The apparent randomness in patterns of earthquake activity are modeled using a quasi-static, truss-fault block analogy of earthquake occurrence. The earthquake belt is modeled utilizing a series of fault blocks along a seismic belt can experience either enhanced or suppressed seismic activity immediately after and during the years that follow a modeled earthquake. However, the regions that adjoin the block which has experienced a modeled earthquake, are primarily affected by the enhancing or the suppressive effected of a modeled earthquake. Seismic gaps are attributed to the complex interaction between fault blocks and the manner in which modeled earthquakes redistribute forces to an elastic truss, which represents the oceanic lithosphere. Due to the enhancing and suppressive seismic effects, seismic gaps within the model are filled by earthquakes that occur in a different order from one modeled earthquake to another. Thus the truss-fault block model produces a semi-random pattern of earthquake occurrence, although there are similarities between modeled earthquake cycles. Model behavior is not unlike the space-time distribution patterns observed in nature. Owing to the semi-random character of the model, the recurrence interval within each fault block is different and the recurrence interval changes from cycle to cycle. Also the recurrence interval increases if a fault block is interrupted by the suppressive effects of earthquakes in adjacent areas. / Earth and Environmental Science

Application of the PAC hypothesis to the Olney and Elmwood Members of the Manlius Formation in central New York supports the general hypothesis that this portion of the Helderberg Group accumulated episodically. This limited stratigraphic interval consists of small-scale upward­ shallowing cycles (PACs) which strongly resemble well­documented ancient and Recent upward-shallowing tidal cycles. PACs of the Olney and Elmwood Members constitute a shallowing PAC sequence which developed as a result of eastward prograd­ation of tidal facies. Within this shallowing PAC sequence, paleoenvironments and paleogeography evolved episodically in response to widespread punctuation events at PAC boundaries. Within each PAC of the sequence, paleoenvironments developed gradually as a result of sedimentary aggradation; between PACs paleogeographic patterns were abruptly altered by punctuation events. / Earth and Environmental Science / Accompanied by one .pdf file: 1) Lee-Supplemental-1981.pdf

Northerly dipping compositional layering in the central and western portions of the Stillwater Igneous Complex, the moderate northward slope of the Beartooth Front north of these outcrops, as well as gravity data (Bonini, 1981) provide structural evidence for the continuation at depth of the Complex north of the middle Cambrian unconformity along its northern boundary. The Lodgepole, Enos Mountain and Susie Peak plutons represent multiple intrusions of intermediate magmas at emplacement depths ranging from 2 km to near-surface conditions during late Cretaceous time. These intrusions lie respectively 8, 9, and 12 km north of the nearest outcrops of the Stillwater Complex. The Lodgepole Intrusion consists of an early dacite phase and a later diorite phase, the latter containing abundant xenoliths (up to 31 cm in diameter) in the area north of Clover Basin near its western margin. These xenoliths include foliated mafic amphibolites, gneisses, Paleozoic sediments, and cumulate textured basic rocks. Smaller xenoliths of similar lithologies are found in the Enos Mountain and Susie Peak intrusions. The cumulate textured xenoliths have magmatic textures, basic silica contents, and tholeiitic normative rnineralogies. The euhedral to subhedral, medium to coarse grained, tabular plagioclase in the xenolith sample suite has a total span of An62 to An86 (mole %) with variability in a single sample generally 1 to 5 mole % An. Minor primary-appearing augite is found in anorthositic specimens, but most of the primary mafic minerals have been altered to calcic amphibole and chlorite. The external habit and mineralogy of some mafic mineral domains suggest that they are pseudomorphic after primary pyroxenes and olivine. Based on interpretation of mineralogy and texture, cumulate xenoliths were classified as anorthosites, gabbros, norites, gabbronorites, troctolites, and altered ultramafic lithologies. One xenolith contained chromite, one contained graphite, and a few contained minor Fe and Cu sulfides. Mineral compositions and textures lead this author to conclude that the xenoliths were brought up from the underlying Stillwater Complex. Based on estimate of the fluid properties of the andesitic magma above its liquidus, ascent rates of greater than 1.7 m/second were needed to have raised the cumulate xenoliths. The lack of xenoliths with plagioclase compositions <An62, as well as structural space constraints imposed by the existence of non-cumulate basement lithologies north of the East Boulder Fault lead this author to question the existence of the thick differentiated Hidden Zone postulated by Hess (1960). / Earth and Environmental Science / Accompanied by two .pdf files: 1) Brozdowski-Supplemental1-1983.pdf 2) Brozdowski-Supplemental2-1983.pdf

Oxygen, iron, magnesium, and carbon are the principal geochemical parameters employed to elucidate the chemical relationship between the Bushveld Merensky Reef and associated structures termed "potholes". Potholes are large (hundreds of meters wide and tens of meters deep) depressions in the footwall filled with Merensky equivalent materials. Three potholes were analyzed in this study. The concentration of inorganic carbon was found to range from 1,835 ppm to 131 ppm. The fO2 analyses at 1150 C have a range from 10^-11.9 to 10^-13.9 atmospheres. In particular, stratigraphically equivalent basal chromites show a decrease from 10^-12.1 in the Normal Merensky Reef to 10^-13.9 in the pothole bottom. The ratios of Total Fe (as FeO/MgO + Total Fe (as FeO)) in these basal chromites show a range of 0.779 to 0.839 from pothole bottom to Normal Merensky Reef, respectively. Finally, Fe^+3 concentration in basal chromites, relative to Fe^+2 concentration, shows a depletion in the bottom of potholes. Parameter analyses indicate that geochemical gradients not only exist along stratigraphically equivalent horizons (lateral gradients) but also exist along stratigrpahic units (vertical gradients). Various hypotheses which address the genesis of pothole formation are reviewed in light of the above mentioned gradients. The author has found that the plutonic fumarole hypothesis as proposed in Ulmer et al. (1981) is best suited to explain the lateral and vertical geochemical gradients. Potholes acting as plutonic fumaroles releasing reducing carbonaceous and/or sulfurous gases are discussed as a possible mechanism for Merensky Reef petrogenesis. The author's geochemical data and published research from the literature are integrated into a discussion of new ideas for the platinum-reef petrogenesis in the Bushveld Complex. / Earth and Environmental Science / Accompanied by one .pdf file: 1) Buntin-Supplemental-1983.pdf

Application of the PAC Hypothesis (Goodwin and Anderson, 1981) to shallow shelf facies containing the Dicoelosia Zone (Rickard, 1962) in the Lower Devonian Kalkberg Formation, reveals the presence of three PACs that are correlated throughout the Hudson Valley. Microfacies and paleoenvironmental analysis demonstrates that, in vertical succession, each of these PACs was deposited in a successively deeper environment of deposition. This eposodic deepening is interpreted to have occurred as a result of a sequence of two minor punctuation events and two major punctuation events. A comparison of the stratigraphic position of the Dicoelosia epibole with PACs shows the epibole to occur in two successive PACs at different locali­ties, and therefore not to be an accurate time-stratigraphic unit. The first and lower PAC contains Dicoelosia only at the basin axis near Catskill. The PAC immediately above the first PAC contains Dicoelosia only at the areas flanking the basin axis to the north and south and not at the basin axis. Therefore, since the occurrence of Dicoelosia is laterally discontinuous in both PACs, the Dicoelosia epibole does not exist as a chronostratigraphic horizon of Dicoelosia abundance. / Earth and Environmental Science / Accompanied by one .pdf file: 1) Connor-Supplemental-1983.pdf

Application of the Hypothesis of Punctuated Aggradational Cycles to the stratigraphic analysis of the Binnewater Sandstone in southeast­ern New York reveals that the formation was deposited as a sequence of PACs (thin shallowing-upward cycles) in response to a series of six small-scale transgressive episodes. Each successive transgression ex­tended farther to the northeast resulting in an onlapping sequence which is conformable with the High Falls Formation to the southwest and unconformable with the Ordovician Normanskill Formation to the northeast. Within the study area the Binnewater Sandstone sequence is unconforma­bly overlain by the Rondout Formation. At each locality the Binnewater Sandstone consists of PACs repres­enting nearshore, shallow subtidal to high intertidal elastic paleo­environments. These PACs are laterally traceable and can be correlated amongst localities. To the southwest at High Falls the sequence consists of six PACs; to the northeast at South Wilbur the sequence is much thinner because only the third and fourth PACs in the sequence were deposited and preserved. That is, deposition did not begin in the northeast until the area was inundated by the third transgressive event. Then, following deposition of PACs 4, 5 and 6, the sequence was differentially truncated by erosion which eliminated PACs 5 and 6 at Wilbur. Following erosion of the Binnewater sequence the resulting erosional surface was flooded throughout the area by the first Rondout trangressive event indicating the near horizontality of this surface. These detailed strat­igraphic relationships of the Binnewater Sandstone between High Falls and Wilbur can be explained either by differential subsidence of a few meters accompanied by a minor sea-level fall or by differential uplift of a few meters causing greater erosion to the northeast. / Earth and Environmental Science

The facies mosaic within the Thacher Member of the Manlius Forma­tion in central New York State can be subdivided into a sequence of ten upward-shallowing carbonate units. Each unit or Punctuated Aggradational Cycle (PAC), is bounded by non-depositional transgressive (deepening) surfaces. Between these surfaces, basal subtidal facies grade upward into shallow subtidal, intertidal and/or supratidal facies. These PACs exhibit facies which were deposited in several environments including an open shelf, a subtidal stromatoporoid patch reef, a restricted shelf, a bioclastic sand shoal and sand shoal fringe, and gradational shallow subtidal environments into intertidal and supratidal flat environments. Each PAC can be correlated between closely spaced outcrops by tracing key beds, facies lithosomes, cycles of similar thickness and internal facies arrangement. Longer distance correlation across the study area can be accomplished by matching shallowing sequences of PACs, matching major vertical facies changes across transgressive surfaces (indicating major deepening events) and by matching laterally persistent facies lithosomes. Analysis of the facies mosaic within a PAC provides a detailed interpretation of the paleogeographic changes accompanying its deposition. The Thacher Member consists of a sequence of ten paleo­environmental units consisting of facies which exhibit gradational transitions within and distinct facies changes at their boundaries. / Earth and Environmental Science / Accompanied by one .pdf file: 1) Rush-Supplemental-1984.pdf

In the Hudson Valley region the Thacher Member of the Manlius Formation consists entirely of PACs, thin shallowing­ upward cycles separated by correlative sharp non-depositional surfaces. Vertically, within each PAC, facies represent aggradational shallowing; laterally adjacent facies in each PAC represent contiguous paleoenvironments. Between PACs facies change abruptly at PAC boundaries in response to rapid episodic base-level rises. This small-scale stratigraphic framework permits detailed paleoenvironmental analysis of specific facies with respect to depth and lateral position relative to other facies. In this analysis, the Manlius Formation consists of 11 PACs each of which contains variable but coeval subtidal facies in its lower portion and intertidal or supratidal facies in the upper portion. In previous studies (e.g. Laporte, 1967), the assumption of a gradualistic model of stratigraphic accumulation resulted in the conclusion that the Manlius Formation comprised a disordered facies mosaic in which any facies could occur at any time. In contrast, this analysis, which assumes episodic stratigraphic accumulation at a small scale, has produced a highly ordered interpretation. Specifically, the PAC approach indicates that facies patterns were controlled by abrupt allogenic events (base-level rises) followed by sedimentary aggradation resulting in a series of correlative PACs containing predictable facies patterns. / Earth and Environmental Science / Accompanied by one .pdf file: 1) Saraka-Supplemental-1984.pdf

Composite ultramafic xenoliths were collected at Peridot Mesa, San Carlos, Arizona. These nodules were analyzed petrographically, by electron microprobe, and for intrinsic oxygen fugacity (IOF). Textures proved to be transitional between those of igneous and those of metamorphic petrogenetic environments. Phase chemistry interpretations were not totally consistent with either igneous or metamorphic models of formation. IOF data could not be used to unravel equilibrium relationships between solid phases, but were overprinted by reactions with volatiles contained in the minerals, chiefly CO2. These results indicate that the nodules were derived from a complex upper-mantle source region characterized by multi-phase igneous events with important intervening, probably sub-solidus, i.e. metamorphic, reactions between phases. / Earth and Environmental Science / Accompanied by one .pdf file: 1) Weiss-Supplemental-1984.pdf

Application of the PAC hypothesis to the Thacher Member of the Manlius Formation has resulted in its di­vision into eleven correlative PACs, shallowing-upward cycles produced by sedimentary aggradation following rap­id episodic base-level rises. The eleven Thacher PACs are organized into two sequence so Manlius PACs 1-5 contain predominantly intertidal facies; Manlius PACs 6-11 are comprised mainly of subtidal and supratidal facies. These sequences are discernible at all locali­ties in the Hudson Valley and central New York State. This study demonstrates that certain distinctive facies found in PACs of the upper Thacher sequence de­veloped laterally persistent horizons, an observation made earlier by Rickard (1962), The PAC 8 algal laminite horizon, which corresponds to the waterlime datum of Rickard (1962, figure 2), provides the primary time and environmental datum for the upper Thacher PAC sequence. Correlation of upper Thacher PACs demonstrates that the Manlius-Coeymans formational contact is unconformable. in eastern New York State. The thickness of section and number of PACs in the upper Thacher decreases progressively from west to east. Erosion responsible for the missing section and PACs is attributed to differential tectonic uplift of the eastern basin margin prior to any Coeymans deposition. / Earth and Environmental Science / Accompanied by one .pdf file: 1) Goodman-Supplemental-1985.pdf