Abstract This is the first supplement to the Annotated Bibliography of the World Literature on the Grand Canyon Type Fossil Chuaria circularis Walcott, 1899. The reader is referred to extensive introductory material that appeared in Vol. 3 of the Grand Canyon bibliography (Spamer, 1988, Geol. Soc. America Microform Pub. 17). As with the first installment of this bibliography, the entries are arranged chronologically by year; within each year the entries are arranged alphabetically by author names.

Abstract This annotated bibliography is a guide to the literature on Chuaria Walcott, 1899, currently understood to be a nmnospecific genus represented by C. circularis Walcott, to which a number of other taxa have been referred in taxonomic synonymy. Because of the taxonomic complications in defining Chuaria , systematic and paleobiological discussions are avoided in the introductory remarks presented herein; such discussions are beyond the scope of a bibliography. Therefore, Chuaria is treated herein in a broad sense ( Chuaria, sensu lato ), which encompasses C. circularis , all other species which have been erected within the genus, and all those taxa which various authors have placed in synonymy with C. circularis or one of its synonyms. Throughout this bibliography, unless stated otherwise, all references to Chuaria implies C. circularis and its real and presumed synonyms. All these taxa can, at least right now, be placed within the broad morphological definition of Chuaria. The morphological descriptions of the synonymous taxa arti too diverse to satisfy most taxonomists. The diversity is due in large part to different depositional environments, taphonomic processes v affecting the preservation of the fossils, different study techniques, and changing contemporary understanding of this fossil and late Proterozoic paleobiology overall. The obvious purpose of this bibliography is to present synopses of the nearly 150 publications which mention or discuss Chuaria . But of more importance to the researcher is the presentation of appropriate quotations regarding this fossil, in some instances the entire entry which refers to it. Also included herein are complete quotations of the original descriptions of Chuaria and its synonyms.

Abstract An enigmatic quartzite breccia previously mapped within a late Neoproterozoic–Early Paleozoic unit exposed in Leaton Gulch near Challis, Idaho, U.S.A., may be related to the Beaverhead meteorite impact. The fragments in the breccia are highly deformed, but no unequivocal features of shock metamorphic deformation have been observed. The brecciated rocks are entirely in the late Mesoproterozoic Swauger Formation. The Swauger overlies crumpled rocks of the younger Mesoproterozoic Lawson Creek Formation, across a planar and nearly flat surface interpreted to be a thrust fault. Neither the planar surface nor the breccia is crumpled. The breccia is part of a thrust slice carried into the Leaton Gulch area from farther west during the Late Cretaceous thrust faulting characteristic of this region. The erosion– smoothed upper surface of the breccia is overlain by the Wilbert Formation of Neoproterozoic–Early Cambrian age. The Wilbert, in turn, is overlain by the Middle Ordovician Kinnikinic Quartzite. The age of the breccia therefore must be post–Swauger and pre–Wilbert, and Neoproterozoic. The breccia could be debris that fell from one of the outermost ring faults defining the impact crater. Such rocks would have been too far away from the point of impact to experience pressures sufficient to cause any shock deformation.

Abstract This is the third volume (second supplement) to the series, Geology of the Grand Canyon: An Annotated Bibliography with An Annotated Catalogue of Grand Canyon Type Fossils . The first two volumes were published in 1983 and 1984, respectively, as Geological Society of America Microform Publications 13 and 14. The current volume cites references published as late as September, 1987, but by no means does this imply that the bibliography or lists of new fossil taxa are comprehensive to that date. This work is very much an ongoing project. Of special note in Volume 3 is the inclusion of a third part, “An annotated Bibliography of the World Literature on the Grand canyon Type Fossil Chuaria circularis Walcott, 1899, an Index Fossil for the Late Proterozoic” This bibliography was prepared as a separate publication. However, it is apparent from reading the very recent literature (see particularly Sun, 1987) that Chuaria should not be relied upon as an infallible index fossil for the late Proterozoic. The fossil is somewhat unreliable not because of poor stratigraphie resolution, but that it is difficult to identify on morphological characters alone. Instead, the assemblage of Chuaria Walcott, 1899, and Tawuia Hofmann, 1979, are regarded as a reliable index fossil assemblage when they occur together (Sun, 1987). Chuaria (and itc many synonyms) has had such a remarkable research history, since as early as 1876, found worldwide, that it seems appropriate to present this bibliography in its historical context as one of a particularly enigmatic Grand Canyon Type Fossil. Chuaria clearly was known to science a century before the associated Tawuia was described by Hofmann (in Hofmann 6 Aitken, 1979). Recent research on these taxa has burgeoned in the world literature. Their biologic affinities are known with reasonable certainty, but we are still pretty much at a loss to satisfactorily describe Chuaria taxonomically even though it is one of the few

Abstract Our studies of the Neoproterozoic Uinta Mountain Group focus on the Red Pine Shale in the western Uinta Mountains and the undivided clastic strata in the eastern Uinta Mountains, which record deltaic-marine and braided-fluvial to shoreline deposition, respectively. We conclude that the Red Pine Shale postdates the < 770 Ma eastern clastic strata, and the Uinta Mountain Group represents deposition in a rift basin predating the rift episode recorded at ~ 700 Ma in western Laurentia. Measured sections and stratigraphic mapping of the Red Pine Shale show that it is ~ 550-1200 m thick in the western part of the range, thins to < 300 m in the east-central range, and is missing in the eastern range. Measured sections show organic-rich shale interbedded with medium- to coarse-grained sandstone. Sedimentary structures include graded bedding, hummocky cross stratification, parallel to ripple lamination, tabular crossbeds, ripple marks, and slump folds. Fossils include Bavlinella faveolata, filaments, leiosphaerid acritarchs, and, more rarely, vase-shaped microfossils and ornamented acritarchs. Preliminary whole-rock δ 13 Corg analysis of organic-rich shales reveal 13.9%o (PDB) variability (values range from -16.9 to -30.8%o PDB) and TOC values range from 0.07 to 5.9%. Combined data suggest deposition below and near fair-weather wave base in a marine deltaic system, and correlation with the ~ 770 to > 742 Ma Chuar Group, Grand Canyon. The undivided clastic strata of the Uinta Mountain Group, eastern Uinta Mountains, are dominated by trough- and tabular-cross- bedded and massive sandstone showing south-southwestern paleocurrent flow. At least three laterally continuous (kilometer-scale) ~ 50-m-thick intervals of gray-green, organic-bearing shale have been mapped amongst these sandstone intervals and contain ripple marks, mud-crack casts, ripple cross laminae, and gypsum casts and molds. The lowermost shale interval allows subdivision of the clastic strata into three informal units. Fossils from shale in the middle-upper (?) interval of the clastic strata include acritarchs and possible vase-shaped microfossils. Simple sphaeromorphs and carbonaceous filaments have also been found in black to green shale near the base of the section. The clastic strata represent a sandy braid system with possible marine drowning events from the west. In addition to an alluvial-fan setting, the Jesse Ewing Canyon Formation, the basal unit of the UMG below the clastic strata, represents high-energy shoreline and fan-delta deposition.

Abstract This supplement to the Annotated Catalogue of Grand Canyon Type Fossils contains six species new to the catalogue, and one entry which was listed as being in Volume 1 but which was inadvertently omitted. The species list of Grand Canyon Type Fossils is also updated herein and is cross-indexed to all three volumes. The opportunity is taken herein to also update entries for Chuaria circularis Walcott and for Melanocyrillium Bloeser, spp. The updated entry for C. circularis complements Part III of this volume, the annotated bibliography of the world literature on Chuaria. To maintain continuity with Volumes 1 and 2, these entries are retained in the Miscellanea, with reference to the Acritarcha. More discussions on Chuaria will be found in Part III of this volume. The format followed in Volume 3 is the same as that followed in the first two volumes. The reader is referred to introductory remarks in the earlier volumes for addi onal information.

Abstract Platform sediments of Iran span the Late Ediacaran and extend into the Palaeozoic. They are primarily clastic and carbonaceous in nature, deposited in coastal and lagoonal settings. They crop out in the Takab area, as the Soltanieh Formation (Late Proterozoic to Atdabanian), the Barut Formation (Early Bottomian), the Zaigun Formation (Middle Bottomian), the Lalun Formation (Late Bottomian) and the Mila Formation (Middle Cambrian to Early Ordovician). A Precambrian–Cambrian assemblage has been identified at the base of Member 3 and the top of Member 2 in the Soltanieh Formation. The Soltanieh Formation consists of shallow marine sediments. Vertical microfacies variation reflects two regressive sequences, the earliest Cambrian System being a regressive cycle. The presence of Chuaria and Vendotaenia in the Soltanieh Formation allows correlation of Iranian sequences to those elsewhere in the world, indicating a late Neoproterozoic age. Detailed facies analyses of the Soltanieh, Barut, Zaigun, Lalun, and Mila formations allow refined palaeoenvironmental reconstructions to be made for the Ediacaran–Cambrian/Ordovician in Iran.

Abstract The ages of formations and larger groupings of Precambrian stratified rocks in the Cordillera are, in general, poorly constrained. Only two useful macrofossil assemblages are known: an Ediacaran, non-skeletal fauna found only in the youngest formations, and an older, Chuaria-Tawuia associationwhose duration of several hundred million years provides age control little more constrained than that provided by the few available radiometric dates. Stromatolite biostratigraphy to date has failed to provide useful chronocorrelation with the Riphean of the U.S.S.R. Only the youngest formations have been characterized palynologically. Few reliable radiometric dates have been published, but bracketing dates and structural relationships permit the assignment of most major successions of Cordilleran Proterozoic strata to one or other of the sequences recognized by G.M. Young and co-workers: Sequence A: =1.7 to =1.2 Ga Sequence B: =1.2 to =0.78 Ga Sequence C: =0.78 to =0.57 Ga These sequences, of which A and B are the subject of this chapter, provide a useful, though imprecise, framework for discussion. Sequence C nconformably overlies Sequence B and is discussed in Chapter 6. Sequence A (Purcell-Wernecke, Cap Mountain-Hornby Bay, Muskwa assemblages) conspicuously lacks the longitudinal Cordillera continuity of Upper Proterozoic strata (Sequence C) and is exemplified by the classical Purcell (Belt) Supergroup of southeastern British Columbia, southwestern Alberta, Montana and Idaho. Its patterns of sedimentary facies and thickness (up to 20 km) have generally been interpreted as those of a continental-marginsuccession, but for the Belt-Purcell Basin at least, work in the northwestern United