Migration of Entrepreneurs from Hong Kong: Background, Trendsand Impacts

This paper critically examines the movement of entrepreneurs from Hong Kong within the context of whether Chinese culture predisposes them to become entrepreneurs: that the type of business relations and networks that the Chinese employ is in some way distinct from those of other groups because of Confucianism and unique ‘Asian values’. This interpretation is found severely wanting. Entrepreneurs are seen to be but one type of migrant from China and Hong Kong, and there are significant differences within Chinese migrant groups. We need to move away from vague cultural explanations to consider the context in which migrant groups find themselves before a satisfactory analytical framework for ethnic entrepreneurship can be constructed. The case of entrepreneurs moving to Canada is taken to illustrate recent policy changes and the impact of entrepreneurs on destination economies.     

Origin of the Charnockites of the Louis Lake Batholith, Wind River Range, Wyoming

The 2·63 Ga Louis Lake batholith, a calc-alkalic plutonexposed in Wind River Range of western Wyoming, consists ofminor diorite, quartz diorite, granodiorite, and granite. Atshallow structural levels the batholith is pyroxene free, butat deeper levels, all units of the batholith contain pyroxenes.On its northern margin the batholith was emplaced at P = 5–6kbar, T = 775–800°C, fO₂ at FMQ (fayalite–magnetite–quartz)+ 1·5 to FMQ + 1·8, and aH₂O     

Sedimentology of subaqueous volcaniclastic sediment gravity flows in the Neogene Santa Maria Basin, California

Subaqueous tuff deposits within the lower Miocene Lospe Formation of the Santa Maria Basin, California, are up to 20 m thick and were deposited by high density turbidity flows after large volumes of ash were supplied to the basin and remobilized. Tuff units in the Lospe Formation include a lower lithofacies assemblage of planar bedded tuff that grades upward into massive tuff, which in turn is overlain by an upper lithofacies assemblage of alternating thin bedded, coarse grained tuff beds and tuffaceous mudstone. The planar bedded tuff ranges from 0.3 to 3 m thick and contains 1-8 cm thick beds that exhibit inverse grading, and low angle and planar laminations. The overlying massive tuff ranges from 1 to 10 m thick and includes large intraclasts of pumiceous tuff and stringers of pumice grains aligned parallel to bedding. The upper lithofacies assemblage of thin bedded tuff ranges from 0.4 to 3 m thick; individual beds are 6-30 cm thick and display planar laminae and dewatering structures. Pumice is generally concentrated in the upper halves of beds in the thin bedded tuff interval. The association of sedimentary structures combined with semi-quantitative analysis for dispersive and hydraulic equivalence of bubble-wall vitric shards and pumice grains reveals that particles in the planar bedded lithofacies are in dispersive, not settling, equivalence. This suggests deposition under dispersive pressures in a tractive flow. Grains in the overlying massive tuff are more closely in settling equivalence as opposed to dispersive equivalence, which suggests rapid deposition from a suspended sediment load. The set of lithofacies that comprises the lower lithofacies assemblage of each of the Lospe Formation tuff units is analogous to those of traction carpets and subsequent suspension sedimentation deposits often attributed to high density turbidity flows. Grain distributions in the upper thin bedded lithofacies do not reveal a clear relation for dispersive or settling equivalence. This information, together with the association of sedimentary features in the thin bedded lithofacies, including dewatering structures, suggests a combination of tractive and liquefied flows. Absence of evidence for elevated emplacement temperatures (e.g. eutaxitic texture or shattered crystàls) suggests emplacement of the Lospe Formation tuff deposits in a cold state closely following pyroclastic eruptions. The tuff deposits are not only a result of primary volcanic processes which supplied the detritus, but also of processes which involved remobilization of unconsolidated ash as subaqueous sediment gravity flows. These deposits provide an opportunity to study the sedimentation processes that may occur during subaqueous volcaniclastic flows and demonstrate similarities with existing models for sediment gravity flow processes.     

The formation and significance of irregularly shaped quartz grains in till

Thin sections and scanning electron microscopy of quartz sand grains from till show clearly that a number of grains have been modified in place. The irregular grains result from the action of circulating alkaline groundwater, episodically concentrated by evaporation on fracture surfaces within grains and on concave surfaces produced by fracture during glacial transport. Evaporation increases the pH of the pore water and localizes its effect in small pores with a high capillary potential. Subsequent dilution by rainwater or snow meltwater flushes the system so that evaporation can repeat the process again. Solution rounding in terrigenous sediments has a number of ramifications for any interpretation based on textural maturity of the sediment.     

Vertical gradational variability of fines deposited in a gravel framework

Vertical gradational structures develop as sand infiltrates into static gravel beds. Understanding the vertical distribution of interstitial sand deposits will improve predictions of ecological suitability and hyporheic hydrodynamics. A series of flume experiments was performed to investigate fine infiltration processes. Four sand distributions were introduced into flows over gravel beds. After each experiment, bed cores were extracted and analysed in vertical layers to examine the gradational trends with depth. Vertical trends of fine content were highly sensitive to the relative grain‐size distributions of the gravel bed and the introduced sand. For experiments with d_15gravel/d_85sand ratios 15·4 and larger unimpeded static percolation was observed, where sand filled the voids relatively uniformly from the bottom of the gravel layer to the top. Experiments with ratios 10·6 and smaller bridged. Sand clogged a thin layer of gravel pores near the bed surface, precluding subsequent infiltration. Interstitial sand deposits fined with depth of penetration for all experiments which was the result of three distinct but overlapping processes. (i) Granular sorting: As particles fell through the substrate, smaller material preferentially passed through the voids deeper into the gravel. (ii) Bed‐load sorting: Size segregation occurs in the wake of the leading bed form as smaller particles saltate further and settle first. (iii) Hydraulic sorting: Smaller sand was transported preferentially as suspended load filling the deep voids of the furthest flume positions downstream. Finally, when the experiments that formed a bridge layer were replicated with higher bed shear stresses, less interstitial sand deposition was observed. Higher shear stresses transported coarse particles downstream more efficiently causing bridge layers to form earlier and allowing less time for suspended load to settle into the deeper substrate pores before the pathways were closed.     

Amalgamated accumulations resulting from climatic and eustatic changes, Akchar Erg, Mauritania

The Akchar Erg of the Sahara of western Mauritania shows a morphology and stratigraphy that can be recognized as the amalgamation of late Pleistocene and Holocene deposits that reflect eustatic and climatic events. Mapping, trenching, and dating by ¹⁴C methods and artefacts show that the prominent complex linear dunes (draas) of the Akchar Erg are actually composite features showing at least three constructional and two destructional phases. The constructional phases are represented by three convex-up layers: (i) a modern veneer moulded into superimposed crescentic dunes, which partially mantle the larger linear bedforms; (ii) a middle, partly root-turbated sand deposited sometime during the last 4000 years; and (iii) a core of linear dune sand formed during the last glacial period (13 000–20 000 yr BP), which today shows relict relief, intense root-turbation, and pedogenesis. These constructional phases are separated by super bounding surfaces that coincide with erg destructional phases. Surface 2 bounds the middle aeolian sand, and is marked by a lag surface of small granules. Surface 1 is a very prominent surface with an abundance of Neolithic artefacts, and represents stabilization of the linear dunes during the humid, interglacial period (4000–11 000 yr BP). Interdraa deposits originated during the interglacial period, and consist of continental lacustrine limestones and sandstones, humic sands deposited in marshes, and sabkhas on the coast. The sabkhas originated during interglacial highstand of sea-level when interdraa areas were marine embayments, and subsequently dried during regression. The draa and interdraa sequences, therefore, in spite of being adjacent facies, actually represent different events and were not formed simultaneously. The upwind sand-sheet margin of the Akchar Erg shows exposures of the middle and core aeolian sands (which were previously protected from deflation by vegetation) being progressively cannibilized in the current phase of erg construction, and revealing a crystalline basement rock. In this proximal area, conditions are not favourable for the incorporation of these aeolian accumulations into the stratigraphic record.     

On the Stability of Sulfides, Oxides, and Native Metals in Serpentinite

Topologic relations indicate that the lowest relative oxygenfugacity attained in magnetite-bearing serpentinites occursin the presence of the assemblage serpentine-olivine-brucite.This is consistent with the observation that Ni-Fe alloys arepreferentially associated with this assemblage, both in progrademetaserpentinites, where the stable serpentine mineral is antigorite,and in retrograde serpentinites, where either antigorite, lizardite,or chrysotile may be present. The presence of the Ni-Fe alloyindicates that the assemblage serpentine-olivine-brucite-magnetitein prograde metaserpentinites equilibrated with an oxygen fugacityfour to five log units below the FMQ buffer whereas in retrogradeenvironments it equilibrated at oxygen fugacities as low assix or seven log units below FMQ. In carbonate-bearing metaperidotitesthe oxygen fugacity is buffered by the assemblage Fe-Mg carbonate-Feoxide and this buffering allows the oxygen fugacity to attainvalues above those of the HM buffer for rocks with relativelyhigh XCo2, such as those containing the assemblage talc magnesite.A considerable gradient in fO₂ may therefore be present acrossa serpentinite body from a partially serpentinized core to acarbonatized margin. This gradient is reflected in the compositionof the Fe and Ni sulfides. Sulfur-rich sulfides, such as milleriteor vaesite and pyrite, occur in carbonate-rich peridotites whilethe S-poor sulfide heazlewoodite is found in carbonate-freeserpentinites, and native Ni-Fe alloys, commonly without anyassociated sulfide, are preferentially found in the highly reduced,partially serpentinized peridotites. Under proper conditions the strong gradient info can lead tomobilization of metals or sulfides. Josephinite nodules, forexample, are postulated to have formed during high-temperature,reversible serpentinization. In such a situation, the locationof the serpentinization front and its associated environmentof extreme reduction will be thermally fixed, forming a sitefor deposition of native metals. The Ca in solution will bedeposited along with the metals as diopside and andradite, silicatescommon in josephinite. The tendency for sulfides in metaperidotiteto show evidence of mobilization in bodies metamorphosed toupper greenschist facies or higher may be explained by the factthat above 400 ?C the carbonate-bearing portion of an ultramaficbody may be associated with a fluid dominated by SO₂. Underthese conditions, sulfides may be dissolved and transportedto more-reducing areas of the body, such as the carbonate-freeserpentinite or the contact with the country rock, where theywould be reprecipitated.     

Petrology of the Caribou Mountain Pluton, Klamath Mountains, California

The Caribou Mountain pluton is a small trondhjemitic body thatintruded semipelitic schist of the Stuart Fork terrane in lateMiddle Jurassic to Early Cretaceous time. Its emplacement followedthe intrusion of an adjoining body of hornblende quartz dioritecalled the Middle Fork pluton and the mode of its emplacementwas as an asymmetric ballooning diapir (Davis, 1963), as shownby concentric foliation, radial late-stage dikes, foliated enclaves,and folded blocks of schlieren-banded tonalite. Coarse-grainedhornblende-bearing trondhjemite is the dominant rock type inthe Caribou Mountain pluton, and it is called the ‘maintrondhjemite’. It was followed by medium-grained ‘latetrondhjemite’ and by late-stage trondhjemitic and granodioriticdikes. All the trondhjemitic rock types are characterized bylow alkali contents, high light rare earth elements, low initial⁸⁷Sr/⁸⁶Sr, and low ¹⁸O. However, the late trondhjemite has higherNa₂O and a higher initial ⁸⁷Sr/⁸⁶Sr value than the main trondhjemite,and the two units cannot be related by fractional crystallization.The late granodioritic dikes are richer in Ba, Rb, Y, and Scthan the late trondhjemite and probably reflect assimilationof Stuart Fork metasedimentary rocks by late-stage trondhjemiticmagma. Mafic enclaves in the main trondhjemite contain xenocrysts ofquartz and plagioclase derived from the host by magma mixing.The enclaves have K₂O, Ba, and Rb contents similar to, or higherthan those of the host rocks. Their rare earth element (REE)patterns display strong middle REE enrichment caused by accumulationof hornblende, probably as the result of filter pressing. The main trondhjemite cannot be derived from Middle Fork magmabecause the initial ⁸⁷Sr/⁸⁶Sr of the Middle Fork pluton is lowerthan that of the trondhjemite. The absence of parental maficmagmas of appropriate composition suggests that the CaribouMountain trondhjemitic magmas formed by partial melting of anamphibolitic source rock compositionally similar to low-K tholeiite.     

TOPOGRAPHIC AND ISOSTATIC CORRECTIONS TO GRAVITY SURVEYS IN MOUNTAINOUS AREAS*

In mountainous areas it is an inadequate procedure to reduce gravity observations by merely subtracting the effect of an infinite flat slab of material between the station and sea-level, and adding a terrain correction. A programme is described which directly computes the effect of masses above sea-level, and mass-deficiencies below it; as well as the effect of compensating masses under the Pratt and Airy isostatic systems. As an example, the method has been applied to a regional gravity survey of Papua and New Guinea where it is seen to remove the usually high correlation of the Bouguer anomaly with local topography.