Proceedings of the Special Meeting of the Geological Society on the 3rd November, 1931. With a Half-tone Block of the Pictures of the Grabau Medal.

In opening the meeting, the chairman made the following address: "It is my agreable duty to announce and make the award of the Grabau Medal to two members of our Society, Drs. J. S. Lee and Davidson Black. "The Grabau Medal was founded in 1925 by Mr. C. Y. Wang. the then President of the Geological Society. It was so named in honor of Dr. Grabau     

Awheel in Edwardian Bedfordshire: A 1905 Geologists’ Association cycling excursion revisited and contextualised

Most of the excursions organised by the Geologists’ Association in the late 19th C. and early 20th C. were essentially pedestrian in nature. However, around the turn of the 20th C. and up to the Great War (1914–1918), the Association experimented with either specific cycling-based excursions or those that accommodated the needs of cyclist excursionists. At the time, the Association, with its London base, was ideally placed to employ the railway network as the basis for its excursions. Railways were then the principal mode of transport for middle- and long- distance journeys and were increasingly promoting suburban expansion, creating potential new field excursion areas. The railways catered for those pedestrian excursionists and cyclists who wished to venture further afield from London than was previously possible on a day- or half- day trip. The notices and reports of excursions published by the Association are examined and critiqued. The cycling excursions are examined and contextualised within a combined technological and socio-historical framework; parallels are drawn with today. A re-examination of the excursions also provides a benchmark, useful for geoconservation purposes, of the availability and accessibility of historical geosites. It can underpin new self-guided geotrails suitable for use by a wider audience than traditional geological excursionists. These various themes are explored through the consideration of a specific 1905 excursion to Bedfordshire from which general conclusions are drawn.     

Structure of the Sibumasu–Indochina collision,central Thailand: A section through the Khao Khwang Fold and thrust belt

Mainland SE Asia is composed of a number of continental fragments and volcanic arcs, separated by oceanic suture zones, which were accreted to the growing Asian continent during the Triassic Indosinian orogeny. The evolution of this orogeny has always been quite controversial. Indeed, the effects of this orogeny in Thailand have often been interpreted without considering the detailed tectonic evolution of the portion of the Indochina Block’s margin formed by Khao Khwang Platform area of the Saraburi Group, in central Thailand. This area is unusual because: (1) an extensive area representing a thin-skinned fold and thrust belt is well-exposed due to quarrying; and, (2) the fold and thrust belt displays a series of E–W and WNW–ESE striking thrusts and associated folds that are not easily explained in the context of the traditional interpretation where the terranes have been accreted broadly along N–S striking collisional zones. Detailed structural observations in numerous quarries around Highway 21 in a 13 km long dip-direction traverse have revealed that overall the thrust belt is composed of several large thrusts with an approximately northwards transport direction. In the southern part of the area, south-verging structures are present. Although the dominant structural trend is northwards-verging, interference structures, and late strike-slip faults indicate there is more than one phase of structural development present.     

Paleomagnetism of the Middle–Late Jurassic to Cretaceous red beds from the Peninsular Thailand: Implications for collision tectonics

Jurassic to Cretaceous red sandstones were sampled at 33 sites from the Khlong Min and Lam Thap formations of the Trang Syncline (7.6°N, 99.6°E), the Peninsular Thailand. Rock magnetic experiments generally revealed hematite as a carrier of natural remanent magnetization. Stepwise thermal demagnetization isolates remanent components with unblocking temperatures of 620–690 °C. An easterly deflected declination (D = 31.1°, I = 12.2°, α₉₅ = 13.9°, N = 9, in stratigraphic coordinates) is observed as pre-folding remanent magnetization from North Trang Syncline, whereas westerly deflected declination (D = 342.8°, I = 22.3°, α₉₅ = 12.7°, N = 13 in geographic coordinates) appears in the post-folding remanent magnetization from West Trang Syncline. These observations suggest an occurrence of two opposite tectonic rotations in the Trang area, which as a part of Thai–Malay Peninsula received clockwise rotation after Jurassic together with Shan-Thai and Indochina blocks. Between the Late Cretaceous and Middle Miocene, this area as a part of southern Sundaland Block experienced up to 24.5° ± 11.5° counter-clockwise rotation with respect to South China Block. This post-Cretaceous tectonic rotation in Trang area is considered as a part of large scale counter-clockwise rotation experienced by the southern Sundaland Block (including the Peninsular Malaysia, Borneo and south Sulawesi areas) as a result of Australian Plate collision with southeast Asia. Within the framework of Sundaland Block, the northern boundary of counter-clockwise rotated zone lies between the Trang area and the Khorat Basin.     

Magma Mixing of the Late Paleozoic Tayuan Complex in the Xing’an Block

Mesozoic ophiolites crop out discontinuously in the Indo‐Myanmar Ranges in NE India and Myanmar, and represent the remnants of the Neotethyan oceanic lithosphere. These ophiolites in the Indo‐Myanmar Ranges are the southern continuation of the Neotethyan ophiolites occurring along the Yarlung Zangbo Suture Zone in southern Tibet farther northwes, as indicated by their coeval crystallization ages and geochemical compositions. The Kalaymyo ophiolite is located in the central part of the Indo‐Myanmar Ranges (Myanmar). The Kalaymyo ophiolite are composed of olivine (Fo = 89.8–90.5), orthopyroxene (En86‐91Wo1‐4Fs8‐10; Mg#=89.6–91.9), clinopyroxene (En46‐49Wo47‐50Fs3‐5; Mg# = 90.9–93.6) and spinel (Mg# = 67.1–78.9; Cr# = 13.5–31.5), and have relatively homogeneous whole‐rock compositions with Mg# of 90.1–90.8 and SiO2 (41.5–43.65 wt.%), Al₂O₃ (1.66–2.66 wt.%) and CaO (1.45–2.67 wt.%) contents. They display Light Rare Earth Element (LREE)‐depleted chondrite‐normalized REE patterns and show a slight enrichment from Pr to La. The Kalaymyo peridotites are characterized by Pd‐enriched chondrite‐normalized PGE patterns with superchondritic (Pd/Ir)_CN ratios (1.15–2.36). Their calculated oxygen fugacities range between QFM–0.57 and QFM+0.90. These features collectively suggest that the Kalaymyo peridotites represent residual upper mantle rocks after low to moderate degrees (5–15%) of partial melting at a mid‐ocean‐ridge environment. The observed enrichment in LREE and Pd was a result of their reactions with enriched MORB‐like melts, percolating through these already depleted, residual peridotites. The Kalaymyo and other ophiolites in the Indo‐Myanmar Ranges hence represent mid‐ocean ridge–type Tethyan oceanic lithosphere derived from a downgoing plate and accreted into a westward migrating subduction–accretion system along the eastern margin of India.     

Ionic Composition of the Earth’s Exosphere during a Reversal of the Solar Magnetic Field

Doklady Earth Sciences - This paper analyzes measurement data on the ionic composition of the upper atmosphere at altitudes of 810–830 km in the period from 2009 to 2018; the measurements...     

Geological Characteristics and Wall Rock Alteration of Mengya’a Lead-zinc Deposit in Tibet

Please?refer?to?the?attachment(s)?for?more?details.     

Relativistic Reductions in High-Precision Measurements of the Earth’s Global Gravity Field Using a Multipair Constellation

Astronomy Reports - The theory of relativistic reductions for future challenges of space gravimetry with target accuracy of up to 1 picometer is developed in this paper.     

Evolution of manganese ore genesis in the earth’s geological history and the role of the biosphere

The formation of manganese rocks and ores occurred during the whole geological history of the Earth. Five metallogenic epochs (Early to Middle Proterozoic, Late Proterozoic, Early to Middle Paleozoic, Late Paleozoic, and Meso-Cenozoic) and 7 very important phases (Early, Middle, and Late Proterozoic, Early to Middle Paleozoic, Late Paleozoic, Late Mesozoic, and Meso-Cenozoic) can be distinguished. The phases of manganese ore genesis at many stratigraphic levels are closely related to the global climatic and tectonic reconstructions (the breakup of the continent of Gondwana and periods of glaciations and aridization) and biotic events (mass extinction of organisms). Based on carbon isotopic composition in manganese carbonates, participation of oxidized organic carbon is established.     

Block displacement fields in the Altai-Sayan region and effective rheologic parameters of the Earth’s crust

The paper is focused on recent displacement rates in the Altai-Sayan region, obtained by hydroleveling, leveling, and satellite geodesy. Effective elastic moduli and viscosity parameters of the crust are used in the modeling of coseismic and tectonic processes. The elastic moduli are determined from measurements of periodic vertical displacements during seasonal loadings of the Sayano-Shushenskaya hydropower plant. We present the results of the modeling of coseismic displacements during the earthquakes of 10 February 2011 (M = 6.1) and 27 December 2011 (M = 6.7) in Tuva and West Sayan. The results of GPS determinations for postseismic displacements in the Chuya earthquake zone (Gorny Altai, 27 September 2003, M = 7.5) are analyzed; models for the geologic medium are selected; and its effective viscosity is estimated. The tectonic component of the recent crustal displacements in the Altai-Sayan region is defined.     

Geological evolution of the Hampshire Basin (southern England) during a global climate transition from ‘hothouse’ to ‘coolhouse’ in the Palaeogene

Palaeogene sediments of the Hampshire Basin were a sensitive recorder of fluctuations in climate and eustatic sea level as Earth's climate transitioned from the global early Eocene ‘hothouse’ to the early Oligocene ‘coolhouse’, accompanied by the first permanent continent-scale glaciation of Antarctica at the Eocene/Oligocene boundary. A study of the Palaeogene sediments of the Hampshire Basin is not only interesting from a palaeoclimate perspective, but the marine middle Eocene formations are renowned for containing some of the most abundant and diverse Palaeogene fossil assemblages in the world. In this article, I take you on a tour of the geological evolution of the Hampshire Basin from the end of the Paleocene through to the Pleistocene. I highlight some of the best exposures where sediments can be studied at outcrop and representative fossil assemblages can be collected, along with the economic and archaeological significance of these Palaeogene sediments.     

Magmatic history during late Carboniferous to early Permian in the North of the central Xing’an-Mongolia Orogenic Belt: a case study of the Houtoumiao pluton,Inner Mongolia

We undertake zircon U–Pb dating, Hf isotopes, and geochemical analyses of the Houtoumiao pluton in the Xilinhot microcontinent (XLMC) in the central Inner Mongolia with an aim of determining their ages, petrogenesis, and sources, which are important for understanding the late Palaeozoic tectonic evolution of the Xing’an-Mongolia Orogenic Belt. The Houtoumiao pluton consists of medium-grained granodiorite, coarse- and medium-grained syenogranite. Mafic microgranular enclaves (MMEs) are common in the Houtoumiao pluton. Zircon U–Pb dating has yielded ages of 303 ± 2 and 301 ± 2 Ma for the granodiorite, 295 ± 2 Ma for the syenogranite, and 292 ± 1 Ma for the MMEs. The granodiorite and syenogranite have features of high-K high silica content, rich in Rb, U, and Th, but low content of HFSE, belong to calc-alkaline series. The P₂O₅ concentration decreases with the increasing SiO₂ content, suggesting I-type affinity. The MMEs, which are characterized by low SiO₂, relatively high and variable TiO₂, Al₂O₃, FeO^T, MgO, CaO, Ni, and Cr contents, also have much higher total rare earth element concentrations that the REE patterns are subparallel to those of the host rocks. Zircons from the host rocks have ε_Hf(t) values from +3.91 to +7.73 and T_DM2 values of 820–1067 Ma, suggesting that the granitoids were probably dominated by remelting of juvenile crust materials. The MMEs are of ε_Hf(t) value ranging from +6.23 to +11.04 and T_DM1 values from 490 to 693 Ma, suggesting that the primary magma probably was derived from partial melting of a depleted lithospheric mantle, the mafic mineral fractional crystallization and crustal contamination occurred during the magma evolution. Combined with previous studies on the contemporaneous magma-tectonic activities in the Uliastai Continental Margin and XLMC, we suggest that the Houtoumiao pluton formed in a post-orogenic setting.     

First report of platinum-group minerals from a hornblende gabbro dyke in the vicinity of the Southeast Extension Zone of the Voisey’s Bay Ni-Cu-Co deposit, Labrador

Summary This study reports the first documented occurrence of platinum group-minerals (PGM) in the vicinity of the Voisey’s Bay magmatic sulfide ore deposit. The PGM are present in a sulfide poor, hornblende gabbro dyke in the Southeast Extension Zone of the massive sulfide Ovoid deposit. The dyke has somewhat elevated concentrations of platinum-group elements (PGE) and gold (up to 1.95 g/t Pt, 1.41 g/t Pd, and 6.59 g/t Au), as well as Cu, Pb, Ag, Sn, Te, Bi and Sb. The PGM formed by magmatic processes and were little disturbed by subsequent infiltration of an externally-supplied hydrothermal fluid. To date, no similar PGM occurrences have been discovered in the Ovoid deposit itself. Whole rock REE patterns indicate that the dyke is geochemically related to the main conduit troctolites, which carry the bulk of the massive sulfide mineralization at Voisey’s Bay. The PGE mineralization is Pt- and Pd-rich, where the Pt and Pd occur predominantly as discrete PGM with minor Pd in solid solution in galena (average=1.8 ppm) and pentlandite (average=2 ppm). The discrete PGM are predominantly hosted by disseminated base-metal sulfides (bornite, chalcopyrite, and galena) (56 vol%) and are associated with other precious metal minerals (13 vol%) with only ∼3 vol% of the PGM hosted by silicate minerals. In whole rock samples, the PPGE (Pt, Pd, and Rh) correlate with abundances of chalcopyrite, bornite, galena, and other precious metal minerals (PMM), whereas the IPGE (Ir, Ru, and Rh) correlate with pyrrhotite and pentlandite. There are no correlations of the PGE with chlorine. Lead isotope compositions of galena associated with the PGE mineralization in the Southeast Extension Zone are broadly similar to those for galena in the Ovoid. The lead isotope compositions are much different from those in the Voisey’s Bay Syenite, which is a potential external hydrothermal fluid source. The observed Cu-rich, Pb-rich sulfide compositions and associated Pt-Pd-Au-Ag-Sn-Te-Bi-Sb assemblage in the dyke can be produced magmatically as late ISS differentiates (e.g., Prichard et al., 2004). Melting temperatures of the PGM are also consistent with a magmatic origin. Following crystallization of PGM from magmatic sulfide, an external REE-enriched hydrothermal fluid was introduced to the system, producing secondary amphibole and locally remobilizing the Pb and Sn from the sulfides hosting the PGM. Author’s address: M. A. E. Huminicki, Department of Earth Sciences, Memorial University of Newfoundland, St. John’s, NL, Canada A1B 3X5