Structural, metamorphic and geochronological relations between the Zanskar Shear Zone and the Miyar Shear Zone (NW Indian Himalaya): Evidence for two distinct tectonic structures and implications for the evolution of the High Himalayan Crystalline of Zanskar

The geologic structures and metamorphic zonation of the northwestern Indian Himalaya contrast significantly with those in the central and eastern parts of the range, where the high-grade metamorphic rocks of the High Himalayan Crystalline (HHC) thrust southward over the weakly metamorphosed sediments of the Lesser Himalaya along the Main Central Thrust (MCT). Indeed, the hanging wall of the MCT in the NW Himalaya mainly consists of the greenschist facies metasediments of the Chamba zone, whereas HHC high-grade rocks are exposed more internally in the range as a large-scale dome called the Gianbul dome. This Gianbul dome is bounded by two oppositely directed shear zones, the NE-dipping Zanskar Shear Zone (ZSZ) on the northern flank and the SW-dipping Miyar Shear Zone (MSZ) on the southern limb. Current models for the emplacement of the HHC in NW India as a dome structure differ mainly in terms of the roles played by both the ZSZ and the MSZ during the tectonothermal evolution of the HHC. In both the channel flow model and wedge extrusion model, the ZSZ acts as a backstop normal fault along which the high-grade metamorphic rocks of the HHC of Zanskar are exhumed. In contrast, the recently proposed tectonic wedging model argues that the ZSZ and the MSZ correspond to one single detachment system that operates as a subhorizontal backthrust off of the MCT. Thus, the kinematic evolution of the two shear zones, the ZSZ and the MSZ, and their structural, metamorphic and chronological relations appear to be diagnostic features for discriminating the different models. In this paper, structural, metamorphic and geochronological data demonstrate that the MSZ and the ZSZ experienced two distinct kinematic evolutions. As such, the data presented in this paper rule out the hypothesis that the MSZ and the ZSZ constitute one single detachment system, as postulated by the tectonic wedging model. Structural, metamorphic and geochronological data are used to present an alternative tectonic model for the large-scale doming in the NW Indian Himalaya involving early NE-directed tectonics, weakness in the upper crust, reduced erosion at the orogenic front and rapid exhumation along both the ZSZ and the MSZ.

Zuni elders: Ethnography of American Indian aging

Problem/purpose. The specific aim of this focused ethnography was to provide insight into the experience of aging of the American Indian (AI) elder as demonstrated by one tribe, the Zuni of New Mexico. Discovering how Zuni elders construct the experience of aging and the associated behaviors allowed the researcher to deconstruct aging and then re-present it in a cogent description for this population. Such a description is lacking in the literature and will be useful in planning for culturally relevant eldercare services. ^ Methods. Ethnographic field techniques were used to sample from elders, pueblo members-at-large, activities, events and places. Over 1800 hrs were spent in the field spanning 14 months and five site visits, with the longest at almost 4 weeks. Developing codes for transcribed interviews, field notes, supplementary documents, photographs, videos, and artifacts was carried out during analysis. Categories and ultimately a cognitive map and model were developed which represented aging in Zuni Pueblo in 2000. ^ Findings. Zuni elders are aging in two worlds. Their primary world has been described as a sevenfold universe, a complicated structure with seven planes wherein the middle plane refers to themselves, a synthesis of all the other planes. The increasing influence of the white world has formed a ‘new middle’ out of which everyday aspects of aging are viewed. ^ Implications for nursing/gerontology. Nurses and others in gerontology must recognize that vast differences in worldviews are present between themselves and AI elders regarding health practices, spirituality, eating patterns, family roles, medicine, religion and countless other aspects of life. Their centuries old beliefs and practices drive these differences coupled with a collision with the white world. Making a paradigm shift using an appropriate lens with which to view these differences can only increase our understanding and efficacy in delivering culturally relevant care. ^