Spatial Distribution Pattern and Influencing Factors of Bed-and-breakfasts(B&Bs)from the Perspective of Urban-rural Differences:A Case Study of Jiaodong Peninsula,China

There are significant differences between urban and rural bed-and-breakfasts(B&Bs)in terms of customer positioning,economic strength and spatial carrier.Accurately identifying the differences in spatial characteristics and influencing factors of each type,is essential for creating urban and rural B&B agglomeration areas.This study used density-based spatial clustering of applications with noise(DBSCAN)and the multi-scale geographically weighted regression(MGWR)model to explore similarities and differences in the spatial distribution patterns and influencing factors for urban and rural B&Bs on the Jiaodong Peninsula of China from 2010 to 2022.The results showed that:1)both urban and rural B&Bs in Jiaodong Peninsula went through three stages:a slow start from 2010 to 2015,rapid development from 2015 to 2019,and hindered development from 2019 to 2022.However,urban B&Bs demonstrated a higher development speed and agglomeration intensity,leading to an increasingly evident trend of uneven development between the two sectors.2)The clustering scale of both urban and rural B&Bs continued to expand in terms of quantity and volume.Urban B&B clusters characterized by a limited number,but a higher likelihood of transitioning from low-level to high-level clusters.While the number of rural B&B clusters steadily increased over time,their clustering scale was comparatively lower than that of urban B&Bs,and they lacked the presence of high-level clustering.3)In terms of development direction,urban B&B clusters exhibited a relatively stable pattern and evolved into high-level clustering centers within the main urban areas.Conversely,rural B&Bs exhibited a more pronounced spatial diffusion effect,with clusters showing a trend of multi-center development along the coastline.4)Transport emerged as a common influencing factor for both urban and rural B&Bs,with the density of road network having the strongest explanatory power for their spatial distribution.In terms of differences,population agglomeration had a positive impact on the distribution of urban B&Bs and a negative effect on the distribution of rural B&Bs.Rural B&Bs clustering was more influenced by tourism resources compared with urban B&Bs,but increasing tourist stay duration remains an urgent issue to be addressed.The findings of this study could provide a more precise basis for government planning and management of urban and rural B&B agglomeration areas.

Gold mineralization in Jiaodong Peninsula and destruction of North China Craton:Insights from Mesozoic granite

Large-scale tectonic magmatism and extensive gold mineralization have occurred in the eastern North China Craton(NCC)(Jiaodong and Liaodong peninsulas)since Mesozoic,which indicated that the region experienced decratonization process.The genesis type of granites evolved from S-type to I-type and A-type during Late Jurassic to Early Cretaceous,and thus reflects the evolution of geodynamics in the Late Mesozoic,indicating the varied subduction process of the Paleo-Pacific Plate(PPP)and the craton destruction.The evolution of geochemical features shows that the mantle beneath the Jiaodong Peninsula evolved from EM-II in Jurassic to EM-I in Early Cretaceous,demonstrating that the mantle switched from enriched to depleted.The gold of decratonic gold deposits in Jiaodong Peninsula mainly comes from the lithospheric mantle domains metasomatized by fluids derived from the metamorphism and dehydration of the subducted slab in the mantle transition zone.The rapid decomposition of minerals leads to the concentrated release of ore-forming fluids,and this process leads to the explosive gold mineralization during the craton destruction.Extensive magmatic uplift and extensional structures,triggered by the craton destruction in Early Cretaceous formed the extensional tectonic system,providing space for the decratonic gold deposits in Jiaodong Peninsula.

Coupling Effects on Gold Mineralization of Deep and Shallow Structures in the Northwestern Jiaodong Peninsula, Eastern China

For understanding the possible deep-seated processes and geodynamic constrains on gold mineralization, comprehensive physicochemical and geochemical studies of gold mineralization have been undertaken within the paleo-lithosphere framework during the metailogenic epoch from the northwestern part of the Jiaodong Peninsula in this paper. A general image of the paleo-crust has been remained although it has been superimposed and reformed by post-metailogenic tectonic movements. The gold ore deposits occur usually in local uplifts and gradient belts featuring a turn from steep to gentle in granite-metamorphic contact zones, relative uplifts of gradient zones of the Curier isothermal interfaces, depressions of the Moho discontinuity and areas where depth contours are cut by isotherms perpendicularly. Gold mineralization and lithogenesis are characterized by high temperature, low pressure and high strength of thermal flux. The depth of mineralization ranges from 0.8 to 4.5 km. The depth of the top interface of the granitic complex in the metallogenic epoch is about 3 km. There is a low-velocity layer （LVL） at the bottom of the upper crust with a depth close to 19.5 km, which may be a detachment belt in the crust. The appearance of the LVL indicates the existence of paleo-hyperthermal fluid or relics of molten magma chambers, which reflects partial melting within the crust during the diagenetic and metallogenic epochs and the superposition effects of strike-slip shearing of the Taulu fault zone. The subsidence of the Moho is probably attributed to the coupling process of the NW-SE continental collision between North China and the Yangtze Block and the strike-slip movement of the Tanlu fault accompanied with underplating of mantle magma in the northwestern part of the Jiaodong Peninsula. The underplating of mantle magma may result in partial melting and make granite magma transfer upwards. This is favorable for the migration of metallogenic materials from deep to shallow to be enriched to form deposits. Coupling interactions between the strike-slip of the Taulu fault, the underplating of mantle magma, partial melting within the crust, and hyperthermal fluid, etc. may be the important factors controlling the gold mineralization and spatial structures in the metailogenic system.

A Study of Sr, Nd and O Isotopes of the K-rich Melanocratic Dykes in the Late Mesozoic Gold Field in the Jiaodong Peninsula

Geologic, petrographic and petrochemical studies of the late Mesozoic K-rich melanocratic dykes, including lamprophyres, andesite porphyrites and dacite-porphyry in the gold field system in the Jiaodong Peninsula, China, have shown that these dykes are characterized by rich potassium and alkali but poor titanium. They belong to an ultra-high potassic, shoshonitic and high potassic calc-alkaline rock series. The parental magma has relatively high initial strontium ratios ((87Sr/86Sr),=0.70895-0.71140) and low (143Nd/144Nd)1 ratios (varying from 0.51135 to 0.51231); and its δ18Osmow, whole rock values vary from +5.8%c to +10.6%c with a mean of +7.1%c. These features suggest that the source region of the magma is an enriched mantle wedge transformed from a continental lithosphere mantle which has experienced metasomatism by mantle-derived fluids with H2O-dominated fluids that were provided during the underthrusting of an ocean crust. The initial magma was generated by low-degree partial melting of the enriched mantle in its mature stage in the back-arc spreading environment. The evolution of magmas is associated with two trends, i.e., fractional crystallization and mixing with or intensive contamination by palaeo-crust materials or metamorphic rocks. The former process is evident in the gold field system of quartz-vein type, whereas the latter is dominated in the gold field system of the altered-rock type. This conclusion is very important for more detailed study of petrogenesis and mineralization through the crust-mantle interaction (exchange) in the Mesozoic in this region.

Geological and Fluid Inclusion Constraints on Gold Deposition Processes of the Dayingezhuang Gold Deposit, Jiaodong Peninsula, China

The Dayingezhuang gold deposit,hosted mainly by Late Jurassic granitoids on Jiaodong Peninsula in eastern China,contains an estimated 170 t of gold and is one of the largest deposits within the Zhaoping fracture zone.The orebodies consist of auriferous altered pyrite–sericite–quartz granites that show Jiaojia-type(i.e.,disseminated and veinlet)mineralization.Mineralization and alteration are structurally controlled by the NE-to NNE-striking Linglong detachment fault.The mineralization can be divided into four stages:(K-feldspar)–pyrite–sericite–quartz,quartz–gold–pyrite,quartz–gold–polymetallic sulfide,and quartz–carbonate,with the majority of the gold being produced in the second and third stages.Based on a combination of petrography,microthermometry,and laser Raman spectroscopy,three types of fluid inclusion were identified in the vein minerals:NaCl–H2 O(A-type),CO2–H2 O–NaCl(AC-type),and pure CO2(PC-type).Quartz crystals in veinlets that formed during the first stage contain mainly AC-type fluid inclusions,with rare PC-type inclusions.These fluid inclusions homogenize at temperatures of 251°C–403°C and have low salinities of 2.2–9.4 wt%NaCl equivalent.Quartz crystals that formed in the second and third stages contain all three types of fluid inclusions,with total homogenization temperatures of 216°C–339°C and salinities of 1.8–13.8 wt%NaCl equivalent for the second stage and homogenization temperatures of 195°C–321°C and salinities of 1.4–13.3 wt%NaCl equivalent for the third stage.In contrast,quartz crystals that formed in the fourth stage contains mainly A-type fluid inclusions,with minor occurrences of AC-type inclusions;these inclusions have homogenization temperatures of 106°C–287°C and salinities of 0.5–7.7 wt%NaCl equivalent.Gold in the ore-forming fluids may have changed from Au(HS)0 as the dominant species under acidic conditions and at relatively high temperatures and f O2 in the early stages,to Au(HS)2–under neutral-pH conditions at lower temperatures and f O2 in the later stages.The precipitation of gold and other metals is inferred to be caused by a combination of fluid immiscibility and water–rock interaction.

Study on the Metallogenetism of Sub-mantle Plume and Mantle Branches in the Gold Mineralization Concentration Area of Northwest Jiaodong Peninsula

The northwest of Jiaodong peninsula is characterized by its greatest gold concentration area, enormous gold reserves and limited time interval （115±5Ma） of gold mineralization in China. Studies show that the east area of north China began its mantle plume evolution since the Yanshanian movement, and the Laiyang sub-mantle plume and its surrounding mantle branches such as those in Guojiadian, Aishan and Panshidian were formed in the mineralization concentration area of northwestern Jiaodong peninsula. With the development of mantle plume →sub-mantle plume → mantle branch→ favorable expending structures, the deep-derived hydrothermal fluid moved up to the favorable places, such as brittle-ductile or ductile-brittle shearing zones, the internal and external contact zones of intrusions, dense fracturing zones and the contact zones between dikes and countryrocks, and concentrated into deposits. Then the gold mineralization concentration zones that are centralized on mantle branches were formed. This study takes Guojiadian mantle branch as an example to discuss their metallogenetism and conclude the metallogenetic mode.

Geology and mineralization of the Sanshandao supergiant gold deposit(1200 t)in the Jiaodong Peninsula,China:A review

The Jiaodong Peninsula in Shandong Province,China is the world’s third-largest gold metallogenic area,with cumulative proven gold resources exceeding 5000 t.Over the past few years,breakthroughs have been made in deep prospecting at a depth of 500‒2000 m,particularly in the Sanshandao area where a huge deep gold orebody was identified.Based on previous studies and the latest prospecting progress achieved by the project team of this study,the following results are summarized.(1)3D geological modeling results based on deep drilling core data reveal that the Sanshandao gold orefield,which was previously considered to consist of several independent deposits,is a supergiant deposit with gold resources of more than 1200 t(including 470 t under the sea area).The length of the major orebody is nearly 8 km,with a greatest depth of 2312 m below sea level and a maximum length of more than 3 km along their dip direction.(2)Thick gold orebodies in the Sanshandao gold deposit mainly occur in the specific sections of the ore-controlling fault where the fault plane changes from steeply to gently inclined,forming a stepped metallogenic model from shallow to deep level.The reason for this strong structural control on mineralization forms is that when ore-forming fluids migrated along faults,the pressure of fluids greatly fluctuated in fault sections where the fault dip angle changed.Since the solubility of gold in the ore-forming fluid is sensitive to fluid pressure,these sections along the fault plane serve as the target areas for deep prospecting.(3)Thermal uplifting-extensional structures provide thermodynamic conditions,migration pathways,and deposition spaces for gold mineralization.Meanwhile,the changes in mantle properties induced the transformation of the geochemical properties of the lower crust and magmatic rocks.This further led to the reactivation of ore-forming elements,which provided rich materials for gold mineralization.(4)It can be concluded from previous research results that the gold mineralization in the Jiaodong gold deposits occurred at about 120 Ma,which was superimposed by nonferrous metals mineralization at 118‒111 Ma.The fluids were dominated by primary mantle water or magmatic water.Metamorphic water occurred in the early stage of the gold mineralization,while the fluid composition was dominated by meteoric water in the late stage.The S,Pb,and Sr isotopic compositions of the ores are similar to those of ore-hosting rocks,indicating that the ore-forming materials mainly derive from crustal materials,with the minor addition of mantle-derived materials.The gold deposits in the Jiaodong Peninsula were formed in an extensional tectonic environment during the transformation of the physical and chemical properties of the lithospheric mantle,which is different from typical orogenic gold deposits.Thus,it is proposed that they are named“Jiaodong-type”gold deposits.

Deciphering anomalous Ag enrichment recorded by galena in Dayingezhuang Au(-Ag)deposit,Jiaodong Peninsula,Eastern China

Texture,geochemistry,and in-situ Pb isotope of galena were investigated to probe the origin of anomalous Ag enrichment in the Dayingezhuang Au(-Ag)deposit.Silver enrichment postdates the main Au mineralization and occurs in the south of the Dayingezhuang deposit.It is primarily associated with galena and the exsolution of Ag-rich sulfosalts(e.g.,matildite)in distal vein-ores related to steeply dipping brittle fractures.Silver-rich galena is characterized by the least radiogenic Pb isotope signature(^(206)Pb/^(204)Pb 17.195–17.258 and ^(208)Pb/^(204)Pb 37.706–37.793),possibly indicating a metasomatized lithospheric mantle or modified lower crustal source for Pb and Ag.Both of these mafic and ultramafic source regions have been previously suggested as Au reservoirs for other Jiaodong Au deposits,implying that the metal reservoir has only a weak control on the uneven Ag-enrichment.Since the Ag-enrichment areas are located in the footwalls of both the Dayingezhuang and Zhaoping faults,the enrichment was most likely dominated by local rotational stress during coeval movements of the two faults in a NE–SW compression and NW−SE extension regime.This work highlights the shallow-crust structural deformation responsible for controlling the flow of late ore-forming fluid resulting in local anomalous metal enrichment.

Emplacement Depths and Exhumation of Mesozoic Granitoids Responding to Lithospheric Destruction in the Jiaodong Peninsula, North China Craton

1 Introduction The North China Craton(NCC)has experienced lithospheric destruction in Mesozoic accompanied with crustal exhumation.Fission track or(U-Th)/He dating of zircon and apatite for the Mesozoic granitoids in the

Cooling History of Mesozoic Magmatism and Implications for Large-Scale Gold Mineralization in the Jiaodong Peninsula, East China: Constraints from T-t Paths Determined by U-Pb Thermochronology of Zircon and Apatite

The Mesozoic intrusions of the Jiaodong Peninsula,eastern China,host giant gold deposits.Understanding the genesis of these deposits requires the determination of the source of the parental auriferous fluid and the timing of gold mineralization,which are strongly influenced by the cooling/uplift histories of the hosting intrusions.We performed an integrated U-Pb geochronology study on both zircon and apatite from four major magmatic episodes of the Jiaodong Peninsula.The zircon and apatite U-Pb ages are 156.9±1.2 and 137.2±2.4 Ma for the Linglong intrusion,129.9±1.0 and 125.0±3.8 Ma for the Qujia intrusion,119.5±0.7 and 117.2±1.8 Ma for the Liulinzhuang intrusion,118.6±1.0 and 111.6±1.6 Ma for the Nansu intrusion,respectively.The coupled zircon and apatite data of these granitoids indicate a slow cooling rate(11.9°C/Ma)in the Late Jurassic,and rapid uplift and cooling(35.8-29.2°C/Ma)in the Early Cretaceous.The dramatically increased uplift and cooling period in the Early Cretaceous are contemporaneous with large-scale gold mineralization in the Jiaodong Peninsula.This implies that thermal upwelling of asthenosphere and related tectonic extension played an important role in gold remobilization and precipitation.

Large clusters of gold deposits and large-scale metallogenesis in the Jiaodong Peninsula, Eastern China

The Jiaodong Peninsula is the largest repository of gold in China based on the production in history. It covers less than 0.2% of China's territory, but production of gold accounts for about one fourth of the whole country. Thus, the Jiaodong Peninsula is a typical area or case of large-scale metallogenesis and a large clusters of mineral deposits in China. It is characterized by the large clusters of gold deposits in large scale, high reserve and short mineralizing stage. In this study, we suggest that the eastern boundary of the large clusters of gold deposits is as same as that of North China Block, the gold deposits are hosted by Archean metamorphic rocks or Mesozoic granites, and the age of gold mineralization is 121.6 to 122.7 Ma. Gold and related ore-forming materials are derived from multisources, i.e. Archean metamorphic rocks, granites and intermediate-mafic dikes, especially, intermediate-mafic dikes and calc-alkaline granites. The metallogenic geodynamic process is constrained by the tectonic evolution of eastern North China Block during Late Mesozoic, and it is the result of the interaction between mantle and crust as the boundary plates are playing role on the block.

Petrology,Geochemistry,and Sr-Nd-S Isotopic Compositions of the Ore-Hosting Biotite Monzodiorite in the Luanjiahe Gold Deposit,Jiaodong Peninsula,China

The Jiaodong Peninsula is one of the most important Au ore provinces in China.There is an ongoing debate on the correlation between ore formation and magmatism in this province,because few intrusive rocks exhibit a clear association with ore deposits.A mineralized biotite monzodiorite(BM)stock,with disseminated ore,pervasive phyllic alteration,and no deformation,was found in a borehole in the footwall of the Zhaoping fault within the Luanjiahe Au deposit,which may shed light on this debate.The biotite monzodiorite contains explosion breccias,miarolitic cavities,skeletal and den-dritic quartz,and late-stage evolved aplite dikes,and the in-situδ34S values of the disseminated pyrite which is associated with Au mineralization are-1.7‰ to 7.3‰(mean=3.5‰),indicative of a magmatic-hydrothermal system.These findings,combined with the reported age of 123 Ma,show that the intru-sion has close spatial,temporal,and geochemical relationships with Au mineralization in the area.The biotite monzodiorite is metaluminous,high-K calc-alkaline and shoshonitic,with enrichment in light rare earth elements(REEs)and large-ion lithophile elements(LILEs),depletion in high-field-strength elements(HFSEs),and enriched Sr-Nd isotopic compositions.The intrusion may be the product of par-tial melting of enriched lithospheric mantle with a small lower crustal component.The hydrous,Au-bearing,enriched mantle source,and the strongly oxidized magma that was generated,created fa-vorable conditions for Au mineralization.

Mineralogical Characteristics and in-situ Sulfur Isotopic Analysis of Gold-Bearing Sulfides from the Qilishan Gold Deposit in the Jiaodong Peninsula,China

Large-scale gold mineralization during the Early Cretaceous is identified in the Jiao-dong Peninsula of China.Sources of ore-forming fluids remain debated.We study the Qilishan gold deposit in the northwestern Jiaodong Peninsula with detailed mineralogical observation and in-situ sulfur isotope analyses,in order to reveal the gold occurrence and the origin of ore-forming fluids.The Qilishan gold deposit is mainly clastic altered rock-type in mineralization,and ore minerals are visible native gold,electrum,pyrite,chalcopyrite and galena,gangue minerals as quartz,sericite and calcite.The gold occurrence includes inclusion and intergranular types,formed within pyrites and chalcopy-rites and along their fissures.In-situ sulfur isotope analysis of gold-bearing sulfides suggests that the Qilishan deposit is enriched in heavy sulfur,withδ34S values mainly from+8.0‰to+12.0‰.δ34S val-ues increase gradually with the fluid evolution from the early to late stages,which is interpreted to be related to the loss of sulfur via sulfide precipitation.The crystallization of sulfides from hydrothermal fluids may have triggered the instability of Au(HS)2,and finally led to gold precipitation.Combined with sulfur isotope compositions of other gold deposits(n=43)and wall-rocks in the Jiaodong Peninsu-la,it is proposed that the ore-forming fluids were probably not directly originated from metamorphic wall-rocks(e.g.,Jiaodong Group).Moreover,the relatively long time interval rules out the possibility that the gold mineralization(ca.120 Ma)was associated with granitic magma activities(mostly 160-150 Ma).Possible ore genesis scenario is that,long-term subduction of slabs(e.g.,the Paleo-Pacific)with gold-enriched pyritic materials and crustal sedimentary rocks resulted in both high Au contents and positiveδ34S values of sulfur in the lithospheric mantle below the North China Craton.Subse-quently,devolatilization of the metasomatized mantle produced auriferous fluids that migrated up-ward along translithospheric fault systems,and gold finally precipitated in favorable structural posi-tions,generating the world-class Jiaodong deposits in the Early Cretaceous.

Structure, evolution and regional tectonic implications of the Queshan metamorphic core complex in eastern Jiaodong Peninsula of China

The Queshan MCC is an important example of a crustal extensional structure in the eastern Jiaodong Peninsula along the southeastern margin of the NCC in the Early Cretaceous. The MCC is a typical Cordilleran-type core complex with a three-layered structure:(1) the upper plate is constituted by the Cretaceous supradetachment basin and Paleoproterozoic basement;(2) the lower plate comprises the Neoarchean high-grade metamorphic complexes and late Mesozoic granitic intrusions; and(3) the two plates are separated by a master detachment fault. A series of late NEN-oriented brittle faults superimposed on and destructed the early MCC. Petrology, geometry, kinematics, macro- and micro-structures and quartz c-axis fabrics imply that the MCC has a progressive exhumation history from middle-lower to subsurface level(via middle-upper crustal level) under the nearly WNW-ESE regional extensional regime. We present structural and geochronological evidence to constrain the exhumation of the Queshan MCC from ca. 135 to 113 Ma. Based on the comprehensive analysis of the different patterns of extensional structures in the Jiaodong and Liaodong Peninsula, we have defined the Jiao-Liao Early Cretaceou extensional province and further divided the crustal extension of it into two stages: the first stage was the intense flow of the middle-lower crust and the second stage was the extension of the middle-upper crust. Combining the tectonic setting, the lithosphere thinning in the Jiao-Liao Early Cretaceous extensional province can be considered a typical model for the response of crust-mantle detachment faulting under regional extension in East Asia.

Two Super-Large Gold Deposits Have Been Discovered in Jiaodong Peninsula of China

During 2015, gold prospecting in Laizhou City of Shandong Peninsula in China has achieved a major breakthrough. Deposits containing 470 and 389 tons of gold metal were discovered in the northern sea area of Sanshandao and the Shaling area, respectively. As a result, the gold prospective resources in the entire Jiaodong Peninsula have now exceeded 4000 tons, fully indicative of the super-large prospecting potential of the Jiaojia-type deposits.

Genesis of High Ba-Sr Yashan Intrusion from the Jiaodong Peninsula,Eastern China:Implications for the Destruction of the North China Craton

The origin of the Mesozoic high Ba-Sr(HBS)granitic magmatism in the Jiaodong Peninsula remains controversial in petrogenesis models and geodynamic settings.Here,we report zircon UPb age,trace element and oxygen isotope compositions,and whole-rock major-trace element and Sr-Nd isotope compositions of the HBS Yashan granodiorite.The zircon U-Pb age of~118 Ma denotes that the Yashan granodiorite belongs to the Weideshan-stage magmatic activity,which is consistent with the age of Mo mineralization in the Yashan intrusion.The low Sr/Y(48.8-115)and high(La/Yb)_(N)(23.8-50.4)ratios of the Yashan granodiorite are analogous to adakitic features derived from the lower-crust.This is also supported by the whole-rock initial^(87)Sr/^(86)Sr ratios(0.7096-0.7103)and zircon δ^(18) O values(6.79‰-8.03‰).Contemporaneous mantle-derived mafic microgranular enclaves indicate the involvement of the metasomatized lithospheric mantle.The high magma oxygen fugacity of the Yashan intrusion as indicated by high zircon Ce^(4+)/Ce^(3+) values suggests the involvement of plate subduction.The obviously lower Dy/Yb,La/Yb and Sr/Y ratios of magmatic rocks in the Weideshan-stage than those in the early-stage imply lithospheric thinning of the eastern North China Craton.We propose that the Yashan HBS granodiorite was formed by crust-mantle interactions during slab rollback.

Study of thrust and nappe tectonics in the eastern Jiaodong Peninsula, China

Thrust and nappe tectonics have affected the eastern Jiaodong Peninsula, the easternmost terminal of the Sulu Ultra-high Pressure Metamorphic Belt. Four nappes have been mapped, named respectively the Shidao, Rongcheng, Mishan and Mouping nappes. The methods used included multi-scale struc- tural analysis and structural chronology analysis. These nappes define four deep level slip-thrust shear zones that were mainly active in the Mesozoic. The amount of ductile deformation decreases from the Shidao to Rongcheng to Mouping to Mishan shear zones, and shows an inverse relationship with temperature. 40Ar/39Ar chronological analysis and the chronological results of former workers reveal four movement steps defined by the development of thrusts and nappes in the late Triassic (210-180 Ma), extensional movement from the Jurassic to early Cretaceous (180-130 Ma), slip-thrust movement in the Early Cretaceous (130-120 Ma), and extensional movement since the Late Cretaceous (120 Ma). The order of boundary shear zone motion in the period of slip-thrust movement during the Early Cre- taceous (130-120 Ma) was along the Shidao, Rongcheng, Mouping and finally the Mishan shear zone. This resulted in clockwise rotation of the nappes relative to block west to the Tan-Lu Faults. Because of the similar evolutionary history of the Tan-Lu Faults and the thrust and nappe structure in the eastern Jiaodong Peninsula, slip dislocation along the Tan-Lu Faults might have been absorbed by thrust and nappe tectonics in the Jiaodong area in the Mesozoic era, resulting in much less dislocation on the Tan-Lu faults in North Eastern China than that in south along the Jiaodong Peninsula.

Tectono-chronologic constraints on a Mesozoic slip and thrust belt in the eastern Jiaodong Peninsula

A major slip and thrust belt within the eastern Jiaodong Peninsula is located at the eastern terminal of the Qinling-Dabie-Sulu orogenic belt between the Sino-Korea Block and Yangtze Block. Although a lot of isotope chronologic data have been obtained regionally, little structural chronological research has been conducted in this region and this paper corrects that. Syn-deformational minerals were system-atically selected from samples of the NE-ENE trending transpressional shear zones and transpres-sional nappes and carefully analysed using 40Ar/39Ar methods. Two tectonic events were defined with the first event resulting from early movement of transpressional nappes around 190 Ma ago. This ac-cords with the period of syn-orogenic sinistral slip of the Tan-Lu faults and clockwise shear in the Eastern Qinling-Tongbaishan part of the Qinling-Dabie-Sulu orogenic belt. The second event involved strikeslip thrust movement of deep shear zones between 130Ma and 120Ma. This resulted from the onset of Mesozoic tectonic conversion in the eastern Jiaodong Peninsula. The sinistral strikeslip-thrusting in Jiaodong Peninsula and the extensional tectonism (toward ESE) in Liaodong Peninsula probably resulted in the clockwise rotation of Korea Peninsula in late Mesozoic.

胶西北金矿控矿断裂深部特征及对找矿的启示——来自地球物理探测的证据

[研究目的]胶东是全球著名的金成矿区,金矿床主要受断裂构造控制,该区尚有很多断裂是无矿的,以往对断裂的深部形态及赋矿断裂与无矿断裂的区别特征缺乏深入研究。[研究方法]本文通过在胶东西北部实施重、磁、电长剖面和穿越主要金矿集区的广域电磁剖面、反射地震剖面,揭示了断裂深部特征,为赋矿断裂和无矿断裂的识别提供了重要证据。[研究结果]地球物理探测表明,胶西北地区的断裂构造有陡倾角的深断裂、缓倾角的铲式断裂和陡倾角的小断裂,其中控矿的三山岛、焦家和招平断裂均是铲式断裂。结合对金矿床的研究发现,矿床主要赋存于缓倾角断裂中,矿体呈阶梯分布特征,陡倾角的深断裂中未见明显的金矿化蚀变,现今金矿床赋存的最大深度在5 km左右。[结论]综合分析认为,低角度拆离断层和连续性不好的高角度小断层有较好的物理圈闭条件,有利于矿化富集;而产状平直、陡倾的深断裂不具备物理圈闭的条件,不利于成矿。胶东型金矿的找矿方向应集中于缓倾角的铲式断裂及其派生、伴生的陡倾角小断裂附近。

胶东西岭金矿床黄铁矿热电性特征及深部找矿意义

西岭金矿床位于三山岛金矿床东侧,是当前胶东金矿集区内新发现的单一矿体规模最大、埋藏最深的金矿床。在地质观察的基础上,开展了不同深度的黄铁矿热电性特征研究。结果表明:西岭金矿床黄铁矿热电系数离散范围和离散度整体较大且相对稳定;浅部黄铁矿热电导型均为N型,而深部均为P型;成矿温度主要集中在250~360℃之间,属中—高温热液型金矿床;计算得出黄铁矿热电导型变化梯度值较小,并估算出矿体剥蚀率约为75%。综合黄铁矿各类热电性特征参数,认为西岭金矿床深部仍有较大的找矿前景,矿体最大埋深可达-3000 m标高。已知金矿体具有向NE侧伏的规律,认为沿着NE侧伏方向至-3000 m标高处是有效的深部找矿靶区位置。西岭金矿床黄铁矿热电性特征研究可为胶东地区金矿床的深部找矿预测提供科学依据。