the eastern part of the Siberian platform. Group of leucocratic gabbro-dolerites and plagiodolerites, which were formed when extension was changed to compression at the peripheral zones of dike belts. Such magmatites reflect manifestation of lateral zonation within the limits of thick dike belts. A separate group consists of the bodies of magmatites, which material composition records long-term fractionation of the melt in pre-chamber deep-seated setting. As a result of long-term closing of the system, anorthosite or monzonite type of magma differentiation are formed in deep-seated magmatic chambers. The unique nature of the Vilyui and Olenek paleorifts is in combination, within their limits, of basic and kimberlitic magmatism. Dikes of high-Ti basites localized nearby the kimberlite pipes form a separate group. As regards the time of emplacement, the dikes within the limits of the Nakyn kimberlite field are post-kimberlitic. Chemical composition of the basites is specifically characterized by high TiO2 content (up to 5%). Besides, they are slightly undersaturated in silicic acid and contain higher contents of K2O and volatile constituents. Figurative compositional points of the basites plot mainly into the field of the subbalkaline series. Alkali basites within the Nakyn kimberlite field are shown to have metamagmatic origin and, along with the accompanying explosive breccias, are good indicators of fluid permeable zone and kimberlite-controlling structures. Locality of their distribution, closeness in time to kimberlites make it possible to use intrusives of alkaline basites as prospecting indicators of primary diamond deposits.

Both vertical uplift and lateral extrusion of rocks in convergent orogens have been widely documented. This article, using the basement core of the Qinling orogen as an example, demonstrates orogen-parallel westward uplift with both vertical and horizontal displacement components. The Qinling complex of the Qinling orogen is a tectonic slice of a Precambrian crystalline basement. It is an elongate lens between younger terranes bounded by the Shangdan suture to the south and by the Zhuxia zone to the north. During the middle Paleozoic, the complex underwent large-scale orogen-parallel westward oblique ductile uplift. Supporting evidence for this includes the following: (1) opposite shear senses of the two bounding shear zones, i.e., the thrust-sinistral shear on the south and thrust-dextral shear on the north; (2) well-developed eastward plunging (orogen-parallel) A-type structures in the complex, such as stretching lineation and sheath folds; (3) strong decompression metamorphism of the complex from 0.66 GPa to 0.45 GPa and eclogites decompressed from 1.2 GPa to 0.5 GPa; and (4) eastward migration in the emplacement of synkinematic granitic plutons. Integrated analysis of PT evolution paths suggests a vertical uplift of the basement complex relative to adjacent Paleozoic supracrustal rocks ranging from 15 to 40 km. Coeval west-directed horizontal displacement is then estimated to range from 32 to 86 km and total oblique displacement from 36 to 95 km, using an average 25° plunge of mineral stretching lineations in the boundary shear zones. This oblique uplift could be explained by soft oblique extrusion derived from a scissors-like (or zipped) subduction/collision between the North and South Qinling belts. Because plate boundaries are usually irregular and nonparallel both in the vertical and horizontal, orogen-parallel oblique uplift (soft oblique extrusion) may be widespread in collisional orogens.

A middle Paleozoic subduction-collision orogenic belt between the Siberian and North China Plates has been recognized in Xilinhot-the south of Sonid Left Banner-Erdaojing area, northern Inner Mongolia, China. It comprises five subunits: melange belt, foreland deformation belt, molasse and littoral basin, arc diorite series and syn-collision granitoid series. Evolution history of the orogenic belt can be divided into subduction stage (500-400 Ma) and collision stage (400-320 Ma). The formation of the orogenic belt caused the convergence between the Siberian and North China Plates during the late Devonian. Suture zone corresponding to the melange belt extends from Erdao-jing, Qagan Ura to Honggor.

A large number of specimens (∼500) of the hyolithid Hallotheca cf. aclis (Hall) were collected from the Middle Devonian Arkona Shale at Hungry Hollow, Ontario, Canada. This is an unusually large sample for Devonian hyolithids and only the second record of hyolithids from the Michigan Basin. Furthermore, the conchs of seven specimens are bored, and the holes are single, complete, circular in plan view, and with their long axes perpendicular to the walls of the conch. These traits and the fact that the holes are stereotyped with respect to the side of the conch—all occur on the venter—are consistent with a predatory origin of the holes. Although bored specimens represent only ∼1% of the sample, this record expands the taxonomic breadth of bored prey during the middle Paleozoic, a time previously recognized as characterized by intensification of predator-prey interactions.

U-Pb and 40Ar/39Ar dates from the Talladega belt, southernmost Appalachians, provide insight into the timing and nature of pre-Alleghanian tectonism in this region. Low-grade metasedimentary rocks of the Talladega belt represent the outermost preserved portions of the southern Laurentian margin, thus recording the earliest orogenic events that affected the margin, in addition to later overprinting events. These rocks are structurally overlain by the Hillabee Greenstone metavolcanic sequence, from which metadacite yields an age of 470±4 Ma (ion microprobe U-Pb zircon age). Hillabee geochemistry indicates formation in an arc or back-arc setting. We suggest correlation of the Hillabee Greenstone with 460-470-Ma arc-related rocks in the Dahlonega gold belt, which extends along strike with the Hillabee through Georgia and into North Carolina, and interpret the Hillabee as the southernmost volcanic expression of an Early-Middle Ordovician arc that formed outboard of Laurentia. Rocks of the Talladega belt, including the Hillabee, preserve a record of only one Paleozoic dynamothermal metamorphic event. 40Ar/39Ar dates are consistent with metamorphism following deposition of the youngest biostratigraphically dated unit, the Erin Slate, which contains early Mississippian Periastron plant fossils (360-350 Ma). Muscovite (closure temperature 350°-400°C) yields internally consistent ages between 334 and 320 Ma. Metamorphism of the Talladega belt, therefore, is constrained to the interval between 360 and 320 Ma. The pre- to synmetamorphic thrust contact between the Hillabee Greenstone and Talladega belt metasedimentary rocks must have formed after deposition of the Erin Slate at 360-350 Ma but before metamorphism of the Talladega belt (no later than ∼320 Ma). We propose that the Ordovician Hillabee-Dahlonega arc terrane first collided with the Laurentian continental margin between 360 and 320 Ma, with variations in timing of deformation and metamorphic character along the collision zone.

The results of the K-Ar, Rb-Sr, and U-Pb (SHRIMP zircon method) dating of the Middle Paleozoic volcanogenic rocks of the Omolon Massif are summarized. It was concluded that they are principally consistent with each other, as well as with the geological data. The formation of the Kedon Group, which makes up the main volume of the Middle Paleozoic volcanics, began at the Early-Middle Devonian boundary about 400 Ma ago (U-Pb dates of 400.5 ± 4.4 and 387 ± 6.4; Rb-Sr isochron age of 402 ± 6 Ma). The isotopic age of the upper boundary of the Kedon Group remains unclear due to disagreements concerning its stratigraphic assignment. The histogram based on the 111 K-Ar dates of the volcanic rocks from the Kedon Group gives a polymodal distribution, which indicates that the K-Ar isotopic system was disturbed by thermal events, which occurred 310–290 (terminal Carboniferous—beginning of the Permian) and 240–220 (Middle-beginning of the Late Triassic) Ma ago. Both thermal events were associated with mantle (ultrabasic-basic) magmatism, which spanned a significantly wider territory than the distribution area of the Kedon Group